Recognizing Worlds Beyond Our Sun - NASA Science

Suggested Searches

When Hubble launched in 1990, there were no confirmed planets outside of our solar system. Hubble’s unique capabilities allow it to explore planetary systems around other stars. Scientists have since established the existence of more than 5,000 extrasolar planets.

Hubble’s unique contributions to the planet hunt include taking the first measurements of the atmospheric composition of extrasolar planets. Its observations have identified atmospheres that contain sodium, oxygen, carbon, hydrogen, carbon dioxide, methane, helium, and water vapor. Hubble observations demonstrate that we can detect and measure the basic organic components for life on planets orbiting other stars.

TRAPPIST-1 System Illustration

Hubble observed the first known system of seven Earth-sized planets around an ultra-cool dwarf star (TRAPPIST-1) that would allow liquid water to survive on four of the close-orbiting planets. All seven planets orbit closer to their star than Mercury is to our Sun and orbit very close to each other. Hubble observations suggest these planets have more compact atmospheres like those found on Earth, Venus, and Mars.

Hubble delivers first hints of possible water content of TRAPPIST-1 planets

This artist's concept shows what the TRAPPIST-1 planetary system may look like.
NASA/JPL-Caltech
Global Temperature Map of WASP-43b

Astronomers used infrared data from Hubble to make a detailed global map of an exoplanet (WASP-43b) showing the temperatures at different layers in its atmosphere, and the amount and distribution of its water vapor. The white-colored region on the daytime side is 2,800 degrees Fahrenheit (1,540°C). The nighttime-side temperatures drop below 1,000 degrees Fahrenheit (540°C).

NASA Hubble Maps the Temperature and Water Vapor on an Extreme Exoplanet

Temperature map of exoplanet WASP-43b.
NASA, ESA, and K. Stevenson, L. Kreidberg, and J. Bean (University of Chicago)
Fomalhaut b Dust Cloud

In 2004, Hubble began regularly observing what astronomers thought might be an extrasolar planet. They studied the suspected planet for 16 years, tracking its movements around the bright nearby star Fomalhaut. However, something strange was happening as the planet appeared to dim with each successive observation. Then, in 2020, it seemed to vanish completely. Further research revealed that the suspected planet may actually be a vast, expanding cloud of dust produced in a collision between two large bodies orbiting Fomalhaut.

Exoplanet Apparently Disappears in Latest Hubble Observations

Fomalhaut
NASA, ESA, and A. Gáspár and G. Rieke (University of Arizona)

A Menagerie

Hubble’s exoplanet observations reveal truly strange worlds; including one that absorbs nearly all the light that reaches it. The planet, WASP-12b, is as dark as fresh asphalt. Another, WASP-121b, is an extremely hot, football-shaped world. Hubble observations also confirmed that three super-puffy planets in the Kepler 51 system have extremely low densities. While these planets appear to be as big and bulky as Jupiter, they are actually one hundred times less massive, leading researchers to nickname them ‘cotton candy’ planets.

Size comparison of planets in our solar system with planets in Kepler 51 system. Three large Kepler 51 planets in the top row. Images of Earth, Neptune, Uranus, Saturn, and Jupiter for comparison in the bottom row.

This artist illustration depicts the three giant planets orbiting the Sun-like star Kepler 51 as compared to some of the planets in our solar system. These planets are all roughly the size of Jupiter but a very tiny fraction of its mass.

NASA, ESA, and L. Hustak and J. Olmsted (STScI)

The Football Shaped Planet

WASP-121b orbits so close to its host star that it is on the verge of ripping apart. Its upper atmosphere reaches a blazing 4,600 degrees Fahrenheit (2,540°C), causing magnesium and iron gas in the atmosphere to escape into space. Hubble observations of WASP-121b represent the first time astronomers detected elements more massive than hydrogen and helium escaping from a hot Jupiter-like planet. They also suggest the planet has a stratosphere, an atmospheric layer where temperature increases with higher altitudes.

Hubble Uncovers a ‘Heavy Metal’ Exoplanet Shaped Like a Football

This artist's illustration of WASP-121b.
NASA, ESA, and J. Olmsted (STScI)
A Blistering Pitch-Black Planet

Hubble captured another odd, seething-hot world called WASP-12b located some 1,400 light-years away. This planet is as black as fresh asphalt and is unlike other planets in its class. WASP-12b traps at least 94 percent of the visible starlight falling into its atmosphere, heating it to 4,600 degrees Fahrenheit (2,540°C). The planet is twice the size of any planet in our solar system and orbits so close to its host that it is tidally locked, which means the same side always faces the star. Unlike the day side, the planet’s night side is much cooler, some 2,200 degrees Fahrenheit (1,200°C), allowing water vapor and cloud formation. Hubble observations of the day/night boundary detected evidence of water vapor and possibly clouds and hazes in its atmosphere. WASP-12b is about 2 million miles (3 million km) away from its star and completes an orbit once a day.

