Free Astronomy Magazine May-June 2025

7 MAY-JUNE 2025 ASTRO PUBLISHING T he MAROON-X in- strument is attached to the Gemini North telescope, one half of the International Gemini Observatory, funded in part by the U.S. National Science Foundation and operated by NSF NOIR- Lab, where it dissects light from the telescope to capture information about faraway planets. [International Gemini Observatory/NOIRLab/ NSF/AURA/J. Bean] “great white whale” for planet hunters; several times over the past century, groups have announced evidence that suggested planets around Barnard’s Star, only for them to be subsequently disproved. But these latest findings give a much larger degree of confidence than any previous result. “We observed at different times of night on different days. They’re in Chile; we are in Hawai’i. Our teams didn’t coordinate with each other at all,” says Basant. “That gives us a lot of assurance that these aren’t phantoms in the data.” The four planets, each only about 20 to 30% the mass of Earth, are so close to their home star that they zip all the way around it in a matter of days. The fourth planet is the least massive planet discovered to date using the radial velocity technique. The team hopes this will spark a new era of finding more and more sub- Earth exoplanets in the Universe. Most rocky planets found so far are much larger than Earth, and they appear to be fairly similar through- out the Milky Way Galaxy. But there are reasons to think that smaller ex- oplanets have more widely varied compositions. As scientists find more of them, they can begin to tease out more information about how these planets form and what makes them likely to have habitable conditions. “The U.S. National Science Founda- tion is collaborating with the astron- omy community on an adventure to look deeper into the Universe to de- tect planets with environments that might resemble Earth’s,” says Martin Still, NSF program director for the International Gemini Observatory. “The planet discoveries provided by MAROON-X mounted on Gem- ini North provide a significant step along that journey.” MAROON-X is still a visiting instru- ment at Gemini North. Given its out- standing performance and popular- ity with the user community, it is in the process of being converted to a permanent facility instrument. “This result demonstrates the com- petitive, state-of-the-art capabilities that Gemini offers its user commu- nity. The observatory is in the middle of rejuvenating its instrumentation portfolio and MAROON-X is part of the first wave of new instruments, alongside GHOST on Gemini South and IGRINS-2 on Gemini North,” says Andreas Seifahrt, Associate Director of Development for the Interna- tional Gemini Observatory, co-au- thor of the paper, and member of the team who designed and built MAROON-X. !