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Webb Science Theme

Other Worlds

Webb has the capability to look at light from tiny and distant planets, orbiting other stars, and tell us what their atmospheres are made of, as well as what their climate and weather are like. Webb can also examine objects within our own solar system, giving us new insight into the physical and chemical properties of the smallest bodies to our gas giants. From gas giants to rocky planets, from lava worlds to those with skies of silica “snow,” from interstellar comets visiting the solar system to the motion of aurora on Uranus, Webb is producing a rich variety of data on planetary systems and helping scientists investigate the potential for life beyond Earth.

Key Findings / Discoveries

Introduction: Other Worlds

In Depth: What is Webb Studying ?

Latest Research

Related Webb Science

A wide look at Saturn and several of its moons on the black background of space. Image is labeled Saturn, Webb Infrared Light, November 29, 2024. Saturn has horizontal bands, with bands at the north and south poles appearing darker orange and lightening to tan as they approach the equator. The north and south poles glow a greenish-grey. The rings appear in an icy neon white. White dots, representing several of Saturn’s moons, are labeled Titan, Janus, Dione, and Enceladus. Titan is the largest dot, and appears at the far left of the image, some distance away from Saturn and the other moons.

A wider view of Saturn from NASA’s James Webb Space Telescope shows six of Saturn’s larger moons, including the largest, Titan, at far left.

Image: NASA, ESA, CSA, STScI; Image Processing: Joseph DePasquale (STScI)

Key Questions

Building on the established science from previous missions, scientists from around the world are using the Webb Telescope to advance our knowledge for these key questions.

How are the building blocks of planets assembled from dust and gas?

<strong>How are the building blocks of planets assembled from dust and gas?</strong>

How do planets reach their current orbits after forming in a disk around a star?

<strong><strong>How do planets reach their current orbits after forming in a disk around a star?</strong></strong>

Can we find evidence that planets orbiting in the habitable zones of stars have liquid water in their atmospheres?

<strong><strong>Can we find evidence that planets orbiting in the habitable zones of stars have liquid water in their atmospheres?</strong></strong>

What atmospheric signatures might indicate biological processes and how do we distinguish between geological and biological atmospheric signatures?

<strong><strong><strong><strong>What atmospheric signatures might indicate biological processes and how do we distinguish between geological and biological atmospheric signatures?</strong></strong></strong></strong>

What is the chemical and physical history of the building blocks that formed Earth?

<strong>What is the chemical and physical history of the building blocks that formed Earth?</strong>

Do comets and other distant icy bodies contain clues to our origins?

<strong>Do comets and other distant icy bodies contain clues to our origins?</strong>

How can we improve techniques for detecting and characterizing exoplanets?

<strong>How can we improve techniques for detecting and characterizing exoplanets?</strong>

what can small bodies from our solar system as well as those from outside it, tell us about the early history and formation of planetary systems?

what can small bodies from our solar system as well as those from outside it, tell us about the early history and formation of planetary systems?

Key Findings / Discoveries : Other Worlds

01

Helping to define the dividing line between planets and stars

Webb directly imaged 29 Cygni b, an object 15 times more massive than Jupiter. In order to be able to classify it as a star or a planet, astronomers needed to figure out how it was formed because stars and planets result from two different processes. Webb detected the presence of carbon dioxide and carbon monoxide, providing strong evidence that 29 Cygni b is rich in heavier elements, consistent with objects that formed from a proto-planetary disk. Additionally, astronomers were able to determine that the angle of this planet’s orbit is aligned with the axis around which its star spins. This is similar to what we see in our own solar system. Scientists are gathering data on three other targets that have similar profiles to 29 Cygni b, which will give us more insight into how the largest of planets form.

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02

The most comprehensive view of Saturn to date

Webb teamed up with the Hubble Space Telescope, observing Saturn in complementary wavelengths of light to give us a richer, more layered understanding of its atmosphere. These images were each captured in 2024, just 14 weeks apart from each other.

