1,284 new planets: Kepler mission announces largest collection ever discovered

Kepler mission announces largest collection of planets ever discovered
This artist's concept depicts select planetary discoveries made to date by NASA's Kepler space telescope. Credit: NASA/W. Stenzel

NASA's Kepler mission has verified 1,284 new planets – the single largest finding of planets to date.

"This announcement more than doubles the number of confirmed from Kepler," said Ellen Stofan, chief scientist at NASA Headquarters in Washington. "This gives us hope that somewhere out there, around a star much like ours, we can eventually discover another Earth." 

Analysis was performed on the Kepler space telescope's July 2015 planet candidate catalog, which identified 4,302 potential planets. For 1,284 of the candidates, the probability of being a planet is greater than 99 percent – the minimum required to earn the status of "planet." An additional 1,327 candidates are more likely than not to be actual planets, but they do not meet the 99 percent threshold and will require additional study. The remaining 707 are more likely to be some other astrophysical phenomena. This analysis also validated 984 candidates previously verified by other techniques.

"Before the Kepler space telescope launched, we did not know whether exoplanets were rare or common in the galaxy. Thanks to Kepler and the research community, we now know there could be more planets than stars," said Paul Hertz, Astrophysics Division director at NASA Headquarters. "This knowledge informs the future missions that are needed to take us ever-closer to finding out whether we are alone in the universe."

Kepler captures the discrete signals of distant planets – decreases in brightness that occur when planets pass in front of, or transit, their stars – much like the May 9 Mercury transit of our sun. Since the discovery of the first planets outside our solar system more than two decades ago, researchers have resorted to a laborious, one-by-one process of verifying suspected planets.

This latest announcement, however, is based on a statistical analysis method that can be applied to many planet candidates simultaneously. Timothy Morton, associate research scholar at Princeton University in New Jersey and lead author of the scientific paper published in The Astrophysical Journal, employed a technique to assign each Kepler candidate a planet-hood probability percentage – the first such automated computation on this scale, as previous statistical techniques focused only on sub-groups within the greater list of planet candidates identified by Kepler.

"Planet candidates can be thought of like bread crumbs," said Morton. "If you drop a few large crumbs on the floor, you can pick them up one by one. But, if you spill a whole bag of tiny crumbs, you're going to need a broom. This statistical analysis is our broom."

In the newly-validated batch of planets, nearly 550 could be like Earth, based on their size. Nine of these orbit in their sun's habitable zone, which is the distance from a star where orbiting planets can have surface temperatures that allow liquid water to pool. With the addition of these nine, 21 exoplanets now are known to be members of this exclusive group.

"They say not to count our chickens before they're hatched, but that's exactly what these results allow us to do based on probabilities that each egg (candidate) will hatch into a chick (bona fide planet)," said Natalie Batalha, co-author of the paper and the Kepler mission scientist at NASA's Ames Research Center in Moffett Field, California. "This work will help Kepler reach its full potential by yielding a deeper understanding of the number of stars that harbor potentially habitable, Earth-size planets—a number that's needed to design future missions to search for habitable environments and living worlds."

Of the nearly 5,000 total found to date, more than 3,200 now have been verified, and 2,325 of these were discovered by Kepler. Launched in March 2009, Kepler is the first NASA mission to find potentially habitable Earth-size planets. For four years, Kepler monitored 150,000 stars in a single patch of sky, measuring the tiny, telltale dip in the brightness of a star that can be produced by a transiting planet. In 2018, NASA's Transiting Exoplanet Survey Satellite will use the same method to monitor 200,000 bright nearby stars and search for planets, focusing on Earth and Super-Earth-sized.


Explore further

Kepler marks 1,000th exoplanet discovery, uncovers more small worlds in habitable zones

More information: "False Positive Probabilities for All Kepler Objects of Interest: 1,284 Newly Validated Planets and 428 Likely False Positives," Timothy D. Morton, Stephen T. Bryson, Jeffrey L. Coughlin, Jason F. Rowe, Ganesh Ravichandran, Erik A. Petigura, Michael R. Haas & Natalie M. Batalha, 2016 May 10, Astrophysical Journal iopscience.iop.org/article/10. … 7/0004-637X/822/2/86 , Preprint: www.astro.princeton.edu/~tdm/koi-fpp/ms.pdf
Journal information: Astrophysical Journal

Provided by NASA
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May 11, 2016
Planets! *Lots* of planets!

And a new, fast method to cull planets from candidates!