NASA’s Hubble Captures Blistering Pitch-Black Planet

Artist illustration of WASP-12b.
NASA, ESA, and G. Bacon (STScI)
An Evaporating Planet

Hubble uncovered yet another odd and elusive planet called GJ 3470b. This Neptune-sized world is roughly 3.7 million miles from its star, about one-tenth the distance between Mercury and the Sun. The planet is so close to its host star that its atmosphere is evaporating. The escaping gas forms a giant cloud around the planet that Hubble's Space Telescope Imaging Spectrograph detected. Researchers estimate that the planet has lost as much as 35 percent of its atmosphere over its lifetime.

This isn’t the first shrinking, warm, Neptune-sized planet Hubble observed. A few years earlier, Hubble found that one of the warmest known Neptunes (GJ 436b) is also losing its atmosphere. These evaporating Neptunes may explain the existence of so-called hot super-Earths, which could form from a similar process that strips away the atmosphere of Neptune-sized planets, exposing their rocky cores.

Hubble Finds a Fast Evaporating Exoplanet

Artist illustration of GJ 3470b.
NASA, ESA, and D. Player (STScI)
Exocomets Plunging into a Young Star

Hubble also detected the gaseous spectral "fingerprints" on a star's light of small comets plunging into the star HD 172555. The gravitational influence of a suspected Jupiter-sized planet, depicted in the foreground, may have catapulted the comets into the star located some 95 light-years from Earth.

Hubble Detects ‘Exocomets’ Taking the Plunge Into a Young Star

This artist illustration of exoplanets plunging toward the star HD 172555.
NASA, ESA, A. Feild and G. Bacon (STScI)

A young planet whirling around a petulant red dwarf star is changing in unpredictable ways orbit-by-orbit. It is so close to its parent star that it experiences a consistent, torrential blast of energy, which evaporates its hydrogen atmosphere – causing it to puff off the planet.
But during one orbit observed with the Hubble Space Telescope, the planet looked like it wasn’t losing any material at all, while an orbit observed with Hubble a year and a half later showed clear signs of atmospheric loss. Credit: NASA's Goddard Space Flight Center; Lead Producer: Paul Morris, Narrator: Cassandra Morris

Hubble E-Book

Hubble Focus: Strange New Worlds

Hubble Focus is a series of e-books that dive deeper into specific topics in astronomy that have been forever changed by Hubble’s explorations. "Hubble Focus: Strange New Worlds" is the fourth book in the series, highlighting the mission’s recent discoveries about worlds outside our solar system, known as exoplanets.

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Hubble Focus - Strange New Worlds e-book cover

E-book cover for Hubble Focus: Strange New Worlds

NASA

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The TRAPPIST-1 star, an ultra-cool dwarf, has seven Earth-size planets orbiting it.

New Clues to TRAPPIST-1 Planet Compositions, Atmospheres

Astronomers using Hubble conducted the first spectroscopic survey of Earth-sized planets (d, e, f, and g) within the habitable zone around the nearby star TRAPPIST-1. This is a follow-up to Hubble observations made in May 2016 of the atmospheres of the inner TRAPPIST-1 planets b and c.

Upper left, black planet. Lower right half of image holds a bright yellow star with orange-red prominences.

NASA's Hubble Captures Blistering Pitch-Black Planet

Hubble observed a planet outside our solar system that traps at least 94 percent of the visible starlight falling into its atmosphere, making it look as black as fresh asphalt.

illustration of exoplanet WASP-79b and its parent star

No Blue Skies for Super-Hot Planet WASP-79b

Hubble teamed up with the Magellan Consortium's Magellan II Telescope in Chile to analyze the atmosphere of one of the largest observed exoplanets. The planet orbits a star hotter and brighter than our Sun and is some 780 light-years from Earth.

Bright blue-white star fills the lower left side of the image, an orangish planet sits nearby just right of the image center

Hubble Probes Extreme Weather on Ultra-Hot Jupiters

Hubble studied a unique class of ultra-hot exoplanets. They are bloated Jupiter-sized worlds orbiting so close to their parent stars that their temperatures rise above 3,000 degrees Fahrenheit, which is hot enough to vaporize most metals, including titanium.

Top two-thirds of the image holds a bright-light-yellow star at center. Around the star is the oval orbit of the planet. Points along the orbit indicate the planet's location and temperature measurements. The bottom third of the image holds four spheres, close-ups of the individual temperature maps.

Hubble Maps Temperature and Water Vapor on Extreme Exoplanet

Exoplanet WASP-43b is a world of extremes where seething winds howl at the speed of sound from a 3,000-degree-Fahrenheit day side, hot enough to melt steel, to a pitch-black night side with plunging temperatures below 1,000 degrees Fahrenheit.

