NASA discovers older, bigger cousin planet to Earth

NASA’s Kepler mission has confirmed the discovery of a new near-Earth-size planet in the habitable zone around a Sun-like star.

Artist's concept comparing Earth (left) to Kepler-452b (right) (credit: NASA/JPL-Caltech/T. Pyle)

Artist’s concept comparing Earth (left) to Kepler-452b (right) (credit: NASA/JPL-Caltech/T. Pyle)

Perhaps a bit ‘unromantically’ called Kepler-452b, this new Earth-like planet is the smallest planet discovered, to date, which orbits a star in the zone where conditions are optimal for liquid water to exist on the surface. Kepler-452b is 60 percent larger in diameter than Earth and while its mass and composition have not been determined yet, there are good chances it could be rocky. It is located 1,400 light-years away from us in the constellation of Cygnus.

It orbits – in a 385-day year – a so-called G2-type star, like our Sun, from which it is only 5 percent farther than Earth is from our Sun. The star which Kepler-452b is orbiting has been named Kepler-452; it is 6 billion years old – i.e. 1.5 billion years older than our Sun – has the same temperature, and is 20 percent brighter and 10 percent larger in diameter.

“We can think of Kepler-452b as an older, bigger cousin to Earth, providing an opportunity to understand and reflect upon Earth’s evolving environment,” said Jon Jenkins at NASA, who led the team that discovered Kepler-452b. “It’s awe-inspiring to consider that this planet has spent 6 billion years in the habitable zone of its star; longer than Earth. That’s substantial opportunity for life to arise, should all the necessary ingredients and conditions for life exist on this planet,” Jenkins added.

In addition to Kepler-452b, the team of researchers has discovered a total of 521 new exoplanet candidates, which now account to an overall number of 4,696. For now these are only “candidate exoplanets” as follow-up observations are required to verify whether or not they can be classified as actual planets. Amongst these new planet candidates, twelve were found to have diameters 1-2 times that of Earth and orbit in their star’s habitable zone. Of these, nine orbit stars that are similar to our Sun in size and temperature.

The discovery of so many potential new exoplanets has been possible thanks to improved, automatic observations. “We’ve been able to fully automate our process of identifying planet candidates, which means we can finally assess every transit signal in the entire Kepler dataset quickly and uniformly,” said Jeff Coughlin, at the SETI Institute in Mountain View, California, who led the analysis of the new candidate exoplanets. “This gives astronomers a statistically sound population of planet candidates to accurately determine the number of small, possibly rocky planets like Earth in our Milky Way galaxy.”

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Carlo Bradac

Carlo Bradac

Dr Carlo Bradac is a Research Fellow at the University of Technology, Sydney (UTS). He studied physics and engineering at the Polytechnic of Milan (Italy) where he achieved his Bachelor of Science (2004) and Master of Science (2006) in Engineering for Physics and Mathematics. During his employment experience, he worked as Application Engineer and Process Automation & Control Engineer. In 2012 he completed his PhD in Physics at Macquarie University, Sydney (Australia). He worked as a Postdoctoral Research Fellow at Sydney University and Macquarie University, before moving to UTS upon receiving the Chancellor Postdoctoral Research and DECRA Fellowships.

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