Oldest Known Planet Identified

Oldest Known Planet Identified

NASA’s Hubble Space Telescope precisely measured the mass of the oldest known planet in our Milky Way galaxy. At an estimated age of 13 billion years, the planet is more than twice as old as Earth’s 4.5 billion years. It’s about as old as a planet can be. It formed around a young, sun-like star barely 1 billion years after our universe’s birth in the Big Bang. The ancient planet has had a remarkable history because it resides in an unlikely, rough neighborhood. It orbits a peculiar pair of burned-out stars in the crowded core of a cluster of more than 100,000 stars. The new Hubble findings close a decade of speculation and debate about the identity of this ancient world. Until Hubble’s measurement, astronomers had debated the identity of this object. Was it a planet or a brown dwarf? Hubble’s analysis shows that the object is 2.5 times the mass of Jupiter, confirming that it is a planet. Its very existence provides tantalizing evidence that the first planets formed rapidly, within a billion years of the Big Bang, leading astronomers to conclude that planets may be very abundant in our galaxy.

Illustration Credit: NASA and G. Bacon (STScI)

Last Updated: Dec. 8, 2015

Editor: NASA Administrator

Tags:  Exoplanets, Hubble Space Telescope, Universe


Sept. 22, 2016

Hubble Finds Planet Orbiting Pair of Stars

Two’s company, but three might not always be a crowd — at least in space.

Astronomers using NASA’s Hubble Space Telescope, and a trick of nature, have confirmed the existence of a planet orbiting two stars in the system OGLE-2007-BLG-349, located 8,000 light-years away towards the center of our galaxy.

The planet orbits roughly 300 million miles from the stellar duo, about the distance from the asteroid belt to our sun. It completes an orbit around both stars roughly every seven years. The two red dwarf stars are a mere 7 million miles apart, or 14 times the diameter of the moon’s orbit around Earth.

This artist’s illustration shows a gas giant planet circling a pair of red dwarf stars in the system OGLE-2007-BLG-349, located 8,000 light-years away. The Saturn-mass planet orbits roughly 300 million miles from the stellar duo. The two red dwarf stars are 7 million miles apart.

Credits: NASA, ESA, and G. Bacon (STScI)

The Hubble observations represent the first time such a three-body system has been confirmed using the gravitational microlensing technique. Gravitational microlensing occurs when the gravity of a foreground star bends and amplifies the light of a background star that momentarily aligns with it. The particular character of the light magnification can reveal clues to the nature of the foreground star and any associated planets.

The three objects were discovered in 2007 by an international collaboration of five different groups: Microlensing Observations in Astrophysics (MOA), the Optical Gravitational Lensing Experiment (OGLE), the Microlensing Follow-up Network (MicroFUN), the Probing Lensing Anomalies Network (PLANET), and the Robonet Collaboration. These ground-based observations uncovered a star and a planet, but a detailed analysis also revealed a third body that astronomers could not definitively identify.

“The ground-based observations suggested two possible scenarios for the three-body system: a Saturn-mass planet orbiting a close binary star pair or a Saturn-mass and an Earth-mass planet orbiting a single star,” explained David Bennett of the NASA Goddard Space Flight Center in Greenbelt, Maryland, the paper’s first author.

The sharpness of the Hubble images allowed the research team to separate the background source star and the lensing star from their neighbors in the very crowded star field. The Hubble observations revealed that the starlight from the foreground lens system was too faint to be a single star, but it had the brightness expected for two closely orbiting red dwarf stars, which are fainter and less massive than our sun. “So, the model with two stars and one planet is the only one consistent with the Hubble data,” Bennett said.

Bennett’s team conducted the follow-up observations with Hubble’s Wide Field Planetary Camera 2. “We were helped in the analysis by the almost perfect alignment of the foreground binary stars with the background star, which greatly magnified the light and allowed us to see the signal of the two stars,” Bennett explained.

Kepler has discovered 10 other planets orbiting tight binary stars, but these are all much closer to their stars than the one studied by Hubble.

Now that the team has shown that microlensing can successfully detect planets orbiting double-star systems, Hubble could provide an essential role in this new realm in the continued search for exoplanets.

The team’s results have been accepted for publication in The Astronomical Journal.

Felicia Chou
NASA Headquarters, Washington

Donna Weaver / Ray Villard
Space Telescope Science Institute, Baltimore
410-338-4493 / 410-338-4514
dweaver@stsci.edu / villard@stsci.edu

David Bennett
NASA’s Goddard Space Flight Center, Greenbelt, Md.

Last Updated: Sept. 22, 2016

Editor: Rob Garner

Tags:  Exoplanets, Goddard Space Flight Center, Hubble Space Telescope, Universe

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July 20, 2016

RELEASE 16-076

NASA’s Hubble Telescope Makes First Atmospheric Study of Earth-Sized Exoplanets

This artist’s illustration shows two Earth-sized planets, TRAPPIST-1b and TRAPPIST-1c, passing in front of their parent red dwarf star, which is much smaller and cooler than our sun. NASA’s Hubble Space Telescope looked for signs of atmospheres around these planets.

Credits: NASA/ESA/STScI/J. de Wit (MIT)

Using NASA’s Hubble Space Telescope, astronomers have conducted the first search for atmospheres around temperate, Earth-sized planets beyond our solar system and found indications that increase the chances of habitability on two exoplanets.

Specifically, they discovered that the exoplanets TRAPPIST-1b and TRAPPIST-1c, approximately 40 light-years away, are unlikely to have puffy, hydrogen-dominated atmospheres usually found on gaseous worlds.

“The lack of a smothering hydrogen-helium envelope increases the chances for habitability on these planets,” said team member Nikole Lewis of the Space Telescope Science Institute (STScI) in Baltimore. “If they had a significant hydrogen-helium envelope, there is no chance that either one of them could potentially support life because the dense atmosphere would act like a greenhouse.”

Julien de Wit of the Massachusetts Institute of Technology in Cambridge, Massachusetts, led a team of scientists to observe the planets in near-infrared light using Hubble’s Wide Field Camera 3. They used spectroscopy to decode the light and reveal clues to the chemical makeup of an atmosphere. While the content of the atmospheres is unknown and will have to await further observations, the low concentration of hydrogen and helium has scientists excited about the implications.

“These initial Hubble observations are a promising first step in learning more about these nearby worlds, whether they could be rocky like Earth, and whether they could sustain life,” says Geoff Yoder, acting associate administrator for NASA’s Science Mission Directorate in Washington. “This is an exciting time for NASA and exoplanet research.”

The planets orbit a red dwarf star at least 500 million years old, in the constellation of Aquarius. They were discovered in late 2015 through a series of observations by the TRAnsiting Planets and PlanetesImals Small Telescope (TRAPPIST), a Belgian robotic telescope located at ESA’s (European Space Agency’s) La Silla Observatory in Chile.

TRAPPIST-1b completes a circuit around its red dwarf star in 1.5 days and TRAPPIST-1c in 2.4 days. The planets are between 20 and 100 times closer to their star than the Earth is to the sun. Because their star is so much fainter than our sun, researchers think that at least one of the planets, TRAPPIST-1c, may be within the star’s habitable zone, where moderate temperatures could allow for liquid water to pool.

On May 4, 2016, NASA’s Hubble Space Telescope made the first spectroscopic measurements of two of the three known Earth-sized exoplanets in the TRAPPIST-1 system, just 40 light-years away.

Credits: NASA

On May 4, astronomers took advantage of a rare simultaneous transit, when both planets crossed the face of their star within minutes of each other, to measure starlight as it filtered through any existing atmosphere. This double-transit, which occurs only every two years, provided a combined signal that offered simultaneous indicators of the atmospheric characters of the planets.

The researchers hope to use Hubble to conduct follow-up observations to search for thinner atmospheres, composed of elements heavier than hydrogen, like those of Earth and Venus.

“With more data, we could perhaps detect methane or see water features in the atmospheres, which would give us estimates of the depth of the atmospheres,” said Hannah Wakeford, the paper’s second author, at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Observations from future telescopes, including NASA’s James Webb Space Telescope, will help determine the full composition of these atmospheres and hunt for potential biosignatures, such as carbon dioxide and ozone, in addition to water vapor and methane. Webb also will analyze a planet’s temperature and surface pressure – key factors in assessing its habitability.

