Super Earths Found Abundant in Distant Orbits Across the Galaxy

Super Earths Found Abundant in Distant Orbits Across the Galaxy
by Clarence Oxford
Los Angeles CA (SPX) Apr 28, 2025

An international collaboration, including researchers from the Center for Astrophysics | Harvard and Smithsonian (CfA), has reported the discovery of a planet about twice the size of Earth orbiting its star at a distance beyond that of Saturn's orbit around the Sun.

The findings offer further evidence that planetary systems can differ greatly from the familiar layout of our Solar System.

"We found a 'super Earth' - meaning it's bigger than our home planet but smaller than Neptune - in a place where only planets thousands or hundreds of times more massive than Earth were found before," said Weicheng Zang, a CfA Fellow and lead author of the study published in the latest issue of Science.

This newly discovered super Earth is particularly significant because it emerges from a broader survey examining planetary mass distributions relative to their host stars. The team's work provides new insights into the diversity of planetary populations across the Milky Way.

Employing the microlensing technique - where the gravity of an intervening planet magnifies the light from a background object - the researchers detected planets positioned between Earth's and Saturn's orbital distances. The study, the most extensive of its kind, tripled the number of known planets found via microlensing and reached down to planets about eight times smaller than previous microlensing surveys could detect.

Data was collected through the Korea Microlensing Telescope Network (KMTNet), a global array with facilities in Chile, South Africa, and Australia, offering near-continuous sky coverage.

"The current data provided a hint of how cold planets form," explained Professor Shude Mao of Tsinghua University and Westlake University in China. "In the next few years, the sample will be a factor of four larger, and thus we can constrain how these planets form and evolve even more stringently with KMTNet data."

Our Solar System hosts four small rocky planets close to the Sun and four large gas giants farther out. Prior searches for exoplanets, notably via the Kepler and TESS missions and radial velocity methods, revealed that other star systems often possess an array of small to large planets within Earth's orbit.

The CfA team's new results extend this knowledge to outer planetary regions, indicating that super-Earths are widespread well beyond Earth's orbit. "This measurement of the planet population from planets somewhat larger than Earth all the way to the size of Jupiter and beyond shows us that planets, and especially super-Earths, in orbits outside the Earth's orbit are abundant in the Galaxy," stated co-author Jennifer Yee of the Smithsonian Astrophysical Observatory, part of the CfA.

"This result suggests that in Jupiter-like orbits, most planetary systems may not mirror our Solar System," added co-author Youn Kil Jung from the Korea Astronomy and Space Science Institute, which operates KMTNet.

The team is also investigating the relative abundance of super Earths compared to Neptune-sized planets. Their analysis suggests that super Earths are at least as numerous as Neptune-sized planets in wide orbits.

Research Report:Microlensing events indicate that super-Earth exoplanets are common in Jupiter-like orbits