A rocky planet about 25 light-years from Earth is drawing fresh attention after astronomers revised its size and orbit. The world, GJ 3378b, now appears to be roughly 2.3 times Earth's mass, nearly half the earlier estimate, making it a stronger candidate for a solid surface rather than a dense, Venus-like envelope.
The updated analysis, published in the Astrophysical Journal and led by Paul Robertson of UC Irvine, also shortened the planet's orbital period from 25 days to 21. That places it in a range where liquid water could potentially exist, depending on the planet's atmosphere and surface conditions.
Reading a Star's Motion
Because the planet cannot be seen directly, researchers measured its presence through the subtle wobble it causes in its host star. This method, known as radial velocity detection, is especially effective when paired with infrared instruments designed for cool red dwarf stars.
The team used the Habitable-zone Planet Finder on the Hobby-Eberly Telescope at McDonald Observatory in Texas to capture the faint signal. According to the researchers, precision is the key to identifying low-mass planets around dim stars.
Red dwarfs are central to this search because they make up most stars in the Milky Way. Their habitable zones sit much closer in than the Sun's, which means planets can complete short orbits while still receiving the right amount of energy for possible surface water.
GJ 3378b still raises open questions, especially about whether it has retained an atmosphere. Future observatories such as the Giant Magellan Telescope, the Extremely Large Telescope, and NASA's proposed Habitable Worlds Observatory are expected to push this kind of planet study further, potentially revealing atmospheric clues and signs of habitability. Each refined measurement brings astronomers closer to mapping the most promising worlds in our cosmic neighborhood, shaping the next era of exoplanet discovery.