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03

Observations of an exoplanet whose composition defies explanation

Scientists are using Webb to investigate PSR J2322-2650b, an oddball of an exoplanet. It is a Jupiter-mass gaseous, lemon-shaped planet that may or may not contain diamonds at its core, orbiting a pulsar, which itself is a rapidly-spinning, dense remnant of a star that is the mass of the Sun but the size of a city. Instead of common molecules like water, methane, and carbon dioxide, in its atmosphere, Webb saw molecular carbon. Molecular carbon rarely exists at the temperatures seen on this planet and why it is there (or even how a planet like this forms around a pulsar) remains an open question.

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04

The strongest evidence for an atmosphere on a rocky exoplanet

Webb detected the strongest evidence yet for an atmosphere on a rocky planet outside our solar system. Findings suggest ultra-hot super-Earth TOI-561 b is surrounded by a thick blanket of gases above a global magma ocean. The results of this recent study help explain the planet’s unusually low density and challenge the current knowledge that relatively small planets that are close to their stars are unable to sustain atmospheres. A relatively small iron core, and mantle made of rock that is not as dense as rock within Earth, could explain the planet’s low density. This planet’s composition could be representative of planets that formed when the universe was relatively young.

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05

Measurements of a moon-forming disk around a massive planet

Webb provided the first direct measurements of the potential for moon-formation in a carbon-rich disk encircling a giant exoplanet, which is itself orbiting a red dwarf star. Though no moons themselves are detected in the Webb data, the chemical and physical properties of the disk make it a possible construction yard for moons. Jupiter’s four major moons all orbit in the same plane, so it is thought that they condensed out of a similar flattened disk billions of years ago. Looking at other systems “under construction” will help us better understand how moons form around planets.

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06

A long awaited look at the TRAPPIST-1 planets

The TRAPPIST-1 system has seven rocky Earth-sized planets with several of them in their star’s habitable zone. As of 2026, Webb has published results about planets b, c, d, and e.

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07

New evidence for a planet around our closest solar twin

Webb’s observations from its Mid-Infrared Instrument (MIRI) are providing the strongest evidence to date of a gas giant orbiting Alpha Centauri A. If confirmed, this planet would be the closest to Earth that orbits in the habitable zone (the distance from a star at which liquid water could exist on orbiting planets’ surfaces) of a Sun-like star. The planet candidate however, is a gas giant, meaning that it would not support life as we know it.

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08

Support for long-proposed process of planet formation

Scientists have long theorized that icy pebbles drift from the outer to the inner regions of a disk, delivering water and solids that then form planets. New data from Webb demonstrates this process in action. Pebbles were expected to go through compact disks more efficiently, allowing for greater delivery of water and solids to inner planets. Webb’s results confirmed these expectations by revealing excess cool water in the compact disks, compared with the larger disks.

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09

New moon discovered around Uranus

Webb discovered an unknown moon orbiting the seventh planet, expanding its known satellite family to 29. The newly discovered moon is estimated to be just six miles (10 km) in diameter, assuming it has a similar reflectivity (albedo) to Uranus’ other small satellites. We haven’t seen this moon before now, likely due to its small size rendering it invisible to earlier missions or telescopes. Of the planet's now 29 moons, this one is the 14th member of the system of moons orbiting inward of the largest moons, Miranda, Ariel, Umbriel, Titania, and Oberon.

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10

One of the coldest exoplanets imaged to date

14 Her c, which is a chilly 26 degrees F (-3 C) in temperature is one of the coldest exoplanets imaged to date. It’s hard to capture objects that are this faint - but Webb was up to the challenge. Webb is also giving us insight into a planetary system that astronomers have deemed abnormal, chaotic, and strange, with planets in misaligned orbits. Planets b and c don’t orbit in the same plane the way our planets do, with Planet c’s orbiting its star some 1.4 billion miles away in an extremely elliptical orbit (on average 15 times farther from the Sun than Earth) putting it somewhere between Saturn and Uranus if it were in our solar system.

