Exoplanet and Planetary Science with the Hubble Space Telescope

This is an artist's concept of a plume of water vapor thought to be ejected off the frigid, icy surface of the Jovian moon Europa.Image credit: NASA/ESA/K. Retherford/SWRIThe Hubble Space Telescope has made and continues to make breakthrough discoveries in exoplanet and planetary science thanks to its unprecedented telescope and instrument capabilities, its general-purpose observatory nature, and an extensive general observer program. 

Since its first direct detection of an exoplanet atmosphere, HST has contributed critically to the discovery and characterization of exoplanets and of their atmospheres. Comparative studies of giant exoplanets orbiting close to their stars have revealed a startling diversity in their atmospheric properties with detections of atomic sodium and potassium, water vapor, and obscuring clouds. HST is extensively used to measure the presence of water in the atmospheres of exoplanets because it cannot be done with any other facility on the ground or in space. HST has shown that water is present in nearly all exoplanet atmospheres, but it is often hard to determine how much water is there due to the presence of exotic clouds in these planetary atmospheres which effectively obscure or mute the signatures of water. HST has also made observations of the small Earth-sized worlds in the TRAPPIST-1 system ruling out the presence of thick hydrogen-dominated atmospheric envelopes, this is the first steps to determining the potential habitability of small rocky worlds and sets a legacy of information for JWST to follow.

The observatory has also made critical contributions to the study of protoplanetary disks and debris disks, shedding light on the formation and evolution for extrasolar planetary systems, helping us place our solar system into context. HST has measured warps in disks indicative of an exoplanet perturbing the material surrounding the young star, and archival data has been used to investigate and reveal years of images for young hot planets which have just formed.

In the solar system, HST has monitored the atmospheres of the ice and gas giant planets, studied their giant storms, measured their winds, monitor their vivid auroras and their interaction with the solar wind, and studied the effect of giant collisions against Jupiter.  HST has also discovered new moons and rings around the ice and gas giant planets, has characterized the atmospheres of the largest ones, studied volcanic activity in Io, and discovered evidence of an underground ocean in Ganymede, and of water plumes in Europa. HST has discovered new dwarf planets and new moons around some of them, including around Pluto, and has helped characterized the asteroid belt and Kuiper belt populations, unveiling unexpected behavior in asteroids and comets that have led to change our understanding of the solar system’s small-body population. Examples of these findings are the asteroids found to have cometary activity, and a comet (most likely the most primitive ever seen) found to have activity at an unpreceded large distance from the Sun.  HST has witnessed comets and, more remarkably, asteroids disintegrating before our eyes, and has monitored their debris. HST has even helped characterize what may be the first interstellar interloper, helping unveil its mysterious nature. 

HST has contributed critically to the synergy of NASA’s astrophysics and planetary science missions, helping support New Horizons, Rosetta, Mars Global Surveyor, Mars Pathfinder, Dawn, and Deep Impact, and in the future Europa Clipper.

STScI is the science operations center for HST. We help turn great science ideas into great science, highlight the results, distribute the data acquired for others to use, and bring the wonders of HST discoveries directly to the public and news media in ways that inspire, excite, challenge, and educate.

Extrasolar Planetary Systems Science Results


Planetary Discovery and Characterization

Since its breakthrough first direct detection of an exoplanet atmosphere, HST has contributed critically to the discovery of exoplanets and their atmospheric characterization.


Planetary Systems

HST observations of star-forming regions and protoplanetary disks have shed light on the formation and early evolution of extrasolar planetary systems, helping us place our solar system into context. HST observations have also shed light on the planetary material that surrounds stars of all ages, from the very young to the old white dwarfs, and the exoplanets that might be embedded in circumstellar planetesimal disks.

Solar System Science Results


Ice and Gas Giant Planets

HST has monitored the atmospheres of the ice and gas giant planets, studied their giant storms, measured their winds, and witnessed the creation of new vortexes. It has observed their vivid auroras and studied the planets’ interaction with the solar wind. HST has witnessed the effect of giant collisions of asteroids, comets and large meteors against Jupiter, and has supported the New Horizons Mission in its study of the gas giant. HST has also discovered new moons and rings around the ice and gas giant planets.


Moons and Ocean Worlds

HST has discovered new moons in the outer solar system, characterized the atmospheres of the largest ones, and monitored volcanic activity in Io. It has studied the ocean worlds, discovering evidence of an underground ocean in Ganymede, and of water plumes in Europa.

Dwarf Planets

HST has discovered new dwarf planets and new moons around some of them, including around Pluto. It has also monitored changes in Pluto’s surface and supported NASA’s New Horizons Mission finding potential Kuiper Belt targets.


Asteroids, Comets, KBOs, and Rings

HST has helped characterize the asteroid belt and Kuiper belt populations, unveiling unexpected behavior in asteroids and comets that have led to change our understanding of the solar system small-body population. Examples of these findings are the asteroids found to have cometary activity, and a comet (most likely the most primitive ever seen) found to have activity at an unpreceded large distance from the Sun. HST has witnessed comets and, more remarkably, asteroids disintegrating before our eyes, and has monitored their debris. HST has even helped characterize what may be the first interstellar interloper, helping unveil its mysterious nature.  The observatory has supported NASA’s planetary science missions Dawn, New Horizon, and Deep Impact, among others.


Terrestrial Planets

HST has observed dust storms and cyclones in Mars and the aftermath of “acid rain” in Venus. The observatory has supported NASA’s planetary science missions Mars Global Surveyor and Mars Pathfinder, among others.