“These Earth-sized planets are the first worlds that astronomers can study in detail with current and planned telescopes to determine whether they are suitable for life,” said de Wit. “Hubble has the facility to play the central atmospheric pre-screening role to tell astronomers which of these Earth-sized planets are prime candidates for more detailed study with the Webb telescope.”

The results of the study appear in the July 20 issue of the journal Nature.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA. Goddard manages the telescope and STScI conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington.

For imaged and more information about Hubble, visit:




Felicia Chou
Headquarters, Washington

Donna Weaver / Ray Villard
Space Telescope Science Institute, Baltimore
410-338- 4493 / 410-338-4514
dweaver@stsci.edu / villard@stsci.edu

Last Updated: July 20, 2016

Editor: Karen Northon

Tags:  Exoplanets, Goddard Space Flight Center, Hubble Space Telescope, Universe

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Solar System and Beyond

June 8, 2016

Cloudy Days on Exoplanets May Hide Atmospheric Water

Hot Jupiters, exoplanets around the same size as Jupiter that orbit very closely to their stars, often have cloud or haze layers in their atmospheres. This may prevent space telescopes from detecting atmospheric water that lies beneath the clouds, according to a study in the Astrophysical Journal.

Credits: NASA/JPL-Caltech

Full image and caption

Water is a hot topic in the study of exoplanets, including “hot Jupiters,” whose masses are similar to that of Jupiter, but which are much closer to their parent star than Jupiter is to the sun. They can reach a scorching 2,000 degrees Fahrenheit (1,100 degrees Celsius), meaning any water they host would take the form of water vapor.

Astronomers have found many hot Jupiters with water in their atmospheres, but others appear to have none. Scientists at NASA’s Jet Propulsion Laboratory, Pasadena, California, wanted to find out what the atmospheres of these giant worlds have in common.

Researchers focused on a collection of hot Jupiters studied by NASA’s Hubble Space Telescope. They found that the atmospheres of about half of the planets were blocked by clouds or haze.

“The motivation of our study was to see what these planets would be like if they were grouped together, and to see whether they share any atmospheric properties,” said Aishwarya Iyer, a JPL intern and master’s degree candidate at California State University, Northridge, who led the study.

The new study, published in the June 1 issue of the Astrophysical Journal, suggests that clouds or haze layers could be preventing a substantial amount of atmospheric water from being detected by space telescopes. The clouds themselves are likely not made of water, as the planets in this sample are too hot for water-based clouds.

“Clouds or haze seem to be on almost every planet we studied,” Iyer said. “You have to be careful to take clouds or haze into account, or else you could underestimate the amount of water in an exoplanet’s atmosphere by a factor of two.”

In the study, scientists looked at a set of 19 hot Jupiters previously observed by Hubble. The telescope’s Wide Field Camera 3 had detected water vapor in the atmospheres of 10 of these planets, and no water on the other nine. But that information was spread across more than a dozen studies. The methods of analyzing and interpretation varied because the studies were conducted separately. There had not been one overarching analysis of all these planets.

To compare the planets and look for patterns, the JPL team had to standardize the data: Researchers combined the datasets for all 19 hot Jupiters to create an average overall light spectrum for the group of planets. They then compared these data to models of clear, cloud-free atmospheres and those with various cloud thicknesses.

The scientists determined that, for almost every planet they studied, haze or clouds were blocking half of the atmosphere, on average.

“In some of these planets, you can see water peeking its head up above the clouds or haze, and there could still be more water below,” Iyer said.

Scientists do not yet know the nature of these clouds or hazes, including what they are they made of.

“Clouds or haze being on almost all these planets is pretty surprising,” said Robert Zellem, a postdoctoral fellow at JPL and co-author of the study.

The implications of this result agree with findings published in the Dec. 14, 2015, issue of the journal Nature. The Nature study used data from NASA’s Hubble and Spitzer Space Telescopes to suggest that clouds or haze could be hiding undetected water in hot Jupiters. This new study uses exoplanet data from a single instrument on Hubble to uniformly characterize a larger group of hot Jupiters, and is the first to quantify how much of the atmosphere would be shielded as a result of clouds or haze.

The new research could have implications for follow-up studies with future space observatories, such as NASA’s James Webb Space Telescope. Exoplanets with thick cloud covers blocking the detection of water and other substances may be less desirable targets for more extensive study.

These results are also important for figuring out how planets form, scientists say.

“Did these planets form in their current positions or migrate toward their host stars from farther out? Understanding the abundances of molecules such as water helps us answer those questions,” Zellem said.

“This paper is an exciting step forward for the study of exoplanets and comparing their properties,” said Mark Swain, study co-author and group supervisor for the exoplanet discovery and science group at JPL.

Michael Line of the University of California, Santa Cruz, also contributed to the study. Other co-authors from JPL included Gael Roudier, Graca Rocha and John Livingston.

For more information about the Hubble Space Telescope, visit:


Elizabeth Landau
Jet Propulsion Laboratory, Pasadena, Calif.


Last Updated: June 8, 2016

Editor: Tony Greicius

Tags:  Exoplanets, Goddard Space Flight Center, Hubble Space Telescope, Jet Propulsion Laboratory, Universe

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Solar System and Beyond

May 2, 2016

Promising Worlds Found Around Nearby Ultra-cool Dwarf Star

This artist’s impression shows an imagined view of the three planets orbiting an ultra-cool dwarf star just 40 light-years from Earth that were discovered using the TRAPPIST telescope at ESO’s La Silla Observatory. In this view, one of the inner planets is seen in transit across the disc of its tiny and dim parent star.

Credits: ESO/M. Kornmesser/N. Risinger (skysurvey.org)

Dr. Susan Lederer stands next to the UKIRT Telescope located on Mauna Kea on the island of Hawai’i, which was used to confirm the existence of the newly discovered exoplanets and constrain their orbital periods. Says Lederer, “For such a small, cool, star giving off so much of its light in the infrared, the UKIRT telescope, designed solely for infrared observations, was ideally suited for confirming the existence of these Earth-sized planets.”

Astronomers using the TRAPPIST telescope at ESO’s La Silla Observatory have discovered three planets with sizes and temperatures similar to those of Venus and Earth, orbiting an ultra-cool dwarf star just 40 light-years from Earth.

Michaël Gillon of the University of Liège in Belgium, leading a team of astronomers including Susan M. Lederer of NASA Johnson Space Center, have used the TRAPPIST telescope to observe the star 2MASS J23062928-0502285, now also known as TRAPPIST-1. They found that this dim and cool star faded slightly at regular intervals, indicating that several objects were passing between the star and the Earth. Detailed analysis showed that three planets are present around the star.

TRAPPIST-1 is an ultra-cool dwarf star — it is much cooler and redder than the Sun and barely larger than Jupiter. Despite being so close to the Earth, this star is too dim and too red to be seen with the naked eye or even visually with a large amateur telescope. It lies in the constellation of Aquarius (The Water Carrier).

Follow-up observations with larger telescopes, including the HAWK-I instrument on ESO’s 8-metre Very Large Telescope in Chile, have shown that the planets orbiting TRAPPIST-1 have sizes very similar to that of Earth. Two of the planets have orbital periods of about 1.5 days and 2.4 days respectively, and the third planet has a less well-determined orbital period in the range 4.5 to 73 days.

With such short orbital periods, the planets are between 20 and 100 times closer to their star than the Earth to the Sun. The structure of this planetary system is much more similar in scale to the system of Jupiter’s moons than to that of the Solar System,” explains Michaël Gillon.

Although they orbit very close to their host dwarf star, the inner two planets only receive four times and twice, respectively, the amount of radiation received by the Earth, because their star is much fainter than the Sun. That puts them closer to the star than the so-called habitable zone for this system, defined as having surface temperatures where liquid water can exist, although it is still possible that they possess potentially habitable regions on their surfaces. The third, outer, planet’s orbit is not yet well known, but it probably receives less radiation than the Earth does, but maybe still enough to lie within the habitable zone. The new results will be published in the journal Nature on 2 May 2016.

NASA’s Hubble Space Telescope and K2, the Kepler spacecraft’s second mission, will be observing TRAPPIST-1 and its planets later this year.

Fortuitously, two of these planets are transiting the star on May 4, an event that happens only once every two years as seen from Earth. Astronomers hope to make measurements of the atmospheres of both of these planets and look for evidence of water vapor. The Hubble Space Telescope can characterize the atmospheres of the planets in the TRAPPIST-1 system by observing them as they pass in front of, or transit, their parent star. Hubble astronomers will use spectroscopy to measure starlight as it filters through a planet’s atmosphere.

