NASA scientists call it Earth cousin and not twin because it circles a star smaller and dimmer than our sun
.jpg "Although the size of Kepler-186f is known, its mass and composition are not. (Photo credit: NASA)")
There is exciting news for those looking for and wondering about potentially habitable planets outside our solar system. Scientists have discovered what they claim is the most Earth-like planet detected till date.
The planet, Kepler 186f, detected by NASA's orbiting Kepler telescope, is circling a red dwarf star, Kepler 186, some 500 light years away (one light year equals about 9.5 trillion km) and exists in the “Goldilocks zone” where it's neither too hot nor too cold. The planet, which is about 10 per cent larger than Earth, may very well have liquid water that makes life possible on Earth, scientists said. This is because it resides at the outer edge of the habitable temperature zone around its star — the sweet spot where lakes, rivers or oceans may exist without freezing solid or boiling away.
“Kepler 186f is the first validated, Earth-size planet in the habitable zone of another star,” said Elisa V Quintana of the SETI Institute and NASA’s Ames Research Center in Mountain View, California at a news conference on Thursday. “It has the right size and is at the right distance to have properties similar to our home planet.” Quintana said she considers the planet to be more of an "Earth cousin" than a twin because it circles a star that is smaller and dimmer than our sun. While Earth revolves around the sun in 365 days, this planet completes an orbit of its star every 130 days.
Kepler-186f is part of a system of five planets, all of which are roughly Earth's size. However, the other planets are too close to their star to support life.
Kepler 186f, named after NASA's Kepler planet finding mission, is too far away for astronomers to ascertain its mass, or if it has an atmosphere and supports life.
Kepler telescope examines Space for subtle changes in brightness that indicate an orbiting planet is crossing in front of a star. From those changes, scientists calculate a planet's size and make certain inferences about its makeup.
Since its launch in 2009, Kepler has confirmed 961 planets, but only a few dozen are in the habitable zone. Most are giant gas balls like Jupiter and Saturn, and not ideal places for life.
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