Kepler scientists announce over 700 new confirmed alien worlds

Scott Sutherland
February 26, 2014

NASA's Kepler Space Telescope has given us some amazing discoveries since it launched in 2009, but now, thanks to a new method of confirming worlds, the Kepler science team has announced the largest addition of confirmed worlds to the mission's database to date.

For over four years, the Kepler Space Telescope stared, unblinking, at a small section of our galaxy, watching over 150,000 stars for signs of planets circling around them. Up until now, scientists examining the data from the telescope have announced the discovery of over 3,800 worlds. Nearly 250 of these 'exoplanet' discoveries have been confirmed by observations by other telescopes, but the vast majority of them — over 3,500 — are still classified as planet candidates. These are blips in the data that could be planets, but they haven't been confirmed yet. With so many candidate worlds being picked out of the data all the time, and still so much data still to go through, but with only a few ground-based telescopes available to confirm these findings, it's created a bottleneck.

This has meant that when planet discoveries were actually announced, they trickled in a few at a time, putting something of a damper on the exciting news that our galaxy harbours billions of planets, potentially even outnumbering the stars. Today, though, the Kepler team announced the largest addition of new confirmed planets ever, adding 715 alien worlds to their database. This brings the total number of confirmed worlds to nearly 1,700.

What opened up the data bottleneck? It was a new method of looking at the data developed by NASA and teams at several universities across the United States. This 'Validation by Multiplicity' method basically looks for multiple transits for the same star, but it has to filter out any instances of binary stars (which can look like planet transits in the data). If a star shows one object transiting, there's a significant chance that object is just another star. However, as the number of objects transiting a star goes up, the chances of those objects being stars goes way down, and the chance of them being planets goes way up.

So, since all of these 715 new confirmed worlds were discovered by this method, they all come from multi-planet systems, orbiting a total of 305 different stars. Several of these are apparently are much like our own solar system.

Also, four of these confirmed super-Earth and Earth-sized worlds have been found to orbit their star inside the habitable zone — the not-too-hot, not-too-cold region where planets can have liquid water on their surface. One of these in particular, called Kepler-296f, is twice the size of Earth, orbiting in the habitable zone of a star that's roughly half the size of our sun. This world could be more like Neptune, with a thick hydrogen-helium atmosphere, or it could be a water-world with a deep ocean covering its entire surface, or it could possibly even be a more Earth-like 'superhabitable world'.

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Besides this incredible new tool for confirming exoplanets, today's announcement held two excellent pieces of news.

The first is that, rather than most of these newly-confirmed planets being massive gas giants, like Jupiter, nearly 95 per cent of them are smaller than the planet Neptune, and the majority are either 'super-Earth' or Earth-sized worlds. With this announcement, the number of Earth-sized worlds has jumped from just a few dozen to over 100.

The second is that these 715 worlds were picked out of only the first two years worth of Kepler data. With two more years worth of candidates left to go through, this method could potentially find hundreds more worlds lurking in the data, several of which will no doubt be Earth-sized. That raises the chances of us discovering a truly Earth-like planet from the glimpses we've already taken into the galaxy, and it also makes it more likely that we'll turn up these kinds of planets in future missions as well.

(Image courtesy: NASA)

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