K2 will observe TRAPPIST-1 as part of their Campaign 12, which is scheduled to take place from Dec. 15 to March 4, 2017. The data are expected to be available at the public archive the end of May 2017.

K2 will observe tens of transits of the two close-in Earth-sized exoplanets during the approximately 80-day campaign. The continuous and multiple observations will allow for measurements of predicted transit timing variations – the gravitational interaction between planets that cause transits to occur slightly earlier or slightly later than predicted. This will provide estimates of the masses of these exoplanets. Using K2’s mass measurements and TRAPPIST’s ground-based size measurements, astronomers can calculate or constrain the density of the exoplanets to determine if they could be rocky worlds.

K2’s observations will also help scientists determine the orbital period of the third planet, and help find any additional small transiting objects in the system.

The TRAPPIST-1 system is an ideal target for NASA’s James Webb Space Telescope. Webb’s infrared sensitivity will be able to detect carbon dioxide, methane, water vapor, and other molecules common in the atmospheres of the rocky planets in our own solar system.

Thanks to several giant telescopes currently under construction, including ESO’s E-ELT and the NASA/ESA/CSA James Webb Space Telescope due to launch for 2018, we will soon be able to study the atmospheric composition of these planets and to explore them first for water, then for traces of biological activity. That’s a giant step in the search for life in the Universe,” says Julien de Wit, a co-author from the Massachusetts Institute of Technology (MIT) in the USA.

The TRAPPIST survey is a prototype for a more ambitious project called SPECULOOS that will be installed at ESO’s Paranal Observatory.

For more information, please go to:http://www.eso.org/public/news/eso1615/

Last Updated: Nov. 2, 2016

Editor: Mark Garcia

Tags:  Exoplanets, Hubble Space Telescope, Johnson Space Center, Kepler and K2, Stars, Universe

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Feb. 18, 2016

Hubble Directly Measures Rotation of Cloudy ‘Super-Jupiter’

Astronomers using NASA’s Hubble Space Telescope have measured the rotation rate of an extreme exoplanet by observing the varied brightness in its atmosphere. This is the first measurement of the rotation of a massive exoplanet using direct imaging.

“The result is very exciting,” said Daniel Apai of the University of Arizona in Tucson, leader of the Hubble investigation. “It gives us a unique technique to explore the atmospheres of exoplanets and to measure their rotation rates.”

The planet, called 2M1207b, is about four times more massive than Jupiter and is dubbed a “super-Jupiter.” It is a companion to a failed star known as a brown dwarf, orbiting the object at a distance of 5 billion miles. By contrast, Jupiter is approximately 500 million miles from the sun. The brown dwarf is known as 2M1207. The system resides 170 light-years away from Earth.

This is an illustration of a planet that is four times the mass of Jupiter and orbits 5 billion miles from a brown dwarf companion object (the bright red star seen in the background). The planet is only 170 light-years away. Our sun is a faint star in the background.

Credits: NASA, ESA, and G. Bacon/STScI

Hubble’s image stability, high resolution, and high-contrast imaging capabilities allowed astronomers to precisely measure the planet’s brightness changes as it spins. The researchers attribute the brightness variation to complex clouds patterns in the planet’s atmosphere. The new Hubble measurements not only verify the presence of these clouds, but also show that the cloud layers are patchy and colorless.

Astronomers first observed the massive exoplanet 10 years ago with Hubble. The observations revealed that the exoplanet’s atmosphere is hot enough to have “rain” clouds made of silicates: vaporized rock that cools down to form tiny particles with sizes similar to those in cigarette smoke. Deeper into the atmosphere, iron droplets are forming and falling like rain, eventually evaporating as they enter the lower levels of the atmosphere.

“So at higher altitudes it rains glass, and at lower altitudes it rains iron,” said Yifan Zhou of the University of Arizona, lead author on the research paper. “The atmospheric temperatures are between about 2,200 to 2,600 degrees Fahrenheit.”

The super-Jupiter is so hot that it appears brightest in infrared light. Astronomers used Hubble’s Wide Field Camera 3 to analyze the exoplanet in infrared light to explore the object’s cloud cover and measure its rotation rate. The planet is hot because it is only about 10 million years old and is still contracting and cooling. For comparison, Jupiter in our solar system is about 4.5 billion years old.

The planet, however, will not maintain these sizzling temperatures. Over the next few billion years, the object will cool and fade dramatically. As its temperature decreases, the iron and silicate clouds will also form lower and lower in the atmosphere and will eventually disappear from view.

Zhou and his team have also determined that the super-Jupiter completes one rotation approximately every 10 hours, spinning at about the same fast rate as Jupiter.

This super-Jupiter is only about five to seven times less massive than its brown-dwarf host. By contrast, our sun is about 1,000 times more massive than Jupiter. “So this is a very good clue that the 2M1207 system we studied formed differently than our own solar system,” Zhou explained. The planets orbiting our sun formed inside a circumstellar disk through accretion. But the super-Jupiter and its companion may have formed throughout the gravitational collapse of a pair of separate disks.

“Our study demonstrates that Hubble and its successor, NASA’s James Webb Space Telescope, will be able to derive cloud maps for exoplanets, based on the light we receive from them,” Apai said. Indeed, this super-Jupiter is an ideal target for the Webb telescope, an infrared space observatory scheduled to launch in 2018. Webb will help astronomers better determine the exoplanet’s atmospheric composition and derive detailed maps from brightness changes with the new technique demonstrated with the Hubble observations.

Results from this study will appear in the Feb. 11, 2016, edition of The Astrophysical Journal.

For more information about NASA’s Hubble Space Telescope, visit:


Donna Weaver / Ray Villard
Space Telescope Science Institute, Baltimore, Maryland
410-338-4493 / 410-338-4514
dweaver@stsci.edu / villard@stsci.edu

Last Updated: Feb. 18, 2016

Editor: Ashley Morrow

Tags:  Exoplanets, Goddard Space Flight Center, Hubble Space Telescope, Universe

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Dec. 14, 2015

Missing Water Mystery Solved in Comprehensive Survey of Exoplanets

A survey of 10 hot, Jupiter-sized exoplanets conducted with NASA’s Hubble and Spitzer space telescopes has led a team to solve a long-standing mystery — why some of these worlds seem to have less water than expected. The findings offer new insights into the wide range of planetary atmospheres in our galaxy and how planets are assembled.

Of the nearly 2,000 planets confirmed to be orbiting other stars, a subset are gaseous planets with characteristics similar to those of Jupiter but orbit very close to their stars, making them blistering hot.

This image shows an artist’s impression of the ten hot Jupiter exoplanets studied by astronomer David Sing and his colleagues using the Hubble and Spitzer space telescopes. From top left to lower left, these planets are WASP-12b, WASP-6b, WASP-31b, WASP-39b, HD 189733b, HAT-P-12b, WASP-17b, WASP-19b, HAT-P-1b and HD 209458b.

Credits: NASA, ESA, and D. Sing (University of Exeter)

Their close proximity to the star makes them difficult to observe in the glare of starlight. Due to this difficulty, Hubble has only explored a handful of hot Jupiters in the past. These initial studies have found several planets to hold less water than predicted by atmospheric models.

The international team of astronomers has tackled the problem by making the largest-ever spectroscopic catalogue of exoplanet atmospheres. All of the planets in the catalog follow orbits oriented so the planet passes in front of their parent star, as seen from Earth. During this so-called transit, some of the starlight travels through the planet’s outer atmosphere. “The atmosphere leaves its unique fingerprint on the starlight, which we can study when the light reaches us,” explains co-author Hannah Wakeford, now at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

By combining data from NASA’s Hubble and Spitzer Space Telescopes, the team was able to attain a broad spectrum of light covering wavelengths from the optical to infrared. The difference in planetary radius as measured between visible and infrared wavelengths was used to indicate the type of planetary atmosphere being observed for each planet in the sample, whether hazy or clear. A cloudy planet will appear larger in visible light than at infrared wavelengths, which penetrate deeper into the atmosphere.  It was this comparison that allowed the team to find a correlation between hazy or cloudy atmospheres and faint water detection.

“I’m really excited to finally see the data from this wide group of planets together, as this is the first time we’ve had sufficient wavelength coverage to compare multiple features from one planet to another,” says David Sing of the University of Exeter, U.K., lead author of the paper. “We found the planetary atmospheres to be much more diverse than we expected.”