Still no Earth analog though, but the statistics on small planets is confirmed and improved. (I.e. they are likely the most frequent, but they are the hardest to see.)

May 11, 2016
"This gives us hope that somewhere out there, around a star much like ours, we can eventually discover another Earth."

What does that even mean?

- Very similar size and/or surface gravity? OK. No problem
- Has temperatures that can sutstain water in all three states? OK I can see that
- Does so throughout its entire orbit? Tricky.
- Has right atmospheric pressure for our lungs to even work? Unlikely.
- Has breathable atmosphere mix (80/20 mix of nitrogen and oxygen - which is NOT a natural equilibrium BTW - as well as no poisonous gases)? Not bloody likely.

So if you're thinking that humans will, in the future, go to other planets and walk around on the surface without a full EVA suit like in SciFi movies: Better forget that notion immediately.

...unless massive terraforming and/or massive self alteration become a reality (and in the latter case you're stuck to one planet,also)

May 11, 2016
"Has breathable atmosphere mix . . . Not bloody likely."

The answer depends on your scale. Within 10 light years, very unlikely, within 10 billion light years, it is very likely. So how far to the next "breathable" atmosphere? Very far is a good guess, but even if the gases there were perfect, the forward and reverse contamination issues probably mean we would need an EVA suit anyway.

All this suggests terraforming is in our future. We already know that most worlds are incompatible and we may want to tread lightly, if at all, on the rare few that are compatible.

May 11, 2016
The answer depends on your scale. Within 10 light years, very unlikely, within 10 billion light years, it is very likely.

Gas composition AND pressure AND temeperature must be exactly right.
The gas composition on Mount Everest is perfect - but you can't breathe it because the partial pressure isn't right for your lungs to work (for any serious length of time). And to get the composition you really need a biosphere that produces this composition...which in turn is a function of the pH value that the ur-cell was floating around at (which is something we still carry around in our cells).

So: get a different pH value in the ur-ocean you get a different balance of respiration of cells...which gives you a different atmospheric composition.

I think that we'll not see that to such a perfectly adjusted level (without even looking at other issues like radiation, posions, etc. etc. that can make a planet 'not nice'). WE adjusted to this level. We didn't to the level elsewhere.

May 11, 2016
Stepping back a bit, it's becoming clear that there are a LOT of planets out there. And this new technique will let us find good candidates to do more detailed observations of. Great news!

May 13, 2016
"This gives us hope that somewhere out there, around a star much like ours, we can eventually discover another Earth."

What does that even mean?


Depends on your interest.

Here it is the hope that Earth analogs (Earth massed planets in the sHZ of a Sun massed star) is amenable for life and especially for an easily detected oxygen atmosphere indicating it, by continuity from our own biosphere. That was the original target for Kepler,. to find some of those. The mission was cut too short though, 3.5 years are unlikely to see 3 orbits of a candidate.

The new filter may have changed that. But still no analog...

May 13, 2016
discover another Earth."
What does that even mean?

Depends on your interest.

That's sort of the point. It's a populist statement that can mean any number of things to different people.

- Something of almost the same size?
- Something rocky in the 'Goldilocks' zone*?
- Something with a biosphere?
- Something that humans can live on unaided?

Those are all rather radically different categories (in order of decreasing likelyhood from "absolutely sure" to "not in a billion universes")

*Goldilocks zone itself being a complete BS concept, BTW. A planet being/not being in the Goldilocks zone says nothing either way about the possibility (or probability) of life on it..

May 13, 2016
It would have been nice if the Kepler probe had lasted longer, but we have more than enough information to push ahead. The good news is we have the upcoming TESS and James Webb Space Telescope (JWST) missions to pair with each other and this will be a powerful combination. TESS will find transiting planets around nearby stars and James Webb will try to characterize their atmospheres, etc.

After TESS/JWST, WFIRST, various ESA missions and three new giant ground telescopes, it seems likely we will finally get serious about direct imaging of all nearby exoplanets, transiting or not. At some point we are going to push to know exactly what is in the Alpha Centauri system, not just Earth-sized, but down to moon-sized. If we knew every exoplanet within say 16 light years, it is a good bet we would know our first target for an interstellar probe, even though we are nowhere near ready to send one. That knowledge will give our collective sense of perspective a much needed boost.

May 15, 2016
discover another Earth."
What does that even mean?

Depends on your interest.

That's sort of the point. It's a populist statement that can mean any number of things to different people


It can be a populist statement, but also signal a specific use here, as I described.

Maybe we will have to agree to disagree.

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