Using a potent NASA space telescope to scan the skies for planets like our own where life might exist, astronomers said on Thursday they have found the most Earth-like candidates yet.
Two of the five planets orbiting a sun-like star called Kepler-62 are squarely in what astronomers call the habitable zone — not too hot, not too cold and possibly bearing water, researchers said in the journal Science.
“These two are our best candidates that might be habitable,” said William Borucki, Kepler science principal investigator at NASA’s Ames Research Center.
The two planets are slightly larger than ours and at least a couple of billion years older.
The first, 62e, is about 40 percent larger than Earth.
It might be warm, maybe even a waterworld, and it may experience flashes of lightning, Borucki said.
The second, 62f, is about 60 percent larger than our planet and orbits its star every 267 days, close to Earth’s annual trajectory of 365 days.
The planet may have polar caps, significant land masses and liquid water, Borucki said.
Both are orbiting a seven-billion-year-old star about 1,200 light years from Earth in the constellation Lyra.
They are close enough to their star to be warm, but not so near as to boil the oceans. They are far enough to maintain the likelihood of water without freezing the seas solid, Borucki said.
Scientists do not yet know if their surfaces are rocky or watery, or if they have atmospheres that could sustain life, but their location and size suggest they “could plausibly be composed of condensible compounds and be solid, either as a dry, rocky super-Earth or one composed of a significant amount of water,” the study said.
Other studies have indicated that planets with a radius under 1.6 times that of the Earth, like these two, “have been found to have densities indicative of a rocky composition.”
Astronomers detected the planets by observing their star dim when the planets pass in front of it, in what is known as a “transit.”
“These are the most similar objects to Earth that we have found yet,” said Justin Crepp, assistant professor of physics at the University of Notre Dame.
All together, the latest findings add seven new planets — four of which are outside the habitable zone — to the tally that Kepler has found so far, totaling more than 2,700 candidates and confirmed planets.