“Our results suggest it’s simply clouds hiding the water from prying eyes, and therefore rule out dry hot Jupiters,” explained co-author Jonathan Fortney of the University of California, Santa Cruz. “The alternative theory to this is that planets form in an environment deprived of water, but this would require us to completely rethink our current theories of how planets are born.”

The results are being published in the Dec. 14 issue of the British science journal Nature.

The study of exoplanetary atmospheres is currently in its infancy. Hubble’s successor, the James Webb Space Telescope, will open a new infrared window on the study of exoplanets and their atmospheres.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

NASA’s Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA.

For images and more information about this study and Hubble, visit:

For more information about Spitzer, visit:

Whitney Clavin
NASA’s Jet Propulsion Laboratory, Pasadena, California

Rob Gutro
NASA’s Goddard Space Flight Center, Greenbelt, Maryland

Ray Villard
Space Telescope Science Institute, Baltimore, Maryland

Last Updated: Dec. 14, 2015

Editor: Ashley Morrow

Tags:  Exoplanets, Goddard Space Flight Center, Hubble Space Telescope, Spitzer Space Telescope, Universe

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Oct. 29, 2015

Spirals in Dust Around Young Stars May Betray Presence Of Massive Planets

A team of astronomers is proposing that huge spiral patterns seen around some newborn stars, merely a few million years old (about one percent our sun’s age), may be evidence for the presence of giant unseen planets. This idea not only opens the door to a new method of planet detection, but also could offer a look into the early formative years of planet birth.

Though astronomers have cataloged thousands of planets orbiting other stars, the very earliest stages of planet formation are elusive because nascent planets are born and embedded inside vast, pancake-shaped disks of dust and gas encircling newborn stars, known as circumstellar disks.

The conclusion that planets may betray their presence by modifying circumstellar disks on large scales is based on detailed computer modeling of how gas-and-dust disks evolve around newborn stars, which was conducted by two NASA Hubble Fellows, Ruobing Dong of Lawrence Berkeley National Laboratory, and Zhaohuan Zhu of Princeton University. Their research was published in the Aug. 5 edition of The Astrophysical Journal Letters.

“It’s difficult to see suspected planets inside a bright disk surrounding a young star. Based on this study, we are convinced that planets can gravitationally excite structures in the disk. So if you can identify features in a disk and convince yourself those features are created by an underlying planet that you cannot see, this would be a smoking gun of forming planets,” Dong said.

Identifying large-scale features produced by planets offers another method of planet detection that is quite different from all other techniques presently used. This approach can help astronomers find currently-forming planets, and address when, how, and where planets form.

Gaps and rings seen in other circumstellar disks suggest invisible planets embedded in the disk. However gaps, presumably swept clean by a planet’s gravity, often do not help show location of the planet. Also, because multiple planets together may open a single common gap, it’s very challenging to estimate their number and masses.

Ground-based telescopes have photographed two large-scale spiral arms around two young stars, SAO 206462 and MWC 758. A few other nearby stars also show smaller spiral-like features. “How they are created has been a big mystery until now.  Scientists had a hard time explaining these features,” Dong said. If the disks were very massive, they would have enough self-gravity to become unstable and set up wave-like patterns. But the disks around SAO 206462 and MWC 758 are probably just a few percent of the central star’s mass and therefore are not gravitationally unstable.

The team generated computer simulations of the dynamics of a disk and how the star’s radiation propagates through a disk with embedded planets. This modeling created spiral structures that very closely resemble observations. The mutual gravitational interaction between the disk and the planet creates regions where the density of gas and dust increases, like traffic backing up on a crowded expressway. The differential rotation of the disk around the star smears these over-dense regions into spiral waves. Although it had been speculated that planets can produce spiral arms, we now think we know how.

A computer model reproduces the two-spiral-arm structure; the “x” is the Location of a putative planet. The planet, which cannot be seen directly, probably excites the two spiral arms.

Credits: NASA/ESA/ESO/M. Benisty et al. Univ. of Grenoble/R. Dong, Lawrence Berkeley National Lab/Z. Zhu, Princeton Univ.

“Simulations also suggest that these spiral arms have rich information about the unseen planet, revealing not only its position but also its mass,” Zhu said. The simulations show that if there were no planet present, the disk would look smooth. To make the grand-scale spiral arms seen in the SAO 206462 and MWC 758 systems, the unseen planet would have to be bulky, at least 10 times the mass of Jupiter, the largest planet in our solar system.

Observations taken by the European Southern Observatory’s Very Large Telescope show a protoplanetary disk around the young star MWC 758. The disk has two spiral arms that extend over 10 billion miles from the star.

Credits: NASA/ESA/ESO/M. Benisty et al. Univ. of Grenoble/R. Dong, Lawrence Berkeley National Lab/Z. Zhu, Princeton Univ.

The first planet orbiting a normal star was identified in 1995. Thanks to ground-based telescopes and NASA’s Kepler mission, a few thousand exoplanets have been cataloged to date. But because the planets are in mature systems, many millions or a few billion years old, they offer little direct clues as to how they formed.

“There are many theories about how planets form but very little work based on direct observational evidence confirming these theories,” Dong said. “If you see signs of a planet in a disk right now, it tells you when, where, and how planets form.”

Astronomers will use the upcoming NASA James Webb Space Telescope to probe circumstellar disks and look for features, as simulated by the modeling, and will then try to directly observe the predicted planet causing the density waves.

For more information, visit:



Ray Villard
Space Telescope Science Institute, Baltimore, Maryland
410-338-4488 / 410-338-4514

Last Updated: Oct. 29, 2015

Editor: Ashley Morrow

Tags:  Exoplanets, Goddard Space Flight Center, Hubble Space Telescope, Stars, Universe

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Oct. 20, 2015

Most Earth-Like Worlds Have Yet to Be Born, According to Theoretical Study

Earth came early to the party in the evolving universe. According to a new theoretical study, when our solar system was born 4.6 billion years ago only eight percent of the potentially habitable planets that will ever form in the universe existed. And, the party won’t be over when the sun burns out in another 6 billion years. The bulk of those planets – 92 percent – have yet to be born.

This conclusion is based on an assessment of data collected by NASA’s Hubble Space Telescope and the prolific planet-hunting Kepler space observatory.

“Our main motivation was understanding the Earth’s place in the context of the rest of the universe,” said study author Peter Behroozi of the Space Telescope Science Institute (STScI) in Baltimore, Maryland, “Compared to all the planets that will ever form in the universe, the Earth is actually quite early.”

This is an artist’s impression of innumerable Earth-like planets that have yet to be born over the next trillion years in the evolving universe.

Credits: NASA, ESA, and G. Bacon (STScI)

Looking far away and far back in time, Hubble has given astronomers a “family album” of galaxy observations that chronicle the universe’s star formation history as galaxies grew. The data show that the universe was making stars at a fast rate 10 billion years ago, but the fraction of the universe’s hydrogen and helium gas that was involved was very low. Today, star birth is happening at a much slower rate than long ago, but there is so much leftover gas available that the universe will keep cooking up stars and planets for a very long time to come.

“There is enough remaining material [after the big bang] to produce even more planets in the future, in the Milky Way and beyond,” added co-investigator Molly Peeples of STScI.

Kepler’s planet survey indicates that Earth-sized planets in a star’s habitable zone, the perfect distance that could allow water to pool on the surface, are ubiquitous in our galaxy. Based on the survey, scientists predict that there should be 1 billion Earth-sized worlds in the Milky Way galaxy at present, a good portion of them presumed to be rocky. That estimate skyrockets when you include the other 100 billion galaxies in the observable universe.

This leaves plenty of opportunity for untold more Earth-sized planets in the habitable zone to arise in the future. The last star isn’t expected to burn out until 100 trillion years from now. That’s plenty of time for literally anything to happen on the planet landscape.

The researchers say that future Earths are more likely to appear inside giant galaxy clusters and also in dwarf galaxies, which have yet to use up all their gas for building stars and accompanying planetary systems. By contrast, our Milky Way galaxy has used up much more of the gas available for future star formation.

A big advantage to our civilization arising early in the evolution of the universe is our being able to use powerful telescopes like Hubble to trace our lineage from the big bang through the early evolution of galaxies. The observational evidence for the big bang and cosmic evolution, encoded in light and other electromagnetic radiation, will be all but erased away 1 trillion years from now due to the runaway expansion of space. Any far-future civilizations that might arise will be largely clueless as to how or if the universe began and evolved.