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11

Webb’s first discovery of a planet using direct imaging

TWA 7, a young, nearby star, is Webb's first discovery of a planet using direct imaging. With a mass similar to Saturn, it’s also the lightest exoplanet yet seen using this technique! It happens to be oriented nearly face-on to us, giving us a good view of the star’s debris disk, and the planet nestled within a gap in one of its three dust rings. The dust rings had been previously observed by ground-based telescopes and Webb’s Mid-Infrared Instrument (MIRI) was able to image the planet itself. Astronomers are excited that Webb is able to capture images of planets with masses similar to those in our solar system - this will help us better understand our own home in the cosmos.

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12

Revealing the origin of our Solar System and glimpses of others

Webb is giving us a comprehensive look at the composition of small bodies across the solar system. These studies are revealing details about how and where these objects formed enabling a glimpse at our solar system’s baby pictures. Additionally, we are now revealing details about other planetary systems as they eject some small bodies that seem to find their way closer to us and thorough investigations on their chemistry and dynamics is telling us the history and story of where they came from.

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This image shows the planetary system HR 8799. The background is black. At the center there is a symbol representing a star labeled HR 8799. The star’s light is blocked. There are four exoplanets, which look like fuzzy dots, pictured surrounding the star. Furthest from the star is a fuzzy, faint blue dot, labeled b, at the 10 o’clock position. At the 1 o’clock position, second furthest from the star is a blueish-white fuzzy dot labeled c. Just below that is an orange dot labeled e. At the 4 o’clock position, still near the star, is another fuzzy white dot labeled d.

NASA’s James Webb Space Telescope has provided the clearest look yet at the iconic multi-planet system HR 8799. The observations detected carbon dioxide in each of the planets, which provides strong evidence that the system’s four giant planets formed much like Jupiter and...

Image: NASA, ESA, CSA, STScI, Laurent Pueyo (STScI), William Balmer (JHU), Marshall Perrin (STScI)

Introduction: Other Worlds

The Dawn of Exoplanet Science

The first planetary system found outside our own came as a complete surprise—not around a main sequence star like our Sun, but orbiting a pulsar. This unexpected discovery in 1992 marked the beginning of a revolution in astronomy.

Since then, we have discovered thousands of exoplanets in every conceivable type of star system, fundamentally changing our perspective on planetary systems. In 1990, the only planets and moons we knew of orbited the Sun. Today, we have come to the realization that planets are in fact quite common throughout the universe, opening up entirely new fields of scientific research and new potential for putting our cosmic experience in context.

An image labeled James Webb Space Telescope: Fomalhaut. An orange oval extends from the 7 o’clock to 1 o’clock positions. It features a prominent outer ring, a darker gap, an intermediate ring, a narrower dark gap, and a bright inner disk. At the center is a ragged black spot where the detector is saturated. At left, a series of labels with lines indicate the individual features. From inside to outside, they are: inner disk, inner gap, intermediate belt, outer gap, outer ring, and halo. In the outer ring at about the 3 o’clock position, a white box surrounds a clump of material labeled great dust cloud. Two pullouts to the lower right show the clump in blue, using data at 23 microns, and orange, using data at 25.5 microns.

This image of the Fomalhaut system, captured by Webb’s Mid-Infrared Instrument (MIRI), shows compass arrows, scale bar, and color key for reference. Labels indicate the various structures. At right, a great dust cloud is highlighted and pullouts show it in two infrared...

Image: NASA, ESA, CSA; Image Processing: András Gáspár (University of Arizona), Alyssa Pagan (STScI); Science: András Gáspár (University of Arizona)

A Universe of Unexpected Worlds

Our first reference for alien worlds begins with our own cosmic neighborhood. Earth, the only known world with life, has vast liquid water oceans and a substantial atmosphere, orbiting within what we've come to recognize as an organized system: rocky planets closest to the Sun (Mercury, Venus, Earth, Mars), giant planets farther out (Jupiter, Saturn, Uranus, Neptune), and broad fields of smaller bodies—the rocky Asteroid Belt and icy Kuiper Belt.

Spacecraft missions have revealed that even the moons of our solar system are greatly varied worlds. Jupiter's Europa has an icy crust laced with fissures that release water vapor, suggesting a subsurface ocean beneath. Its moon Io stands as the most volcanically active world in the solar system. Saturn's moon Titan harbors large surface lakes of liquid methane, creating an alien landscape unlike anything on Earth.

