Gliese 12 b: Earth-Sized Exoplanet Discovered, Fueling Habitable World Debate
October 20, 2025
Astronomers discover Gliese 12 b, a temperate, Earth-sized exoplanet ideal for atmosphere analysis by JWST.
In a significant advancement for exoplanetary science, an international team of astronomers has announced the discovery of Gliese 12 b, a temperate, Earth-sized planet orbiting a nearby star. Located just 40 light-years away, this new world presents one of the most promising targets to date for atmospheric analysis, potentially bringing humanity a step closer to determining whether life could exist beyond our solar system.
A Cosmic Neighbor: The Gliese 12 System
Gliese 12 b orbits a cool red dwarf star named Gliese 12, situated in the constellation Pisces. Red dwarfs are the most common type of star in the Milky Way, making planets around them key subjects in the search for habitable worlds. The star's relative calm, compared to other active red dwarfs, enhances the possibility that Gliese 12 b could have retained an atmosphere over cosmic timescales.
Key Characteristics and Discovery Method
The exoplanet was initially identified using data from NASA's Transiting Exoplanet Survey Satellite (TESS), which detects the slight dimming of a star's light as a planet passes in front of it. Follow-up observations from ground-based telescopes confirmed its existence and planetary nature. Analysis reveals a world comparable in size to Earth and Venus, completing an orbit around its star every 12.8 days.
- Proximity: Located just under 40 light-years from Earth, making it one of the closest known transiting, temperate, Earth-sized exoplanets.
- Size: Slightly smaller than Earth, with a radius comparable to that of Venus.
- Estimated Temperature: Scientists calculate an equilibrium temperature of 42°C (107°F), assuming it has no atmosphere. The actual surface temperature is highly dependent on atmospheric presence and composition.
The Crucial Question: Is There an Atmosphere?
The potential for habitability hinges on whether Gliese 12 b has an atmosphere. A substantial atmosphere could regulate its surface temperature, potentially allowing for liquid water, while a runaway greenhouse effect, like that on Venus, would render it scorching hot. Conversely, a lack of an atmosphere would leave it a barren, airless rock. This makes Gliese 12 b a crucial natural laboratory for studying planetary evolution.
Gliese 12 b represents a prime target to study whether Earth-sized planets orbiting cool stars can retain their atmospheres and, by extension, support the conditions necessary for liquid water. It's a vital piece of the puzzle.
Future Research: A Prime Target for JWST
The planet's proximity and its star's characteristics make it an ideal candidate for further study with the James Webb Space Telescope (JWST). Using a technique called transmission spectroscopy, JWST can analyze starlight filtering through the planet's atmosphere (if one exists) to detect key molecules like water vapor, carbon dioxide, and methane, providing definitive clues about its climate and potential habitability.
The discovery of Gliese 12 b is more than just finding another dot in the sky; it is a critical step forward in our quest to understand planetary diversity and the prevalence of potentially habitable environments in our galaxy. Future observations will undoubtedly reshape our understanding of what it takes for a world to be truly Earth-like.
Frequently Asked Questions
Gliese 12 b's combination of Earth-like size, potentially moderate surface temperature, and close proximity to Earth (40 light-years) makes it one of the best-known candidates for atmospheric study to assess habitability.
It was first detected as a potential candidate by NASA's Transiting Exoplanet Survey Satellite (TESS), which observed the planet passing in front of its star. The discovery was then confirmed through further observations by ground-based telescopes.
Its habitability is currently unknown. It depends critically on whether the planet has an atmosphere and, if so, its composition. Without an atmosphere, it would be too cold for liquid water, but a thick atmosphere could make it too hot. The James Webb Space Telescope will investigate this.
The next major step is to use the James Webb Space Telescope (JWST) to perform transmission spectroscopy. This will allow scientists to determine if an atmosphere is present and analyze its chemical makeup for signs of water, methane, and other biosignatures.