The results will appear in the October 20 Monthly Notices of the Royal Astronomical Society.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington.

For images and more information visit:




Donna Weaver / Ray Villard

Space Telescope Science Institute, Baltimore, Maryland

dweaver@stsci.edu / villard@stsci.edu

Last Updated: Nov. 21, 2016

Editor: Karl Hille

Tags:  Exoplanets, Goddard Space Flight Center, Hubble Space Telescope, Kepler and K2, Universe

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Oct. 7, 2015

Mysterious Ripples Found Racing Through Planet-forming Disk

Astronomers using NASA’s Hubble Space Telescope and the European Southern Observatory’s (ESO) Very Large Telescope in Chile have discovered never-before-seen features within the dusty disk surrounding the young, nearby star AU Microscopii (AU Mic).The fast-moving, wave-like structures are unlike anything ever observed, or even predicted in a circumstellar disk, said researchers of a new analysis. This new, unexplained phenomenon may provide valuable clues about how planets form inside these star-surrounding disks.

This set of images of a 40 billion-mile diameter edge-on disk encircling the young star AU Microscopii reveals a string of mysterious wave-like features. Astronomers discovered the ripples are moving across the disk at speed of 22,000 miles per hour. The cause of the phenomenon is unknown and never-before seen in stellar gas and dust disks.

Credits: NASA, ESA, ESO, A. Boccaletti (Paris Observatory)

AU Mic is located 32 light-years away in the southern constellation Microscopium. It is an optimal star to observe because its circumstellar disk is tilted edge-on to our view from Earth. This allow for certain details in the disk to be better seen. Astronomers have been searching AU Mic’s disk for any signs of clumpy or warped features that might offer evidence for planet formation. They discovered a very unusual feature near the star by using ESO’s SPHERE (Spectro-Polarimetric High-contrast Exoplanet Research) instrument, mounted on the Very Large Telescope.

“The images from SPHERE show a set of unexplained features in the disk, which have an arc-like, or wave-like structure unlike anything that has ever been observed before,” said Anthony Boccaletti of the Paris Observatory, the paper’s lead author.

The images reveal a train of wave-like arches, resembling ripples in water. After spotting the features in the SPHERE data the team turned to earlier Hubble images of the disk, taken in 2010 and 2011. These features were not recognized in the initial Hubble observations. But once astronomers reprocessed the Hubble images they not only identified the features but realized that they had changed over time. The researchers report that these ripples are moving — and they are moving very fast.

“We ended up with enough information to track the movement of these strange features over a four-year period,” explained team member Christian Thalmann of the Swiss Federal Institute of Technology in Zurich, Switzerland. “By doing this, we found that the arches are racing away from the star at speeds of up to 10 kilometers per second (22,000 miles per hour)! Co-investigator Carol Grady of Eureka Scientific in Oakland, California, added, “Because nothing like this has been observed or predicted in theory we can only hypothesize when it comes to what we are seeing and how it came about.”

The ripples farther away from the star seem to be moving faster than those closer to it. At least three of the features are moving so fast that they are escaping from the gravitational attraction of the star. Such high speeds rule out the possibility that these features are caused by objects, like planets, gravitationally disturbing material in the disk. The team has also ruled out a series of phenomena as explanations, including the collision of two massive and rare asteroid-like objects releasing large quantities of dust and spiral waves triggered by instabilities in the system’s gravity.

“One explanation for the strange structure links them to the star’s flares. AU Mic is a star with high flaring activity — it often lets off huge and sudden bursts of energy from on or near its surface,” said co-author Glenn Schneider of Steward Observatory in Phoenix, Arizona. “One of these flares could perhaps have triggered something on one of the planets — if there are planets — like a violent stripping of material, which could now be propagating through the disk, propelled by the flare’s force.”

The team plans to continue to observe the AU Mic system to try to understand what is happening. But, for now, these curious features remain an unsolved mystery.

The results will be published Oct. 8 in the British science journal Nature.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington, D.C.

For illustrations and more information about AU Mic and the Hubble Space Telescope, visit: http://www.nasa.gov/hubble or http://hubblesite.org/news/2015/36

Ray Villard
Space Telescope Science Institute, Baltimore, Maryland

Last Updated: Oct. 7, 2015

Editor: Lynn Jenner

Tags:  Exoplanets, Goddard Space Flight Center, Hubble Space Telescope, Stars, Universe

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July 30, 2015

Telescopes Team Up to Find Distant Uranus-Sized Planet Through Microlensing

NASA’s Hubble Space Telescope and the W.M. Keck Observatory in Hawaii have made independent confirmations of an exoplanet orbiting far from its central star. The planet was discovered through a technique called gravitational microlensing.

This diagram shows how astronomers observed a distant gas giant planet around OGLE-2005-BLG-169 using microlensing.

Credits: Hubble/STScI

This finding opens a new piece of discovery space in the extrasolar planet hunt: to uncover planets as far from their central stars as Jupiter and Saturn are from our sun. The Hubble and Keck Observatory results will appear in two papers in the July 30 edition of The Astrophysical Journal.

The large majority of exoplanets cataloged so far are very close to their host stars because several current planet-hunting techniques favor finding planets in short-period orbits. But this is not the case with the microlensing technique, which can find more distant and colder planets in long-period orbits that other methods cannot detect.

Microlensing occurs when a foreground star amplifies the light of a background star that momentarily aligns with it.  If the foreground star has planets, then the planets may also amplify the light of the background star, but for a much shorter period of time than their host star.   The exact timing and amount of light amplification can reveal clues to the nature of the foreground star and its accompanying planets.

The system, cataloged as OGLE-2005-BLG-169, was discovered in 2005 by the Optical Gravitational Lensing Experiment (OGLE), the Microlensing Follow-Up Network (MicroFUN), and members of the Microlensing Observations in Astrophysics (MOA) collaborations—groups that search for extrasolar planets through gravitational microlensing.

Without conclusively identifying and characterizing the foreground star, however, astronomers have had a difficult time determining the properties of the accompanying planet. Using Hubble and the Keck Observatory, two teams of astronomers have now found that the system consists of a Uranus-sized planet orbiting about 370 million miles from its parent star, slightly less than the distance between Jupiter and the Sun. The host star, however, is about 70 percent as massive as our Sun.

“These chance alignments are rare, occurring only about once every 1 million years for a given planet, so it was thought that a very long wait would be required before the planetary microlensing signal could be confirmed,” said David Bennett, the lead of the team that analyzed the Hubble data. “Fortunately, the planetary signal predicts how fast the apparent positions of the background star and planetary host star will separate, and our observations have confirmed this prediction. The Hubble and Keck Observatory data, therefore, provide the first confirmation of a planetary microlensing signal.”

In fact, microlensing is such a powerful tool that it can uncover planets whose host stars cannot be seen by most telescopes. “It is remarkable that we can detect planets orbiting unseen stars, but we’d really like to know something about the stars that these planets orbit,” explained Virginie Batista, leader of the Keck Observatory analysis. “The Keck and Hubble telescopes allow us to detect these faint planetary host stars and determine their properties.”

This simulation shows the 22-year journey of a star moving through space and passing directly in front of a more distant background star. All stars drift through space. Occasionally, a star lines up perfectly in front of a more distant star. The momentary alignment magnifies and brightens the light from the background star, an effect called gravitational microlensing.

Credits: NASA, ESA, D. Bennett (University of Notre Dame), Wiggle Puppy Productions, and G. Bacon (STScI)

Full caption and downloadable versions at STScI’s website

Planets are small and faint compared to their host stars; only a few have been observed directly outside our solar system. Astronomers often rely on two indirect techniques to hunt for extrasolar planets. The first method detects planets by the subtle gravitational tug they give to their host stars. In another method, astronomers watch for small dips in the amount of light from a star as a planet passes in front of it.

Both of these techniques work best when the planets are either extremely massive or when they orbit very close to their parent stars. In these cases, astronomers can reliably determine their short orbital periods, ranging from hours to days to a couple years.

But to fully understand the architecture of distant planetary systems, astronomers must map the entire distribution of planets around a star. Astronomers, therefore, need to look farther away from the star—from about the distance of Jupiter is from our sun, and beyond.

“It’s important to understand how these systems compare with our solar system,” said team member Jay Anderson of the Space Telescope Science Institute in Baltimore, MD. “So we need a complete census of planets in these systems. Gravitational microlensing is critical in helping astronomers gain insights into planetary formation theories.”

