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NASA Establishes New Class of Astrophysics Missions, Selects Studies
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Explore Hubble Science Hubble Space Telescope NASA’s Hubble Sees White… Hubble Home Overview About Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & Benefits Hubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts Science Hubble Science Science Themes Science Highlights Science Behind Discoveries Universe Uncovered Hubble’s Partners in Science AI and Hubble Science Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations Science Operations Astronaut Missions to Hubble Hubble vs Webb Team Hubble Team Career Aspirations Hubble Astronauts Multimedia Images Videos Sonifications Podcasts e-Books Online Activities 3D Hubble Models Lithographs Fact Sheets Posters Hubble on the NASA App Glossary News Hubble News Social Media Media Resources More 35th Anniversary Online Activities 5 Min Read NASA’s Hubble Sees White Dwarf Eating Piece of Pluto-Like Object
This artist’s concept shows a white dwarf surrounded by a large debris disk. Debris from pieces of a captured, Pluto-like object is falling onto the white dwarf. Credits:
Artwork: NASA, Tim Pyle (NASA/JPL-Caltech) In our nearby stellar neighborhood, a burned-out star is snacking on a fragment of a Pluto-like object. With its unique ultraviolet capability, only NASA’s Hubble Space Telescope could identify that this meal is taking place.
The stellar remnant is a white dwarf about half the mass of our Sun, but that is densely packed into a body about the size of Earth. Scientists think the dwarf’s immense gravity pulled in and tore apart an icy Pluto analog from the system’s own version of the Kuiper Belt, an icy ring of debris that encircles our solar system. The findings were reported on September 18 in the Monthly Notices of the Royal Astronomical Society.
The researchers were able to determine this carnage by analyzing the chemical composition of the doomed object as its pieces fell onto the white dwarf. In particular, they detected “volatiles” — substances with low boiling points — including carbon, sulphur, nitrogen, and a high oxygen content that suggests the strong presence of water.
“We were surprised,” said Snehalata Sahu of the University of Warwick in the United Kingdom. Sahu led the data analysis of a Hubble survey of white dwarfs. “We did not expect to find water or other icy content. This is because the comets and Kuiper Belt-like objects are thrown out of their planetary systems early, as their stars evolve into white dwarfs. But here, we are detecting this very volatile-rich material. This is surprising for astronomers studying white dwarfs as well as exoplanets, planets outside our solar system.”
This artist’s concept shows a white dwarf surrounded by a large debris disk. Debris from pieces of a captured, Pluto-like object is falling onto the white dwarf. Artwork: NASA, Tim Pyle (NASA/JPL-Caltech) Only with Hubble
Using Hubble’s Cosmic Origins Spectrograph, the team found that the fragments were composed of 64 percent water ice. The fact that they detected so much ice meant that the pieces were part of a very massive object that formed far out in the star system’s icy Kuiper Belt analog. Using Hubble data, scientists calculated that the object was bigger than typical comets and may be a fragment of an exo-Pluto.
They also detected a large fraction of nitrogen – the highest ever detected in white dwarf debris systems. “We know that Pluto’s surface is covered with nitrogen ices,” said Sahu. “We think that the white dwarf accreted fragments of the crust and mantle of a dwarf planet.”
Accretion of these volatile-rich objects by white dwarfs is very difficult to detect in visible light. These volatile elements can only be detected with Hubble’s unique ultraviolet light sensitivity. In optical light, the white dwarf would appear ordinary.
About 260 light-years away, the white dwarf is a relatively close cosmic neighbor. In the past, when it was a Sun-like star, it would have been expected to host planets and an analog to our Kuiper Belt.
Like seeing our Sun in future
Billions of years from now, when our Sun burns out and collapses to a white dwarf, Kuiper Belt objects will be pulled in by the stellar remnant’s immense gravity. “These planetesimals will then be disrupted and accreted,” said Sahu. “If an alien observer looks into our solar system in the far future, they might see the same kind of remains we see today around this white dwarf.”
The team hopes to use NASA’s James Webb Space Telescope to detect molecular features of volatiles such as water vapor and carbonates by observing this white dwarf in infrared light. By further studying white dwarfs, scientists can better understand the frequency and composition of these volatile-rich accretion events.
