Exciting’ Earth-Like Planet Found

 Astronomers discover an exciting habitable planet just 25 light-years away 

A potentially habitable rocky world has been found in the habitable zone around a red dwarf just 25 light-years from us. However, faced with a hostile wind of radiation from its host star, it remains unclear whether this new exoplanet supports an atmosphere, or the possibility of life. Nevertheless, astronomers are celebrating the discovery. "This one's exciting," said Paul Robertson of the University of California, Irvine. "It's one of our closest cosmic neighbors. Twenty-five light years sounds like a long way, but the Milky Way is about 100,000 light years across, so in that respect it's our next-door neighbor."  Astronomers are offering another promising target in the search for life beyond Earth. The newly identified planet, named GJ 3378b, is a potentially rocky world, according to NASA, which orbits within the habitable zone of its host star, where temperatures may allow liquid water to exist on its surface. The discovery highlights how potentially habitable worlds close to the sun may be more common than previously thought. Some of the important factors are as follows:-

GJ 3378b has a minimum mass just over twice Earth's. Scientists classify planets of this size as super-Earths, which may have rocky surfaces and conditions worth studying.

The WIYN 3.5-meter telescope at the Kitt Peak National Observatory near Tucson, Arizona, one of the two telescopes was used to discover exoplanet GJ 3378b. 

Planet Facts Distance: 25 light-years from Earth

Location: Northern constellation of Camelopardalis

Orbit Time: 21.45 days

Star Type: Faint red dwarf star (GJ 3378)

The planet receives about 90% of the starlight Earth receives from the sun. That places it in the habitable zone, where liquid water could potentially exist.

The planet was found using the Hobby-Eberly Telescope at McDonald Observatory, Texas and the WIYN Telescope at Kitt Peak National Observatory, Arizona.

NASA’s planned Habitable Worlds Observatory, expected to launch in the 2040s, is designed to image nearby Earth-like exoplanets, such as GJ 3378b, to determine whether they have atmospheres capable of supporting life.

The planet, designated GJ 3378b, orbits the faint red dwarf star in the constellation of Camelopardalis, the Giraffe. It was discovered in 2024 by French astronomers using the Canada–France–Hawaii Telescope in Mauna Kea, but American astronomers have revised those initial findings, revealing that the planet is possibly more like Earth than we realized. The planet has a minimum mass just over twice that of Earth and orbits its star at a distance that causes it to receive almost the same amount of starlight as Earth does. The planet joins a growing population of potential hosts for life in the nearby universe. All we know for sure is the mass and the orbit of GJ 3378b. We do not yet know whether it is like Earth or not – it could have land and sea and clouds and life, or it could be airless and cratered. The planet is not seen to transit, or pass in front of its star, blocking its light from our vantage point. Instead, GJ 3378b was detected by the effects of its gravity tugging on its parent star. This causes the star to wobble around the center of mass that it shares with the planet, a wobbling that is betrayed by a Doppler shift in the star's light which can be measured by its spectra, the wavelengths of light that it emits.

Although 25 light-years may seem distant, astronomers consider GJ 3378b to be one of Earth’s nearest known potentially habitable neighbors. Although it cannot be seen even with a large backyard telescope, GJ 3378b, and its host red dwarf star, are in the northern constellation of Camelopardalis. When it was discovered in 2024, its mass was measured to be 5.26 times the mass of Earth, putting it in mini-Neptune territory of being a larger, mostly gaseous world. However, by taking a second look at the planet using two different telescopes, Robertson's team was able to show that the planet's true mass is 2.3 times the mass of Earth. This means that it is closer to being a rocky super-Earth instead. Furthermore, the same observations found that GJ 3378b's orbital period is 21 days, not the 25 days that had originally been measured. This means that the planet is closer to the star than had been thought, sitting comfortably within the habitable zone where temperatures will be suitable for liquid water on the surface of a planet with an atmosphere. So from that point of view, the chance of GJ 3378b being habitable, if not inhabited, seems fair. "This super-Earth gets about 90% of the radiation from its host star that Earth gets from its sun, so it's right in the sweet spot," said Robertson. 

One significant problem, however, is that red dwarfs spit out harmful torrents of radiation in fierce gusts of their stellar winds, which can strip away a planet's atmosphere. This raises the question, does GJ 3378b even have an atmosphere? Currently there is no way to tell. The James Webb Space Telescope (JWST) has been probing for atmospheres around other rocky worlds orbiting red dwarfs, such as those in the TRAPPIST-1 system. It does so by transit spectroscopy, where an atmosphere wrapped around a planet absorbs some of the star's light filtering through it, leaving dark absorption lines in the star's spectrum. Unfortunately, GJ 3378b does not transit its star. This means that astronomers will have to wait until the 2040s, when NASA's Habitable Worlds Observatory will hopefully launch, to answer the question of whether GJ 3378b really does have an atmosphere or not. Still, astronomers are hopeful. GJ 3378b is right on the edge of the zone where planets are expected to be seriously battered by radiation, meaning it could have escaped the worst. If so, there might be more than just an atmosphere for the Habitable Worlds Observatory to discover. Relatively cool red dwarf stars make up 70% of all stars, instantly making them an important target in the search for life outside our solar system. However, red dwarfs like GJ 3378 are also relatively small and dim, making it difficult to detect orbiting planets. The astronomers used the radial velocity method, in which telescopes detect a subtle wobble in the host star which reveals the gravitational pull of a planet in orbit. The wobble can be used to calculate the planet’s mass and orbit.

"The ultimate goal is biosignatures," said University of Texas at Austin astronomer Michael Endl. "We really want to know, are we alone in the universe? 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." GJ 3378b is in the habitable zone of its star, so could have liquid water on its surface. “Our mantra is ‘follow the water,’” said Robertson. “It’s the one thing every known living thing on Earth needs, so that’s the first thing we look for when trying to find environments that could sustain life.” However, whether GJ 3378b has an atmosphere capable of supporting stable surface conditions is yet to be determined. The planet lies near what astronomers call the “cosmic shoreline,” a threshold where intense radiation from its host star can gradually strip away a planet’s atmosphere. Mars is believed to have experienced a similar process billions of years ago.

The next step will require more advanced space telescopes capable of directly studying the planet’s atmosphere. If GJ 3378b is found to have the right atmospheric conditions, it could become a stronger candidate for future life-detection studies. Red dwarf stars can blast harsh radiation and strip away gas layers. The planet does not cross in front of its star from Earth's view, meaning current telescopes cannot easily check for an atmosphere. Scientists hope to use future equipment like the planned Habitable Worlds Observatory in the 2040s to learn more.