- \n
- GJ 3378b is a super-Earth exoplanet<\/strong> about 25 light-years away. It is about twice the size of Earth.<\/li>\n
- The planet is in the habitable zone<\/strong> of its red dwarf star, where liquid water could exist. But does it have an atmosphere?<\/li>\n
- We don\u2019t know yet if GJ 3378b has an atmosphere.<\/strong> If it does, it could possibly be rather Earth-like and habitable.<\/li>\n<\/ul>\n
EarthSky isn\u2019t powered by billionaires. We\u2019re powered by you.<\/strong> Support EarthSky\u2019s 2026 Donation Campaign and help keep science accessible. <\/p>\n
Nearby super-Earth planet could be habitable<\/h3>\n
Astronomers have discovered a new Earth-like planet that might be a good candidate for habitability. The exoplanet, GJ 3378b, is about twice the size of Earth and 25 light-years away. The team of researchers, led by the University of California, Irvine, said on June 30, 2026, that the planet is in the habitable zone of its red dwarf star. That means it could have liquid water on its surface, if it has an atmosphere. So this planet could<\/em> be habitable. But we don\u2019t have enough data to know that yet.<\/p>\n
The size of the planet makes it a super-Earth. Those are rocky planets that are larger than Earth but smaller than Neptune.<\/p>\n
The team used the Habitable-zone Planet Finder instrument on the Hobby-Eberly Telescope at the McDonald Observatory in Texas to observe the planet\u2019s host star. Astronomers first identified GJ 3378b as a candidate planet in 2024. And now, it is a confirmed planet.<\/p>\n
The new observations also refined the planet\u2019s orbit from 25 days to 21. That\u2019s a lot less than Earth\u2019s at 365 days, but the planet also orbits much closer to its red dwarf star, which is smaller and cooler than our sun.<\/p>\n
The researchers published the peer-reviewed details of the new discovery in The Astrophysical Journal<\/em> on June 30, 2026.<\/p>\n
In the habitable zone<\/h3>\n
GJ 3378b is in the habitable zone of its star, a good location for potential habitability. That\u2019s the region where temperatures could allow liquid water to exist on a planet\u2019s surface, though whether it actually does also depends on its own atmosphere and composition. The planet does receive a suitable amount of radiation from its star, as lead author Paul Robertson at UC Irvine stated:<\/p>\n
\n
This super-Earth gets about 90% of the radiation from its host star as Earth gets from its sun, so it\u2019s right in the sweet spot.<\/p>\n
This one\u2019s exciting. It\u2019s one of our closest cosmic neighbors. 25 light-years sounds like a long way, but the Milky Way is about 100,000 light-years across, so in that respect it\u2019s our next-door neighbor.<\/p>\n<\/blockquote>\n
He added:<\/p>\n
\n
Our mantra is \u2018follow the water.\u2019 It\u2019s the one thing every known living thing on Earth needs, so that\u2019s the first thing we look for when trying to find environments that could sustain life.<\/p>\n<\/blockquote>\n
![\"Man](\"https:\/\/earthsky.org\/upl\/2026\/07\/Paul-Robertson-UC-Irvine.jpg\")
Paul Robertson at UC Irvine led the new study about GJ 3378b and its potential habitability. Image via UC Irvine.<\/figcaption><\/figure>\n Does GJ 3378b have an atmosphere?<\/h3>\n
What we know so far about GJ 3378b sounds promising in terms of habitability. But there\u2019s still one big question: does the planet have an atmosphere? We don\u2019t know yet. It\u2019s in the habitable zone, but it\u2019s also at the edge of what scientists call the cosmic shoreline. If a planet is outside of that boundary, closer to the star, then radiation from the star could strip away the planet\u2019s atmosphere. This is common with planets close to red dwarf stars.<\/p>\n
But GJ 3378b is right at the edge of this boundary. And we don\u2019t know yet if it still has an atmosphere or if it had one and lost it. Ideally, the planet would have a thin, evolved atmosphere like Earth\u2019s \u2014 nitrogen-based, not the thick, hydrogen-dominated \u201cprimordial\u201d atmosphere a planet is born with. A more Earth-like atmosphere could maintain liquid water, as Robertson explained:<\/p>\n
\n
If you scale the Earth down to the size of an apple, its atmosphere would be about as thick as the skin of the apple. That\u2019s just enough to maintain the kinds of surface pressures where you can have liquid water. It\u2019s enough that there\u2019ll be breathable air, and it provides maybe a little bit of protection from the harsh radiation environment of space.<\/p>\n<\/blockquote>\n
Searching for signs of life on GJ 3378b<\/h3>\n
Right now, we don\u2019t know if GJ 3378b is even habitable, let alone has life of any kind. But scientists want to take a closer look. NASA\u2019s planned Habitable Worlds Observatory, for example, scheduled to launch sometime in the 2040s, would be able to take direct images of the planet. That, or perhaps other telescopic observations before then, will help determine whether GJ 3378b could actually support life. And then scientists could search for biosignatures, chemical or other signs of life in the planet\u2019s atmosphere.<\/p>\n
Gogod James, a UC Irvine student, said:<\/p>\n
\n
If a planet in the habitable zone has a proper atmosphere, we can justify further research looking for biosignatures, liquid water or other signs of life that require both an atmosphere and the right amount of heating from the host star.<\/p>\n<\/blockquote>\n
![\"Earth-like](\"https:\/\/earthsky.org\/upl\/2026\/07\/GJ3378b-artist-concept-NASA.jpeg\")
View larger. | This is another artist\u2019s concept of a super-Earth exoplanet. Image via NASA.<\/figcaption><\/figure>\n The search for biosignatures continues<\/h3>\n
As Michael Endl, an astronomer at UT Austin, noted:<\/p>\n
\n
The ultimate goal is biosignatures. We really want to know, \u2018Are we alone in the universe?\u2019 We are still in the reconnaissance phase of our solar neighborhood, trying to find the planets around the nearest stars because those will be the easiest ones to detect a biosignature on. This planet brings us one step closer to knowing all of our neighbors and, ultimately, which might be hospitable for life.<\/p>\n<\/blockquote>\n
For Robertson, the prospect of searching for life on GJ 3378b is something to savor:<\/p>\n
\n
I think that\u2019s just too much fun.<\/p>\n<\/blockquote>\n
Bottom line: Astronomers have gotten a closer look at the nearby super-Earth GJ 3378b. It could be habitable, if it has an atmosphere.<\/p>\n
Source: A Revised Mass and Period for the Habitable Zone super-Earth GJ 3378 b: A Planet Straddling the Cosmic Shoreline<\/p>\n
Via UC Irvine<\/p>\n
Via McDonald Observatory<\/p>\n
Read more: Nearby super-Earth is super-hot and airless<\/p>\n
Read more: Powerful magnetic fields on super-Earths could boost chances of life<\/p>\n
<\/div>\n
\n - The planet is in the habitable zone<\/strong> of its red dwarf star, where liquid water could exist. But does it have an atmosphere?<\/li>\n