But astronomers have discovered that the universe contains far more exotic worlds than even our diverse solar system suggests. There are Jupiter-sized gas giants orbiting so close to their stars they complete an orbit in days, massive rocky "super-Earths" with no analog in our system, and "warm Neptunes" in configurations we never imagined. Proxima Centauri b, the closest known exoplanet, orbits within the complex triple-star system Alpha Centauri, challenging our assumptions about planetary formation.

In Depth: What is Webb Studying and How?

Decoding Planetary Origins

The incredible diversity of worlds we observe results from the equally diverse conditions under which they form. As nebulae of gas and dust swirl around young protostars, the building blocks of planetary systems can assemble in countless ways. The original composition of these stellar nurseries determines what kinds of stars, planets, moons, and small bodies will emerge as complex processes transform microscopic dust grains into vast worlds.

Webb's ability to observe deep into the mid-infrared allows astronomers to peer through the dusty protoplanetary disks that would otherwise block visible light, providing unprecedented insights into planet formation. Scientists can now study the very disks around other stars where planets are currently forming, measuring their composition and structure to understand how planetary systems develop.

Webb is also revealing more about brown dwarfs, cosmic objects that are like a bridge between planets and stars. Brown dwarfs are not massive enough for their cores to sustain hydrogen fusion like full-fledged stars do, but their formation process is like that of stars, not planets. Observing star and planet formation stages may help explain how and why some masses of matter become small stars, others gas giant planets, and some brown dwarfs.

Brown dwarfs are dim and much cooler than stars, and thus difficult to observe. When they are very young, however, they are still relatively warmer and brighter than the obscuring, dense dust and gas that surrounds them. Webb’s extreme sensitivity to infrared light can pierce these dense, dusty regions and see the faint infrared glow from young brown dwarfs.

Our Solar System Laboratory

While Webb searches for distant worlds, it also serves as an invaluable tool for studying our own solar system with unprecedented detail. Webb complements NASA's fleet of planetary missions, rovers, and ground-based observatories by providing unique infrared capabilities that reveal features invisible to other instruments.

On Mars, Webb can detect trace organic molecules in the atmosphere that might indicate past or present biological activity, conducting global atmospheric studies that complement the detailed local investigations of rovers and landers. Webb's observations will verify and expand upon findings from surface missions, searching for molecules that could be signs of life.

In the outer solar system, Webb continues the legacy of missions like Cassini, studying seasonal weather patterns on the giant planets and their moons. The telescope can characterize small bodies across the farthest reaches of the solar system —these icy relics preserve conditions from our solar system's earliest days and may contain crucial clues about Earth's origins and prebiotic chemistry throughout our planetary system .

Webb's unprecedented sensitivity enables detailed compositional studies of asteroids and other small bodies, revealing mineralogical features that Earth-based telescopes cannot detect. These observations help scientists understand the chemical and physical history of the building blocks that came together to form our terrestrial planets.

The infographic shows Webb’s image of Jupiter at the left. The planet is striated with swirling horizontal stripes of neon turquoise, periwinkle, and cream. Below the planet, the NIRCam filters and their respective colors assigned are listed – F164N in blue, F212N in green, and F360M in red. On the right side of the infographic, there are 8 separate images. Two of those images are horizontal and span the entire right half of the infographic. The top horizontal image is labeled F212N 10:52 UT and the bottom is labeled F212N 20:55 UT. They are zoomed-in pullouts from a section of Jupiter’s equator—outlined in a white box on the image of the planet on the left. Both of these images are white and grey with horizontal wispy clouds. There are 6 smaller boxes in between the two horizontal images—3 rows of 2. The first column of the boxes is outlined in orange, the second column purple and the third yellow. Each of the smaller images correspond to orange, purple, and yellow boxes placed along the horizontal images.

Researchers using NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) have discovered a high-speed jet stream sitting over Jupiter’s equator, above the main cloud decks. At a wavelength of 2.12 microns, which observes between altitudes of about 12-21 miles (20-35 km).

