By Yue Xing, Janet Huang
In 2018, after nine years of exploration, NASA’s Kepler Space Telescope concluded its mission, having discovered thousands of exoplanets and provided a wealth of data for scientific analysis. Using the Kepler Candidate Planet Catalog, astronomers improved methods for measuring stellar characteristics, resulting in more accurate calculations of celestial orbital periods and sizes.
This refinement led to the discovery of the Kepler-385 planetary system, a rare seven-planet system — one of the few known systems with more than six confirmed planets. Among previously discovered systems, the well-known TRAPPIST-1, located 39.13 light-years from Earth, is similar, with both systems second only to the eight-planet Solar System and Kepler-90 in terms of confirmed planets.
Kepler-385 is located approximately 4,670 light-years from Earth. Its host star is a Sun-like star, about 1.1 times the Sun’s size and roughly 5 percent hotter. The system’s seven planets are all scorching-hot worlds, each larger than Earth but smaller than Neptune. Some were confirmed as early as 2014, while the innermost planets, Kepler-385 b and Kepler-385 c, are thought to be rocky planets with thin atmospheres.
Specifically:
- Kepler-385 b has a mass of about 12.8 Earth masses, a diameter 2.7 times that of Earth, and an orbital period of 10 days, orbiting only slightly farther from its star than Earth does from the Sun. It is the smallest and closest planet to the host star.
- Kepler-385c has a mass of 13.2 Earth masses, a diameter also 2.7 times Earth’s, and completes its orbit in 15 days along a nearly perfect circular path.
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The remaining five planets have radii approximately twice that of Earth, suggesting they may have dense atmospheres.
For a long time, astronomers have hoped to find planets with Earth-like environments as potential sites for human habitation. While these planets initially seemed to hold promise as habitable super-Earths, further research revealed that they orbit too close to their host star — even closer than Mercury is to the Sun.
Jack Lissauer, an astronomer at NASA’s Ames Research Center in Moffett Federal Airport, California, explained: “All these planets are subjected to far stronger ‘frying’ radiation than any planets in our Solar System.” The extreme heat and intense stellar radiation make them inhospitable to human life.
This discovery also highlights that our Solar System is unusual, as it did not develop into a system like Kepler-385. The unique structure of our system may have been crucial in creating the conditions necessary for life on Earth, offering a profound reminder of the preciousness of our planet.