Illustration of a pinkish planet against a black background. Planet is in the foreground at lower left, its yellow star is some distance away at upper left. Two other planets, one blue the other yellow, are off to the right. Stars dot the background.

'Cotton Candy' Planet Mysteries Unravel in New Hubble Observations

Hubble data provided the first clues to the chemistry of two of super-puffy planets located in the Kepler 51 system.

artist concept of gas giant planet circling a pair of red dwarf stars in the system OGLE-2007-BLG-349

Hubble Finds Planet Orbiting Pair of Stars

Using Hubble, and a trick of nature, astronomers confirmed the existence of a planet orbiting two stars in the system OGLE-2007-BLG-349, located 8,000 light-years away toward the center of our galaxy.

Hubble observations and data simulation of Fomalhaut star system

Exoplanet Apparently Disappears in Latest Hubble Observations

Rather than being a full-sized planet, the planetary object could instead be a vast, expanding cloud of dust produced in a collision between two large bodies orbiting the bright, nearby star Fomalhaut.

illustration comets plunging into a star with disc

Hubble Detects ‘Exocomets’ Taking the Plunge Into a Young Star

Comets outside our solar system were not directly seen around the star, but their presence was inferred by detecting gas that is likely the vaporized remnants of their icy nuclei.

Hubble Science Highlights

Discover the breadth and depth of Hubble's exciting discoveries!

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Hubble image left to right: Jupiter, Uranus, Saturn, Neptune

Studying the Planets and Moons

Hubble’s systematic observations chart the ever-changing environments of our solar system's planets and their moons.

animation of a binary asteroid with a shifting tail

Tracking Evolution in the Asteroid Belt

These conglomerates of rock and ice may hold clues to the early solar system.

Three views of Pluto. Three mottled circles in colors of yellow, grey, rusty-orange, and black.

Uncovering Icy Objects in the Kuiper Belt

Hubble’s discoveries helped NASA plan the New Horizon spacecraft’s flyby of Pluto and beyond.

The Mystic Mountain is seen as a chaotic pillar of colorful gas and dust, narrowing toward the top of the image. The dust and gas is mostly yellow, brown, and orange, all jutting against a hazy purple and blue background with a few pink stars.

Exploring the Birth of Stars

Seeing ultraviolet, visible, and near-infrared light helps Hubble uncover the mysteries of star formation.

Hubble image of the Crab Nebula

The Death Throes of Stars

When stars die, they throw off their outer layers, creating the clouds that birth new stars.

Thirty proplyds in a 6 by 5 grid. Each one is unique. Some look like tadpoles, others like bright points in a cloudy disk.

Finding Planetary Construction Zones

Hubble’s sensitivity uncovers the seeds of planets in enormous disks of gas and dust around stars.

Hubble view of an expanding halo of light around star v838 monocerotis

Seeing Light Echoes

Like ripples on a pond, pulses of light reverberate through cosmic clouds forming echoes of light.

Hubble Ultra Deep Field image

Tracing the Growth of Galaxies

Hubble's Deep Field observations are instrumental in tracing the growth of galaxies.

Comma shaped curved cloud of gases in bright white edged with bright-pink star forming regions, and threaded with rusty-brown tendrils of dust at center and throughout the comma shaped merger. All set against the black of deep space.

Galaxy Details and Mergers

Galaxies evolve through gravitational interaction with their neighbors, creating a menagerie of forms.

Computer simulation of a supermassive black hole at the core of a galaxy. Center is a black circle. Surrounding the black circle are arcs of red, blue, orange, and white. Further out from the circle are blotches of red, blue, orange, and white representing celestial objects.

Monster Black Holes are Everywhere

Supermassive black holes lie at the heart of nearly every galaxy.

Six Hubble images in a grid of three across and two down. Each is a gamma-ray burst in a host galaxy. The images are orange-red and white with hints of yellow.

Homing in on Cosmic Explosions

Hubble helps astronomers better understand and define some of the largest explosions in the universe.

Cepheid star in Andromeda galaxy (Hubble observations)

Discovering the Runaway Universe

Our cosmos is growing, and that expansion rate is accelerating.

A field of galaxies along with the curved arcs of gravitationally lensed galaxies.

Focusing in on Gravitational Lenses

Gravitational lenses are 'Nature's Boost', expanding our view deeper into space and farther back in time.

A cluster of galaxies fills the frame. A purple glow around the largest concentrations of galaxies indicates the distribution of dark matter.

Shining a Light on Dark Matter

The gravitational pull of dark matter guides the formation of everything we can see in the universe.

Top: Three views going back in time show slices of the cosmos. Bottom: A computer simulated, 3-D map of the distribution of dark matter.

Mapping the Cosmic Web

Filaments and sheets of matter create an interconnected web that forms the large-scale structure of the universe.