A possible ‘super-Earth’ located in the habitable zone

Sen—NASA researchers announced today the tantalizing discovery by the Kepler Space Telescope team of a massive world that may resemble Earth, orbiting in the habitable zone of a distant Sun-like star.

The planet, designated Kepler-452b, is about 1,400 light years away, and is located in the direction of the constellation Cygnus. It orbits a G2 star ten per cent larger than the diameter of our own Sun once every 385 days. Estimates suggest that Kepler-452b may be 60 per cent larger than Earth, and five times more massive.

The discovery was part of the 5th data release from the original Kepler survey, which ended in 2011. The Kepler mission found a new lease on life after the failure of several reaction wheels in 2012 and 2013. Kepler is now carrying out an extended K2 survey pointing along the ecliptic, as it uses the solar wind pressure as a third stabilizing ‘reaction wheel’.

“On the 20th anniversary year of the discovery that proved other (main sequence) suns host planets, the Kepler exoplanet explorer has discovered a planet and star which most closely resemble Earth and our Sun,” said the associate administrator of NASA’s Science Mission Directorate John Grunsfeld in a press release.

This brings the number of planets discovered orbiting in the habitable zones of their systems to 11, and Kepler’s total number of confirmed planets to 1,030. The total number of confirmed exoplanets currently sits at 1,934. Though the first exoplanet around an ordinary star was found in 1995, the first exoplanet system was actually discovered orbiting a pulsar in 1992.



A comparison of stellar surface temperatures vs energy received by similiar 'super-Earth's' orbiting in the habitable zone, to include Kepler-452b: Image credit: NASA/N. Batalha and W. Stenzel

A star's habitable zone is also referred to as the "Goldilocks zone", a region that is not too hot, and not too cold, but just right for surface liquid water to exist.

Ground-based observations carried out by the McDonald Observatory in Texas, the Whipple Observatory in Arizona, and the W. M. Keck Observatory in Hawaii were used to verify the discovery. The host star is about two billion years older and 20 per cent more luminous than our Sun is currently, meaning that Kepler-452b, large or small, receives close to the same amount of energy from its host star as the Earth.

Of course, some caveats are in order. The team mentioned during the course of the interview that no direct mass measurement was made of the transiting exoplanet, but the size and mass of Kepler-452b was instead inferred by statistical size distributions seen in other systems. Many social media users also pointed out that a paper released earlier this year asserted that planets 1.6 times the size of the Earth most likely aren’t rocky.

And I wouldn’t build an interstellar ark to head off there just yet. At 1,400 light years, it would take the New Horizons spacecraft, moving at over eight miles a second, over 32 million years to reach Kepler-452b. For now, Kepler-452b will join the growing ranks of possible Earth-like worlds, and puts us one step closer towards knowing just how common—or rare—our own world may be in the cosmos.