Earth-Like Planet HD 137010 b Could Be Colder Than Mars | Space News

Astronomers have identified a potential Earth-like exoplanet, HD 137010 b, orbiting a Sun-like star 146 light-years away, but early data suggests it may be even colder than Mars. The discovery, announced February 12, 2026, stems from continued analysis of data collected by NASA’s now-retired Kepler Space Telescope.

The planet candidate, slightly larger than Earth, completes an orbit in roughly one year, placing it within the outer reaches of its star’s habitable zone – the region where liquid water could potentially exist on a planet’s surface. However, HD 137010 b receives less than a third of the heat and light that Earth receives from the Sun, due to its host star, HD 137010, being cooler and dimmer than our own.

Researchers estimate surface temperatures on HD 137010 b could plummet to as low as minus 90 degrees Fahrenheit (minus 68 degrees Celsius). By comparison, the average surface temperature on Mars is around minus 85 degrees Fahrenheit (minus 65 degrees Celsius). This makes the newly discovered planet a particularly intriguing, and frigid, target for further study.

The initial detection of HD 137010 b was made through a single transit – the brief dimming of a star’s light as a planet passes in front of it – observed during Kepler’s K2 mission. This single transit event lasted approximately 10 hours, a duration used to estimate the planet’s orbital period. Confirmation of the planet’s existence requires observing additional transits, a challenging task given the planet’s Earth-like orbital period of roughly 355 days.

The signal from HD 137010 b was initially flagged by citizen scientists participating in the Planet Hunters project, who sift through Kepler data. It was later re-examined by astrophysicist Alexander Venner, during his doctoral research at the University of Southern Queensland, Australia, and now as a postdoctoral researcher at the Max Planck Institute for Astronomy in Heidelberg, Germany. Automated detection algorithms had previously overlooked the signal, as they prioritize multiple transit events.

Despite the potentially harsh conditions, scientists haven’t ruled out the possibility of a more temperate climate. Atmospheric modeling suggests that a dense atmosphere rich in carbon dioxide could trap enough heat to allow for liquid water. Researchers estimate a 40% chance the planet resides within the “conservative” habitable zone and a 51% chance within the broader “optimistic” habitable zone, although acknowledging a roughly 50% probability it orbits outside the habitable zone entirely.

Confirmation of HD 137010 b’s planetary status may approach from future observations by NASA’s Transiting Exoplanet Survey Satellite (TESS) or the European Space Agency’s CHEOPS (CHaracterising ExOPlanets Satellite). The findings were published January 27, 2026, in The Astrophysical Journal Letters in a paper titled “A Cool Earth-sized Planet Candidate Transiting a Tenth Magnitude K-dwarf From K2.”