Unbelievable. A few days ago we were up to 525 known extrasolar planets according to the Extrasolar Planets Encyclopedia. Nine of them were discovered using the planet-finding Kepler spacecraft. Then on Tuesday NASA scientists announced an additional 1,226 Kepler discoveries for a grand total of 1,751.
How big a number is that? Go out to a rural setting the next clear night and look up at the stars. Now picture nearly every single star you see as a planet – that’s how many planets there are!
The results are based on observations made by the telescope between May and September 2009. Kepler’s unwavering eye stared at 156,000 stars within 2000 light years of Earth, looking for tiny, telltale dips in their brightness caused when a planet or planets transits their host star.
The telescope stared simultaneously at every one of those stars, measuring the brightness of each every 30 minutes. Sifting through the mound of data revealed the signatures of a host of new planet candidates, many of which will have to be confirmed through further observation. Analysis of the amplitude and timing of the dips in the stars’ light will help astronomers determine the planets’ orbits, sizes and masses. So much from such a thin trickle of data.
Here’s the amazing part. Among the new worlds, Kepler found at least 54 that lie within their stars’ habitable zones, where temperatures are moderate enough for liquid water and potentially life to exist. And that after exploring only 1/400 of the sky!
“The fact that we’ve found so many planet candidates in such a tiny fraction of the sky suggests there are countless planets orbiting sun-like stars in our galaxy,” said William Borucki of NASA’s Ames Research Center, the mission’s science principal investigator.
If you extrapolate Kepler’s bounty across the entire sky, the tally would come to some 20,000 planets within 3,000 light years of Earth where life might be possible.
Now for the breakdown: 288 are “super Earths”(planets a couple times larger than Earth and considerably denser but nowhere near the size of the Jupiter-sized worlds common among exoplanet discoveries); 662 Neptune-sized; 165 the size of Jupiter and 19 larger than Jupiter. Of the 54 worlds in the “habitable zone”, 49 are super Earths and five are similar in size to our own planet.
One of the coolest is a system of six planets, ranging in size from super Earths to Neptune, revolving around the star Kepler-11 2,000 light years away. It’s the tightest-packed solar system known. The planet Kepler-G revolves at Venus’ distance from its parent star, while the other five have orbits smaller than Mercury’s.Â Just like our solar system, they all orbit within the same flat plane, but because they’re so close to their star, the intense heat they receive makes the possibility of life unlikely.
Ever hear of the song Planet Claire by the B-52’s? You know, the place where the air is pink, trees are red and nobody has a head. Given all the new discoveries, I’d like to nominate Claire as a potential future name when the International Astronomical Union (IAU) naming committee decides on official names for so many of these new worlds. We’ve run through all the various Greek and Roman deities, so let’s start using more of the name people give other people, including Claire.
Before signing off today, I wanted to make you aware of an opportunity to see a very young lunar crescent this evening in the southwestern sky some 20 to 30 minutes after sunset tonight. You’ll need excellent skies without haze or cloud and a good horizon view.
The moon will only be a few degrees high for Midwest viewers and a little better placed for those living farther west in the mountain states and the West Coast where the moon at sunset will be 22 and 23 hours old respectively. We don’t get many chances to spot a moon less than a day old. Go for it if you can.