A new study led by astronomers from the Center for Astrophysics | Harvard & Smithsonian (CfA) has revealed that planets larger than Earth—known as super-Earths—are not only common, but often exist much farther from their stars than previously thought.
One recently discovered planet, about twice the size of Earth, orbits its star at a distance even greater than Saturn’s orbit around the Sun.
This discovery adds to the growing evidence that planetary systems across our galaxy can be quite different from our own. In our solar system, the outer planets like Jupiter and Saturn are massive gas giants.
Until now, scientists thought that similarly distant planets in other systems would also be huge. But this new finding shows that much smaller planets, like super-Earths, can also exist in these far-out orbits.
Lead author Weicheng Zang, a fellow at CfA, explained that this discovery came from the largest microlensing study of its kind.
Microlensing is a technique that detects distant planets by observing how their gravity bends light from a background star, making it appear brighter.
This method is especially good at spotting planets located far from their host stars—something that other techniques often struggle to do.
The team used data from the Korea Microlensing Telescope Network (KMTNet), which has three telescopes positioned in Chile, South Africa, and Australia.
This global setup allows for continuous monitoring of the sky, helping astronomers catch rare microlensing events.
With this powerful setup, the study included nearly three times more planets than previous microlensing surveys and identified planets up to eight times smaller than what had been detected before.
According to Professor Shude Mao, a co-author from Tsinghua and Westlake Universities in China, the results offer new clues about how cold, distant planets form.
Over the next few years, researchers expect to expand their planet sample even further, which will help refine our understanding of how different types of planets come into being and evolve.
In our own solar system, the planets follow a clear pattern: small, rocky planets like Earth close to the Sun, and large gas giants farther out. But other planetary systems appear to be more diverse.
Previous searches using telescopes like Kepler and TESS have found small and medium planets closer to their stars, sometimes in arrangements that don’t resemble our solar system at all.
Now, with this new data, scientists see that even the outer reaches of other systems can host smaller planets like super-Earths, not just gas giants.
These findings challenge the idea that our solar system’s structure is typical. Instead, they suggest that planets—especially super-Earths—are abundant throughout the galaxy, even in orbits far from their stars.
