Some New Planets Discovered By the Kepler Space Telescope May Be False Alarms

Saturday, 12 May 2018 - 6:23PM
Space
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Saturday, 12 May 2018 - 6:23PM
Some New Planets Discovered By the Kepler Space Telescope May Be False Alarms
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NASA Ames/ W Stenzel
Since its launch back in 2009, the Kepler Space Telescope has done nothing but look out for signs of exoplanets, which are simply planets in other solar systems.

And it has been busy, with NASA having used Kepler's findings to confirm 1,284 exoplanets as of last year. But some critics are drawing attention to what NASA's official definition of "confirmed exoplanet" means in the context of Kepler, and it's beginning to look like a portion of these may not be planets after all. 

At an initial glance, NASA's approach to Kepler does seem legitimate, and it's very likely that most of its findings are indeed actually planets in other solar systems (they're certainly not uncommon). Just like every other space telescope, Kepler looks for transit events - small dips in the brightness of distant stars that suggest something is passing in front of it.

Much of the time, when a transit event is discovered, another telescope will attempt to verify it and once confirmed, scientists can begin studying it in more detail to see what exactly the exoplanet is made of. The problem is, Kepler is so prolific in its planet-hunting that NASA doesn't have the resources to independently verify each planet anymore.



According to a paper just published in the Astronomical Journal, NASA originally used this method with Kepler, but eventually switched to another method where they mathematically verify the chances that one of Kepler's findings is indeed a planet. If the transit event seems to be 99 percent likely that it's a planet, than NASA identifies it as such. If not, it's likely just interstellar noise or something else blocking a small piece of a star.

The study's concern is that none of this takes into account errors with Kepler's instruments - and with anything as sophisticated as an observatory floating in space, some moving parts will always be prone to flaws and occasional errors. Especially so when Kepler is showing signs of age.

As an example, they look at the exoplanet Kepler 452b, which made headlines back in 2015 for being a larger "cousin" to Earth, which is huge news for astronomers who are constantly on the lookout for Earth-like planets in other solar systems. But taking into account the Kepler telescope's potential for errors, the chances of Kepler 452b being a real planet now shift to 92 percent an maximum, and 16 percent at minimum.

Either way, it no longer meets NASA's official standards, which would mean they'd need independent verification with another telescope to see for certain. Considering Kepler has found almost 4,302 transit events, the odds that 1,284 of them are exoplanets could now come into question.

Again, it's likely that most of the planets Kepler identified are real, but there could easily be some false positives coming from the telescope. While NASA has just launched their new Transiting Exoplanet Survey Satellite (TESS) into space, the true replacement for Kepler will be the James Webb Space Telescope, which is delayed and may not launch until at least 2020.

So in the meantime, there's plenty of other verified exoplanet hunters besides Kepler, and they seem to have some more credibility right now.
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