Selections from 2015: Earth-Sized Planet Found in Star’s Habitable Zone

Editor’s Note: In these last two weeks of 2015, we’ll be looking at a few selections from among the most-downloaded papers published in AAS journals this year. The usual posting schedule will resume after the AAS winter meeting.

Discovery and Validation of Kepler-452b: a 1.6 R⨁ Super Earth Exoplanet in the Habitable Zone of a G2 Star

Published July 2015


Main takeaway:

Transit of Kepler-452b

A phase-folded light curve showing the transit of Kepler-452b. Its transit lasts 10.5 hours, and its period is 385 days. [Jenkins et al. 2015]

A team led by Jon Jenkins (NASA Ames Research Center) announced the discovery and confirmation of Kepler-452b, an exoplanet only 60% larger than Earth and located in the habitable zone of its G2 star. This planet orbits its star at a distance of just over 1 AU, taking 385 days to complete an orbit. Kepler-452b also stands a good chance of being rocky, according to estimates.

Why it’s interesting:

Kepler-452b is the first near-Earth-sized planet to be found in the habitable zone of a Sun-like star — making this the closest analog to the Earth-Sun system found in the Kepler dataset so far.

About the history of the system (and the future of ours?):

The authors estimate that the system is ~6 billion years old, and that Kepler-452b has been in the habitable zone of its star throughout its lifetime — a substantially longer time than Earth has been around and habitable! Kepler-452b’s host star, in addition to being 1.5 billion years older than the Sun, is roughly 10% larger. This system might therefore provide a glimpse of what Earth’s environment may be like in the future, as the Sun slowly expands on its way to becoming a red giant.


Jon M. Jenkins et al 2015 AJ 150 56. doi:10.1088/0004-6256/150/2/56