The planet in the OGLE system is probably an example of a “failed-Jupiter” planet, an object that begins to form a Jupiter-like core of rock and ice weighing around 10 Earth masses, but it doesn’t grow fast enough to accrete a significant mass of hydrogen and helium. So it ends up with a mass more than 20 times smaller than that of Jupiter. “Failed-Jupiter planets, like OGLE-2005-BLG-169Lb, are predicted to be more common than Jupiters, especially around stars less massive than the sun, according to the preferred theory of planet formation. So this type of planet is thought to be quite common,” Bennett said.

Microlensing takes advantage of the random motion of stars, which are generally too small to be noticed without precise measurements. If one star, however, passes nearly precisely in front of a farther background star, the gravity of the foreground star acts like a giant lens, magnifying the light from the background star.

A planetary companion around the foreground star can produce a variation in the brightening of the background star. This brightening fluctuation can reveal the planet, which can be too faint, in some cases, to be seen by telescopes. The duration of an entire microlensing event is several months, while the variation in brightening due to a planet lasts a few hours to a couple of days.

The initial microlensing data of OGLE-2005-BLG-169 had indicated a combined system of foreground and background stars plus a planet. But due to the blurring effects of our atmosphere, a number of unrelated stars are also blended with the foreground and background stars in the very crowded star field in the direction of our galaxy’s center.

The sharp Hubble and Keck Observatory images allowed the research teams to separate out the background source star from its neighbors in the very crowded star field in the direction of our galaxy’s center. Although the Hubble images were taken 6.5 years after the lensing event, the source and lens star were still so close together on the sky that their images merged into what looked like an elongated stellar image.

Astronomers can measure the brightness of both the source and planetary host stars from the elongated image. When combined with the information from the microlensing light curve, the lens brightness reveals the masses and orbital separation of the planet and its host star, as well as the distance of the planetary system from Earth. The foreground and background stars were observed in several different colors with Hubble’s Wide Field Camera 3 (WFC3), allowing independent confirmations of the mass and distance determinations.

The observations, taken with the Near Infrared Camera 2 (NIRC2) on the Keck 2 telescope more than eight years after the microlensing event, provided a precise measurement of the foreground and background stars’ relative motion. “It is the first time we were able to completely resolve the source star and the lensing star after a microlensing event. This enabled us to discriminate between two models that fit the data of the microlensing light curve,” Batista said.

The Hubble and Keck Observatory data are providing proof of concept for the primary method of exoplanet detection that will be used by NASA’s planned, space-based Wide-Field Infrared Survey Telescope (WFIRST), which will allow astronomers to determine the masses of planets found with microlensing. WFIRST will have Hubble’s sharpness to search for exoplanets using the microlensing technique. The telescope will be able to observe foreground, planetary host stars approaching the background source stars prior to the microlensing events, and receding from the background source stars after the microlensing events.

“WFIRST will make measurements like we have made for OGLE-2005-BLG-169 for virtually all the planetary microlensing events it observes. We’ll know the masses and distances for the thousands of planets discovered by WFIRST,” Bennett explained.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington.

For images and more about this study and the Hubble Space Telescope, visit:



Space Telescope Science Institute

Last Updated: July 30, 2015

Editor: Karl Hille

Tags:  Exoplanets, Goddard Space Flight Center, Hubble Space Telescope, Universe

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July 23, 2015

NASA Releases Hubble Memorable Moments Video: Brute Force

In this second video of NASA’s Hubble Memorable Moments series celebrating Hubble’s 25 years, the team scrambles to work out an unusual solution to a problem encountered during an instrument repair.

Credits: NASA

In celebration of the 25 years since the Hubble Space Telescope’s April 1990 launch, NASA is releasing the second in a series of videos showcasing moments in Hubble’s history that were memorable for Goddard’s engineers and flight operators.

“Hubble Memorable Moments:  Brute Force,” which was produced by NASA’s Goddard Space Flight Center in Greenbelt, Maryland, describes repairing the Space Telescope Imaging Spectrograph on Hubble Servicing Mission 4 in May, 2009.

Hubble team members at the Goddard Space Flight Center pose with Astronaut Mike Massimino and the handrail mock-up used during the Space Telescope Imaging Spectrograph repair on Hubble Servicing Mission 4. From left to right: Bill Nilsson, Ken Dickinson, Jeff Roddin, Mike Massimino, Bill Mitchell, James Cooper

Credits: NASA

The Space Telescope Imaging Spectrograph, or STIS, was installed on Hubble during Servicing Mission 2 in 1997. A versatile instrument taking measurements in the ultraviolet, visible, and near-infrared wavelengths, STIS has discovered supermassive black holes at the centers of galaxies, and made one of the first spectroscopic measurements of the atmosphere of an exoplanet – a planet orbiting another star.

STIS was originally designed to operate for five years, but it lasted 7.5 until a power supply failed in August, 2004. At the time, STIS was being used for about 30 percent of the Hubble observing program. Because STIS was such an incredibly useful instrument, it became a high-priority task for repair on Hubble’s final servicing mission.

Most Hubble servicing mission tasks involve replacing an instrument by swapping out large boxes, not repairing an instrument, which involves much more detailed and nimble work.  Gaining access to STIS’ electronics cards would involve removing 107 small screws, so Goddard engineers custom-designed a fastener capture plate for the task while the astronauts trained tirelessly at the Johnson Space Center for the months leading up to the mission.

The Hubble team was well prepared for this incredibly complex task.  Sometimes, however, it’s the simplest items that present a huge obstacle, and the highly trained team must scramble to quickly devise an unusual solution.

Watch the video to see how this spacewalk on May 17, 2009 played out.

“Hubble Memorable Moments: Brute Force” can be downloaded at:


For more information about the Hubble Space Telescope and its 25th anniversary festivities, visit:

http://www.nasa.gov/hubble or http://hubble25th.org

Katrina Jackson
NASA’s Goddard Space Flight Center

Last Updated: July 30, 2015

Editor: Lynn Jenner

Tags:  Exoplanets, Galaxies, Goddard Space Flight Center, Hubble Space Telescope, Science Instruments, Technology, Universe

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June 24, 2015

NASA’s Hubble Sees a “Behemoth” Bleeding Atmosphere Around a Warm Exoplanet

This artist’s concept shows “The Behemoth,” an enormous comet-like cloud of hydrogen bleeding off of a warm, Neptune-sized planet just 30 light-years from Earth. Also depicted is the parent star (a faint red dwarf) of expolanet GJ 436. The hydrogen is evaporating from the planet due to extreme radiation from the star. A phenomenon this large has never before been seen around any exoplanet.

Credits: NASA, ESA, and G. Bacon (STScI)

Astronomers using NASA’s Hubble Space Telescope have discovered an immense cloud of hydrogen dubbed “The Behemoth” bleeding from a planet orbiting a nearby star. The enormous, comet-like feature is about 50 times the size of the parent star. The hydrogen is evaporating from a warm, Neptune-sized planet, due to extreme radiation from the star.

This phenomenon has never been seen around an exoplanet so small. It may offer clues to how other planets with hydrogen-enveloped atmospheres could have their outer layers evaporated by their parent star, leaving behind solid, rocky cores. Hot, rocky planets such as these that roughly the size of Earth are known as Hot-Super Earths.

“This cloud is very spectacular, though the evaporation rate does not threaten the planet right now,” explains the study’s leader, David Ehrenreich of the Observatory of the University of Geneva in Switzerland. “But we know that in the past, the star, which is a faint red dwarf, was more active. This means that the planet evaporated faster during its first billion years of existence because of the strong radiation from the young star. Overall, we estimate that it may have lost up to 10 percent of its atmosphere over the past several billion years.”

The planet, named GJ 436b, is considered to be a “Warm Neptune,” because of its size and because it is much closer to its star than Neptune is to our sun. Although it is in no danger of having its atmosphere completely evaporated and stripped down to a rocky core, this planet could explain the existence of so-called Hot Super-Earths that are very close to their stars.

These hot, rocky worlds were discovered by the Convection Rotation and Planetary Transits (CoRoT) and NASA’s Kepler space telescope. Hot Super-Earths could be the remnants of more massive planets that completely lost their thick, gaseous atmospheres to the same type of evaporation.

Because the Earth’s atmosphere blocks most ultraviolet light, astronomers needed a space telescope with Hubble’s ultraviolet capability and exquisite precision to find “The Behemoth.”

