NASA has now confirmed 6,000 exoplanets — a dazzling collection of alien worlds ranging from fiery giants and lava oceans to planets with clouds of gemstones or the density of Styrofoam.
This milestone not only highlights the staggering variety of worlds beyond our solar system but also marks humanity’s growing ability to find and study them.
NASA Reaches 6,000 Confirmed Exoplanets
NASA’s official count of confirmed exoplanets, meaning planets that orbit stars beyond our solar system, has now reached 6,000. New discoveries are added gradually by scientists worldwide, so there is no single planet designated as the 6,000th. The tally is maintained by NASA’s Exoplanet Science Institute (NExScI) at Caltech’s IPAC in Pasadena, California. More than 8,000 additional candidates are still awaiting confirmation, as NASA continues to lead the global effort to uncover signs of life beyond Earth.
“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.”
From First Discovery to Today
The 6,000 milestone comes three decades after the first exoplanet was confirmed around a Sun-like star in 1995. (Before that, a few planets had been detected orbiting stars that had already burned through their fuel and collapsed.) Scientists estimate there are billions of planets in the Milky Way, but spotting them remains difficult. As the catalog of confirmed exoplanets grows, researchers not only identify intriguing individual worlds but also gain perspective on how planetary systems compare with our own.
In our solar system, rocky planets and giant planets are balanced in number. Beyond it, rocky planets appear far more common. Researchers have also uncovered planetary types completely unlike anything nearby: Jupiter-sized worlds that orbit closer to their star than Mercury does to the Sun, planets circling two stars or none at all, dead-star companions, lava worlds, bodies so lightweight they resemble Styrofoam, and even planets with skies filled with gemstone clouds.
“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.”
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. Credit: NASA/JPL-Caltech
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.
Collaboration and Accelerating Discoveries
“We really need the whole community working together if we want to maximize our investments in these missions that are churning out exoplanet 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.
The Future: Finding Earth-Like Planets
At NASA, the future of exoplanet science will focus on discovering rocky planets similar to Earth and studying their atmospheres for biosignatures — any characteristic, element, molecule, substance, or feature that can serve 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.
Roman Telescope and the Hunt for Habitable Worlds
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 (ExEP) leads the agency’s efforts to discover and understand planetary systems around nearby stars. Serving as the focal point for exoplanet science and technology, ExEP develops unified strategies that guide both current missions and future discoveries, with a strong emphasis on identifying potentially habitable worlds.
The program’s science operations and analysis hub is the NASA Exoplanet Science Institute (NExScI), located at IPAC (Caltech’s astrophysics and planetary science data center) in Pasadena, California. NExScI provides the tools, data, and coordination needed for the global research community to study exoplanets. Both ExEP and NExScI operate under the management of Caltech’s Jet Propulsion Laboratory (JPL) for NASA, ensuring scientific rigor and technological innovation remain at the forefront of exoplanet exploration.
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