Sahu is also following the recent discovery of the interstellar comet 3I/ATLAS. She is eager to learn its chemical composition, especially its fraction of water. “These types of studies will help us learn more about planet formation. They can also help us understand how water is delivered to rocky planets,” said Sahu.
Boris Gänsicke, of the University of Warwick and a visitor at Spain’s Instituto de Astrofisica de Canarias, was the principal investigator of the Hubble program that led to this discovery. “We observed over 500 white dwarfs with Hubble. We’ve already learned so much about the building blocks and fragments of planets, but I’ve been absolutely thrilled that we now identified a system that resembles the objects in the frigid outer edges of our solar system,” said Gänsicke. “Measuring the composition of an exo-Pluto is an important contribution toward our understanding of the formation and evolution of these bodies.”
The Hubble Space Telescope has been operating for more than three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
To learn more about Hubble, visit: https://science.nasa.gov/hubble
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White Dwarf Accreting Icy Object (Illustration)
This artist’s concept shows a white dwarf surrounded by a large debris disk. Debris from pieces of a captured, Pluto-like object is falling onto the white dwarf.
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Last Updated Sep 18, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Contact Media Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov
Ann Jenkins
Space Telescope Science Institute
Baltimore, Maryland
Ray Villard
Space Telescope Science Institute
Baltimore, Maryland
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Hubble Space Telescope Astrophysics Division Dwarf Planets Goddard Space Flight Center The Kuiper Belt White Dwarfs
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Science Paper: Discovery of an icy and nitrogen-rich extra-solar planetesimal, PDF (674.84 KB)
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Preparations for Next Moonwalk Simulations Underway (and Underwater)
It’s been 30 years since the discovery of the first planet around another star like our Sun. With every new discovery, scientists move closer to answering whether there are other planets like Earth that could host life as we know it. NASA/JPL-Caltech The milestone highlights the accelerating rate of discoveries, just over three decades since the first exoplanets were found.
The official number of exoplanets — planets outside our solar system — tracked by NASA has reached 6,000. Confirmed planets are added to the count on a rolling basis by scientists from around the world, so no single planet is considered the 6,000th entry. The number is monitored by NASA’s Exoplanet Science Institute (NExScI), based at Caltech’s IPAC in Pasadena, California. There are more than 8,000 additional candidate planets awaiting confirmation, with NASA leading the world in searching for life in the universe.
See NASA's Exoplanet Discoveries Dashboard “This milestone represents decades of cosmic exploration driven by NASA space telescopes — exploration that has completely changed the way humanity views the night sky,” said Shawn Domagal-Goldman, acting director, Astrophysics Division, NASA Headquarters in Washington. “Step by step, from discovery to characterization, NASA missions have built the foundation to answering a fundamental question: Are we alone? Now, with our upcoming Nancy Grace Roman Space Telescope and Habitable Worlds Observatory, America will lead the next giant leap — studying worlds like our own around stars like our Sun. This is American ingenuity, and a promise of discovery that unites us all.”
Scientists have found thousands of exoplanets (planets outside our solar system) throughout the galaxy. Most can be studied only indirectly, but scientists know they vary widely, as depicted in this artist’s concept, from small, rocky worlds and gas giants to water-rich planets and those as hot as stars. NASA’s Goddard Space Flight Center The milestone comes 30 years after the first exoplanet was discovered around a star similar to our Sun, in 1995. (Prior to that, a few planets had been identified around stars that had burned all their fuel and collapsed.) Although researchers think there are billions of planets in the Milky Way galaxy, finding them remains a challenge. In addition to discovering many individual planets with fascinating characteristics as the total number of known exoplanets climbs, scientists are able to see how the general planet population compares to the planets of our own solar system.
For example, while our solar system hosts an equal number of rocky and giant planets, rocky planets appear to be more common in the universe. Researchers have also found a range of planets entirely different from those in our solar system. There are Jupiter-size planets that orbit closer to their parent star than Mercury orbits the Sun; planets that orbit two stars, no stars, and dead stars; planets covered in lava; some with the density of Styrofoam; and others with clouds made of gemstones.