Image: NASA, ESA, CSA, STScI, Ricardo Hueso (UPV), Imke de Pater (UC Berkeley), Thierry Fouchet (Observatory of Paris), Leigh Fletcher (University of Leicester), Michael Wong (UC Berkeley), Joseph DePasquale (STScI)

Planetary Atmospheres

Webb can use transmission spectroscopy to characterize the composition of an exoplanet's atmosphere. Transmission spectroscopy compares the light filtered through the exoplanet's atmosphere to the light coming from the parent star.

Different types of chemicals in the atmosphere absorb different colors of the starlight spectrum, so the colors that are missing tell astronomers which atoms and molecules are present. By viewing infrared light with its sensitive spectrographs, Webb can pick up chemical fingerprints that can’t be detected in visible light.

Graphic titled “Hot Gas Giant Exoplanet WASP-39 b Atmosphere Composition” includes the NIRSpec PRISM spectra with an illustration of the planet and its star in the background. The graph shows the amount of light blocked in percent on the y axis versus wavelength of light in microns on the x axis. The y axes range from 2.00 percent (less light blocked) to 2.35 percent (more light blocked). The x axes range from less than 0.1 microns to 5.5 microns. Data points are plotted as white circles with grey error bars. A curvy blue line represents a best-fit model. The graph features labeled highlights for sodium, water, carbon monoxide, and carbon dioxide.

WASP-39 b is a hot gas giant exoplanet that orbits its star closer than Mercury orbits the Sun. The y-axis shows the percentage of light blocked by the planet and its atmosphere, while the x-axis shows the wavelength of light that's being observed in microns. The detection of carbon dioxide in this planet's transmission spectrum demonstrated Webb's capacity to find this molecule in the thinner atmospheres of smaller, rocky planets, especially across the 3- to 5.5-micron range. Download the WASP-39 b PRISM spectra.

Credit: NASA, ESA, CSA, J. Olmsted (STScI).

The NIRSpec Integral Field Unit

Webb’s Near-Infrared Spectrograph (NIRSpec) can give scientists data about the chemical composition of an exoplanet atmosphere, but it also has a special mode that combines imaging and spectroscopy. The Integral Field Unit (IFU) hardware can capture an image of the field of view along with individual spectra of each pixel in the field of view.

IFU observations allow astronomers to investigate the variations in properties of an object, such as composition, temperature, and motion. Essentially this allows scientist to map their observations spatially. Here is an example. This image of Uranus is not a high-resolution image from our primary camera - it is actually a map of the movement of auroras in the atmosphere made using IFU data.

For the first time, an international team of astronomers have mapped the vertical structure of Uranus’s upper atmosphere, uncovering how temperature and charged particles vary with height across the planet. Using Webb’s NIRSpec instrument, the team detected the faint glow from molecules high above the clouds. These unique data provide the most detailed portrait yet of where the planet’s auroras form, how they are influenced by its unusually tilted magnetic field, and how Uranus’s atmosphere has continued to cool over the past three decades. The results offer a new window into how ice-giant planets distribute energy in their upper layers. Two bright auroral bands were detected near Uranus’s magnetic poles, together with reduced emission and ion density in part of the region between the two bands (a feature likely linked to transitions in magnetic field lines).

Credit: ESA/Webb, NASA, CSA, STScI, P. Tiranti, H. Melin, M. Zamani (ESA/Webb)

Latest Images : Other Worlds Theme - Exoplanets & Brown Dwarfs

The image below is a SLIDESHOW of all NASA published imagery in the Other Worlds Theme focusing on exoplanets & brown dwarfs.
USAGE: Hover over the image to see the image title and controls. Click the arrows to move through the slide show, click the image to go to a detail page with more info and the ability to download the image at various resolutions.

Brown Dwarfs in IC 348 (NIRCam Image)

Latest Images : Other Worlds Theme - Our Solar System

The image below is a SLIDESHOW of all NASA published imagery in the Other Worlds Theme focusing on Our Solar System.
USAGE: Hover over the image to see the image title and controls. Click the arrows to move through the slide show, click the image to go to a detail page with more info and the ability to download the image at various resolutions.

New Moon Discovered Orbiting Uranus Using NASA’s Webb Telescope

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