“You would have to have Hubble’s eyes,” says Ehrenreich. “You would not see it in visible wavelengths. But when you turn the ultraviolet eye of Hubble onto the system, it’s really kind of a transformation, because the planet turns into a monstrous thing.”

Because the planet’s orbit is tilted nearly edge-on to our view from Earth, the planet can be seen passing in front of its star. Astronomers also saw the star eclipsed by ”The Behemoth” hydrogen cloud around the planet.

Ehrenreich and his team think that such a huge cloud of gas can exist around this planet because the cloud is not rapidly heated and swept away by the radiation pressure from the relatively cool red dwarf star. This allows the cloud to stick around for a longer time. The team’s findings will be published in the June 25 edition of the journal Nature.

Evaporation such as this may have happened in the earlier stages of our own solar system, when the Earth had a hydrogen-rich atmosphere that dissipated over 100 to 500 million years. If so, the Earth may previously have sported a comet-like tail.

GJ 436b resides very close to its star – less than 2 million miles — and whips around it in just 2.6 Earth days. In comparison, the Earth is 93 million miles from our sun and orbits it every 365.24 days. This exoplanet is at least 6 billion years old, and may even be twice that age. It has a mass of around 23 Earths. At just 30 light-years from Earth, it’s one of the closest known extrasolar planets.

Finding “The Behemoth” could be a game-changer for characterizing atmospheres of the whole population of Neptune-sized planets and Super-Earths in ultraviolet observations. In the coming years, Ehrenreich expects that astronomers will find thousands of this kind of planet.

The ultraviolet technique used in this study also may also spot the signature of oceans evaporating on smaller, more Earth-like planets. It will be extremely challenging for astronomers to directly see water vapor on those worlds, because it’s too low in the atmosphere and shielded from telescopes. However, when water molecules are broken by the stellar radiation into hydrogen and oxygen, the relatively light hydrogen atoms can escape the planet. If scientists spot this hydrogen evaporating from a planet that is slightly more temperate and less massive than GJ 436b, it could be an indication of an ocean on the surface.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington.

For images and more information about Hubble, visit:



Felicia Chou

Headquarters, Washington



Ann Jenkins / Ray Villard

Space Telescope Science Institute, Baltimore, Maryland

410-338-4488 / 410-338-4514

jenkins@stsci.edu / villard@stsci.edu

Last Updated: July 30, 2015

Editor: Karl Hille

Tags:  Exoplanets, Goddard Space Flight Center, Hubble Space Telescope, Universe

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June 11, 2015

RELEASE 15-121

NASA’s Hubble Telescope Detects ‘Sunscreen’ Layer on Distant Planet

Using NASA’s Hubble Telescope, scientists detected a stratosphere on the planet WASP-33b. A stratosphere occurs when molecules in the atmosphere absorb ultraviolet and visible light from the star. This absorption warms the stratosphere and acts as a kind of sunscreen layer for the planet below. This video is public domain and can be downloaded at: http://svs.gsfc.nasa.gov/goto?11898

Credits: NASA Goddard

NASA’s Hubble Space Telescope has detected a stratosphere, one of the primary layers of Earth’s atmosphere, on a massive and blazing-hot exoplanet known as WASP-33b.

The presence of a stratosphere can provide clues about the composition of a planet and how it formed. This atmospheric layer includes molecules that absorb ultraviolet and visible light, acting as a kind of “sunscreen” for the planet it surrounds. Until now, scientists were uncertain whether these molecules would be found in the atmospheres of large, extremely hot planets in other star systems.

These findings will appear in the June 12 issue of the Astrophysical Journal.

“Some of these planets are so hot in their upper atmospheres, they’re essentially boiling off into space,” said Avi Mandell, a planetary scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and a co-author of the study. “At these temperatures, we don’t necessarily expect to find an atmosphere that has molecules that can lead to these multilayered structures.”

WASP-33b’s stratosphere was detected by measuring the drop in light as the planet passed behind its star (top). Temperatures in the low stratosphere rise because of molecules absorbing radiation from the star (right). Without a stratosphere, temperatures would cool down at higher altitudes (left).

Credits: NASA/Goddard

In Earth’s atmosphere, the stratosphere sits above the troposphere — the turbulent, active-weather region that reaches from the ground to the altitude where nearly all clouds top out. In the troposphere, the temperature is warmer at the bottom – ground level – and cools down at higher altitudes.

The stratosphere is just the opposite. In this layer, the temperature increases with altitude, a phenomenon called temperature inversion. On Earth, temperature inversion occurs because ozone in the stratosphere absorbs much of the sun’s ultraviolet radiation, preventing it from reaching the surface, protecting the biosphere, and therefore warming the stratosphere instead.

Similar temperature inversions occur in the stratospheres of other planets in our solar system, such as Jupiter and Saturn. In these cases, the culprit is a different group of molecules called hydrocarbons. Neither ozone nor hydrocarbons, however, could survive at the high temperatures of most known exoplanets, which are planets outside our solar system. This leads to a debate as to whether stratospheres would exist on them at all.

Using Hubble, the researchers have settled this debate by identifying a temperature inversion in the atmosphere of WASP-33b, which has about four-and-a-half times the mass of Jupiter. Team members also think they know which molecule in WASP-33b’s atmosphere caused the inversion — titanium oxide.

“These two lines of evidence together make a very convincing case that we have detected a stratosphere on an exoplanet,” said Korey Haynes, lead author of the study. Haynes was a graduate student at George Mason University in Fairfax, Virginia, and was working at Goddard with Mandell when the research was conducted.

The researchers analyzed observations made with Hubble’s Wide Field Camera 3 by co-author Drake Deming at the University of Maryland in College Park. Wide Field Camera 3 can capture a spectrum of the near-infrared region where the signature for water appears. Scientists can use the spectrum to identify water and other gases in a distant planet’s atmosphere and determine its temperature.

Haynes and her colleagues used the Hubble observations, and data from previous studies, to measure emission from water and compare it to emission from gas deeper in the atmosphere. The team determined that emission from water was produced in the stratosphere at about 6,000 degrees Fahrenheit. The rest of the emission came from gas lower in the atmosphere that was at a temperature about 3,000 degrees Fahrenheit.

The team also presented the first observational evidence that WASP-33b’s atmosphere contains titanium oxide, one of only a few compounds that is a strong absorber of visible and ultraviolet radiation and capable of remaining in gaseous form in an atmosphere as hot as this one.

“Understanding the links between stratospheres and chemical compositions is critical to studying atmospheric processes in exoplanets,” said co-author Nikku Madhusudhan of the University of Cambridge, United Kingdom. “Our finding marks a key breakthrough in this direction.”

For images and more information about Hubble, visit:



Felicia Chou
Headquarters, Washington

Nancy Neal-Jones / Elizabeth Zubritsky
Goddard Space Flight Center, Greenbelt, Md.
301-286-0039 / 301-614-5438
nancy.n.jones@nasa.gov / elizabeth.a.zubritsky@nasa.gov

Last Updated: July 30, 2015

Editor: Karen Northon

Tags:  Exoplanets, Goddard Space Flight Center, Hubble Space Telescope, Universe

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June 5, 2015

Hubble in ‘Oh Planet, What Art Thou?’ 25th Anniversary Video

“Oh Planet, What Art Thou?” is the sixth video in a series celebrating Hubble’s 25th anniversary this year.

The video explains how Hubble has helped scientists study exoplanets, or planets outside our solar system, as never before.

This episode of “Hubble at 25” uncovers Hubble’s key role in the study of planets beyond our own solar system. Thousands of “exoplanet” candidates have been discovered. While Hubble is not responsible for most exoplanet detections, it is able to examine the chemical compositions of their atmospheres. Since these planets are too far away to ever visit in the foreseeable future, analyzing their atmospheres provides critical clues about the existence of life elsewhere in the universe.

Credits: STScI

Download this video from hubblesite.org

When Hubble was launched in 1990, the only planets we knew about were those orbiting our own sun. Since then, astronomers using both space-based telescopes such as NASA’s Kepler observatory and ground-based telescopes, have discovered a rapidly-growing number of so-called exoplanets around other stars.

“One main way we have found planets is by the transit technique,” said Sara Seager, Professor of Planetary Science and Professor of Physics at the Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts. “That is when a planet goes in front of its parent star as seen from the telescope. The observed starlight drops by a tiny amount, by 1 percent or even less.  And by measuring a star’s brightness. Minute-by-minute or hour–by-hour or day by day, we are able to spot a planet transit.”