“Each of the different types of planets we discover gives us information about the conditions under which planets can form and, ultimately, how common planets like Earth might be, and where we should be looking for them,” said Dawn Gelino, head of NASA’s Exoplanet Exploration Program (ExEP), located at the agency’s Jet Propulsion Laboratory in Southern California. “If we want to find out if we’re alone in the universe, all of this knowledge is essential.”
Searching for other worlds
Fewer than 100 exoplanets have been directly imaged, because most planets are so faint they get lost in the light from their parent star. The other four methods of planet detection are indirect. With the transit method, for instance, astronomers look for a star to dim for a short period as an orbiting planet passes in front of it.
To account for the possibility that something other than an exoplanet is responsible for a particular signal, most exoplanet candidates must be confirmed by follow-up observations, often using an additional telescope, and that takes time. That’s why there is a long list of candidates in the NASA Exoplanet Archive (hosted by NExScI) waiting to be confirmed.
“We really need the whole community working together if we want to maximize our investments in these missions that are churning out exoplanets candidates,” said Aurora Kesseli, the deputy science lead for the NASA Exoplanet Archive at IPAC. “A big part of what we do at NExScI is build tools that help the community go out and turn candidate planets into confirmed planets.”
The rate of exoplanet discoveries has accelerated in recent years (the database reached 5,000 confirmed exoplanets just three years ago), and this trend seems likely to continue. Kesseli and her colleagues anticipate receiving thousands of additional exoplanet candidates from the ESA (European Space Agency) Gaia mission, which finds planets through a technique called astrometry, and NASA’s upcoming Nancy Grace Roman Space Telescope, which will discover thousands of new exoplanets primarily through a technique called gravitational microlensing.
Many telescopes contribute to the search for and study of exoplanets, including some in space (artists concepts shown here) and on the ground. Doing the work are organizations around the world, including ESA (European Space Agency), CSA (Canadian Space Agency), and NSF (National Science Foundation). NASA/JPL-Caltech Future exoplanets
At NASA, the future of exoplanet science will emphasize finding rocky planets similar to Earth and studying their atmospheres for biosignatures — any characteristic, element, molecule, substance, or feature that can be used as evidence of past or present life. NASA’s James Webb Space Telescope has already analyzed the chemistry of over 100 exoplanet atmospheres.
But studying the atmospheres of planets the size and temperature of Earth will require new technology. Specifically, scientists need better tools to block the glare of the star a planet orbits. And in the case of an Earth-like planet, the glare would be significant: The Sun is about 10 billion times brighter than Earth — which would be more than enough to drown out our home planet’s light if viewed by a distant observer.
NASA has two main initiatives to try overcoming this hurdle. The Roman telescope will carry a technology demonstration instrument called the Roman Coronagraph that will test new technologies for blocking starlight and making faint planets visible. At its peak performance, the coronagraph should be able to directly image a planet the size and temperature of Jupiter orbiting a star like our Sun, and at a similar distance from that star. With its microlensing survey and coronagraphic observations, Roman will reveal new details about the diversity of planetary systems, showing how common solar systems like our own may be across the galaxy.
Additional advances in coronagraph technology will be needed to build a coronagraph that can detect a planet like Earth. NASA is working on a concept for such a mission, currently named the Habitable Worlds Observatory.
More about ExEP, NExScI
NASA’s Exoplanet Exploration Program is responsible for implementing the agency’s plans for the discovery and understanding of planetary systems around nearby stars. It acts as a focal point for exoplanet science and technology and integrates cohesive strategies for future discoveries. The science operations and analysis center for ExEP is NExScI, based at IPAC, a science and data center for astrophysics and planetary science at Caltech. JPL is managed by Caltech for NASA.
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Last Updated Sep 17, 2025 Related Terms
Exoplanets Exoplanet Discoveries Gas Giant Exoplanets Jet Propulsion Laboratory Kepler / K2 Nancy Grace Roman Space Telescope Neptune-Like Exoplanets Super-Earth Exoplanets Terrestrial Exoplanets TESS (Transiting Exoplanet Survey Satellite) The Search for Life Explore More
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