NASA telescope finds 10 more planets that could have life

NASA centre

It's important to note that NASA's rules for what defines a "planet" are incredibly exacting.

In a press briefing at NASA's Ames Research Center, scientists revealed the "most comprehensive" catalog yet of potential planets in our galaxy, bringing the total to 4,034.

Seven of the 10 newfound Earth-size planets circle stars that are just like ours, not cool dwarf ones that require a planet be quite close to its star for the right temperature.

This artist rendering provided by NASA/JPL-Caltech shows some of the 219 new planet candidates, 10 of which are near-Earth size and in the habitable zone of their star identified by NASA's Kepler space telescope.

The analysis pushes Kepler's tally to 4,034 planet candidates overall, of which 2,335 have been confirmed through additional observation and analysis. Instead of directly spotting individual planets and identifying them with something like high-powered optics, Kepler watches for "transits".

The habitable zone is the range of distances from a star where liquid water - one of the building blocks of life - could pool on the surface of a rocky planet.

With this new data, the catalog suggests that about half of the exoplanets in our galaxy are either gaseous, with no surface, or have such a heavy atmosphere that life as we know it would not be possible.

It's too early to know how common potentially habitable planets are in the galaxy because there are lots of factors to consider including that Kepler could only see planets that move between the telescope vision and its star, said Kepler research scientist Susan Mullally of the SETI Institute in Mountain View, California.

Almost all the planet candidates are in between the sizes of Earth and Neptune. More than 30 of 49 terrestrial candidates have been confirmed orbiting in habitable zones where water can exist as a liquid and life as it's known on Earth could, in theory, exist. But if a planet starts out with more hydrogen, is larger, or forms further out before moving inwards, it may end up as a mini-Neptune.

The Kepler mission only looked at one particular part of the sky, so while it only identified a select number of planets and stars even though there are billions more out there. It's a rocky planet that is only 30 percent wider than Earth and has an orbit of nearly exactly one year.

Until KOI-7711 is verified and earns an official Kepler planet name - a process that requires a different telescope (usually ground-based) to observe it transiting - this is all speculation.

One of Kepler's other big surprises was a profusion of planets intermediate in size between Earth and Neptune. Scientists with the mission expect that Kepler's K2 mission will continue until sometime in 2018.

"I'm looking forward to 2030s", said Courtney Dressing, NASA Sagan Fellow.

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