Kepler-62e

Lore & Background

Kepler-62e was discovered by NASA's Kepler spacecraft, which observed the dimming of its host star as the planet transited. The detection was based on light curves collected between 13 May 2009 and 17 March 2012, with the discovery announced on April 18, 2013. The planet orbits its star every 122.3 days at a distance of about 0.42 AU, receiving roughly 20% more stellar flux than Earth receives from the Sun. A 2016 study suggested that Kepler-62e and its neighbor Kepler-62f are likely in a 2:1 orbital resonance, meaning for every two orbits of Kepler-62e, Kepler-62f completes one.

The planet's radius of 1.61 times Earth's places it just above the 1.6 Earth-radius threshold above which planets may be more gaseous than rocky, leading to uncertainty about its composition. It may be a mini-Neptune with no definite surface, or a rocky world with a substantial amount of water, possibly completely covered by ocean. Its equilibrium temperature is 270 K, but the higher stellar flux could raise surface temperatures above 350 K, potentially triggering a runaway greenhouse effect and reducing habitability. The estimated mass is 4.5 Earth masses, though the true value cannot be determined; an upper limit of 18.7 Earth masses would imply an implausibly high density.

Reader's Guide

Kepler-62e's significance lies in its position within the habitable zone of its star and its size, which straddles the boundary between rocky super-Earths and gaseous mini-Neptunes. This ambiguity makes it a key target for understanding the transition between terrestrial and volatile-rich planets. The discovery prompted congressional hearings in the U.S. House of Representatives on May 9, 2013, titled 'Exoplanet Discoveries: Have We Found Other Earths?', highlighting its cultural impact. Along with Kepler-62f, it is a focus of SETI search programs.

At a distance of nearly 370 parsecs, Kepler-62e is too remote for current or next-generation telescopes to determine its mass or atmospheric composition. However, future space telescopes such as TESS and CHEOPS will survey nearby stars, and the James Webb Space Telescope and large ground-based observatories may analyze its atmosphere and infer its composition. The Square Kilometer Array could also improve radio observations. The planet's legacy is as a representative of the many super-Earths found in habitable zones, whose true nature—ocean world, mini-Neptune, or something else—remains unresolved.

Did You Know?

• Kepler-62e orbits its star every 122.3 days at a distance of 0.42 AU, slightly farther than Mercury's orbit from the Sun.
• The planet receives about 20% more light from its star than Earth receives from the Sun.
• The planet's radius of 1.61 Earth radii is just above the 1.6 threshold where planets may become more gaseous than rocky.