With Hubble, scientists can go beyond measuring basic properties of transiting planets, like their mass and their size, to actually studying their atmospheric composition. They do that using spectroscopy. The light from a star with a transiting planet is spread out by Hubble’s spectrographs into its constituent colors, or wavelengths. Some of this starlight will have passed through the outer atmosphere of the exoplanet. Scientists look for places in the color spectrum where light is missing, absorbed by gases in the atmosphere. Each gas has its own distinct set of lines it removes from the starlight spectrum, so particular gases in the planet’s atmosphere can be identified. With this technique, astronomers have identified sodium, nitrogen, hydrogen, and even water vapor in various exoplanetary systems.

The Wide Field Camera 3 (WFC3) is being used to study abundance of water vapor in the atmosphere of exoplanets. WFC3 is also used to study how temperatures change in the profile (different heights) of an exoplanet’s atmosphere.

Studying the chemical makeup of an exoplanet may help find answers to the question of where life could exist elsewhere in the cosmos.

“I’d say my dream is to start my career as an astronomer and end it as a biologist,” said Dave Charbonneau, Professor of Astronomy at Harvard University. “So what I would really like to do is get at the question of life in the universe.”

The “Hubble 25th Anniversary” video series is produced by the Space Telescope Science Institute (STScI), Baltimore, which manages Hubble on behalf of NASA.

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Rob Gutro
NASA’s Goddard Space Flight Center, Greenbelt, Md.

Last Updated: July 30, 2015

Editor: Rob Garner

Tags:  Exoplanets, Goddard Space Flight Center, Hubble Space Telescope, Universe

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Sept. 24, 2014

A Sunny Outlook for ‘Weather’ on Exoplanets

Scientists were excited to discover clear skies on a relatively small planet, about the size of Neptune, using the combined power of NASA’s Hubble, Spitzer and Kepler space telescopes. The view from this planet — were it possible to fly a spaceship into its gaseous layers — is illustrated at right. Before now, all of the planets observed in this size range had been found to have high cloud layers that blocked the ability to detect molecules in the planet’s atmosphere (illustrated at left).

The clear planet, called HAT-P-11b, is gaseous with a rocky core, much like our own Neptune. Its atmosphere may have clouds deeper down, but the new observations show that the upper region is cloud-free. This good visibility enabled scientists to detect water vapor molecules in the planet’s atmosphere.

Image credit: NASA/JPL-Caltech

Last Updated: Nov. 21, 2016

Editor: Tony Greicius

Tags:  Exoplanets, Hubble Space Telescope, Kepler and K2, Spitzer Space Telescope, Universe

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July 11, 2013

NASA Hubble Finds a True Blue Planet

This artist’s concept shows exoplanet HD 189733b orbiting its yellow-orange star, HD 189733. NASA’s Hubble Space Telescope measured the actual visible-light color of the planet, which is deep blue.

Credits: NASA, ESA, and G. Bacon (STScI)

Astronomers making visible-light observations with NASA’s Hubble Space Telescope have deduced the actual color of a planet orbiting another star 63 light-years away.

The planet is HD 189733b, one of the closest exoplanets that can be seen crossing the face of its star.

Hubble’s Space Telescope Imaging Spectrograph measured changes in the color of light from the planet before, during and after a pass behind its star. There was a small drop in light and a slight change in the color of the light. “We saw the light becoming less bright in the blue but not in the green or red. Light was missing in the blue but not in the red when it was hidden,” said research team member Frederic Pont of the University of Exeter in South West England. “This means that the object that disappeared was blue.”

Earlier observations have reported evidence for scattering of blue light on the planet. The latest Hubble observation confirms the evidence.

If seen directly, this planet would look like a deep blue dot, reminiscent of Earth’s color as seen from space. That is where the comparison ends.

On this turbulent alien world, the daytime temperature is nearly 2,000 degrees Fahrenheit, and it possibly rains glass — sideways — in howling, 4,500-mph winds. The cobalt blue color comes not from the reflection of a tropical ocean as it does on Earth, but rather a hazy, blow-torched atmosphere containing high clouds laced with silicate particles. Silicates condensing in the heat could form very small drops of glass that scatter blue light more than red light.

Hubble and other observatories have made intensive studies of HD 189733b and found its atmosphere to be changeable and exotic.

HD 189733b is among a bizarre class of planets called hot Jupiters, which orbit precariously close to their parent stars. The observations yield new insights into the chemical composition and cloud structure of the entire class.

This plot compares the colors of planets in our solar system to exoplanet HD 189733b. The exoplanet’s deep blue color is produced by silicate droplets, which scatter blue light in its atmosphere.

Credits: NASA, ESA, and A. Feild (STScI)

Clouds often play key roles in planetary atmospheres. Detecting the presence and importance of clouds in hot Jupiters is crucial to astronomers’ understanding of the physics and climatology of other planets.

HD 189733b was discovered in 2005. It is only 2.9 million miles from its parent star, so close that it is gravitationally locked. One side always faces the star and the other side is always dark.

In 2007, NASA’s Spitzer Space Telescope measured the infrared light, or heat, from the planet, leading to one of the first temperature maps for an exoplanet. The map shows day side and night side temperatures on HD 189733b differ by about 500 degrees Fahrenheit. This should cause fierce winds to roar from the day side to the night side.

Text issued as NASA Headquarters release No. 13-202

Last Updated: Oct. 31, 2016

Editor: Rob Garner

Tags:  Exoplanets, Goddard Space Flight Center, Hubble Space Telescope, Universe

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April 2, 2009

Hubble Finds Hidden Exoplanet in Archival Data

In 19 years of observations, the Hubble Space Telescope has amassed a huge archive of data-an archive that may contain the telltale glow of undiscovered extrasolar planets. Such is the case with HR 8799b, shown in this artist’s concept. The planet is one of three extrasolar planets orbiting the young star HR 8799, which lies 130 light-years away. The planetary trio was originally discovered in images taken with the Keck and Gemini North telescopes in 2007 and 2008. But using a new image processing technique that suppresses the glare of the parent star, scientists found the telltale glow of the outermost planet in the system while studying Hubble archival data taken in 1998. The giant planet is young and hot, but still only 1/100,000th the brightness of its parent star. By comparison, Jupiter is one-billionth the brightness of our sun.

Image Credit: NASA, ESA, and G. Bacon (STScI)
Last Updated: Oct. 20, 2015

Editor: NASA Administrator

Tags:  Exoplanets, Hubble Space Telescope, Universe

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March 23, 2008

Evaporating Planet

Planet HD 209458b is evaporating. It is so close to its parent star that its heated atmosphere is simply expanding away into space. Some astronomers studying this distant planetary system now believe they have detected water vapor among the gases being liberated.

This controversial claim, if true, would mark the first instance of planetary water beyond our solar system, and indicate anew that life might be sustainable elsewhere in the universe. Although spectroscopic observations from the Hubble Space Telescope are the basis for the water detection claim, the planetary system is too small and faint to image. The image is an artist’s concept of the HD 209458b system.

Image Credit: NASA, European Space Agency, Alfred Vidal-Madjar (Institut d’Astrophysique de Paris, CNRS)
Last Updated: Nov. 12, 2015

Editor: NASA Administrator

Tags:  Exoplanets, Hubble Space Telescope, Universe

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March 23, 2008

Orbiting a Red Dwarf Star

This artist’s concept of a gas giant planet orbiting a red dwarf K star shows a planet has not been directly imaged, but its presence was detected in 2003 microlensing observations of a field star in our galaxy. Gravitational microlensing happens when a foreground star amplifies the light of a background star that momentarily aligns with it. Follow-up observations by Hubble Space Telescope in 2005 separated the light of the slightly offset foreground star from the background star. This allowed the host star to be identified as a red dwarf star located 19,000 light-years away. The Hubble observations allow for the planet’s mass to be estimated at 2.6 Jupiter masses. The characteristics of the lensing event show that the planet is in a Jupiter-sized orbit around its parent red star. The rings and moon around the gas giant are hypothetical, but plausible, given the nature of the family of gas giant planets in our solar system.

Image credit: NASA,ESA and G. Bacon (STScI)
Last Updated: July 13, 2016

Editor: NASA Administrator

Tags:  Exoplanets, GALEX (Galaxy Evolution Explorer), Hubble Space Telescope, Stars, Universe

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National Aeronautics and Space AdministrationPage Last Updated: Dec. 8, 2015NASA Official: Brian Dunbar

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