Littlest wanderer

January 10, 2011 9:13 PM

Meet Kepler-10b. The smallest exoplanet ever discovered.

"This planet is unequivocally rocky, with a surface you could stand on", according to NASA. Phil Plait went further, "I’ve seen a lot of reports already calling the planet "solid", but I think it’s clear that it must actually be molten." Just 1.4 times the diameter of Earth, Kepler-10b is 4.6 times more massive than our home.

posted by IvoShandor (36 comments total)

I, for one, welcome our teeny, tiny, iron-rich ... Well, they're, like, rilly far away, so, whatever.
posted by Cool Papa Bell at 9:17 PM on January 10, 2011

Wow. So we're detecting approximately Earth-sized planets now? Are there extenuating circumstances which made this particular detection possible or are we just that badass now? Shit's 'bout to get crazy, yo.
posted by cmoj at 9:23 PM on January 10, 2011

I love that after all these decades the synth slow filter-sweep is still the sound of space documentaries.

In the future, everyone will be Vangelis for 15 minutes.
posted by sourwookie at 9:34 PM on January 10, 2011 [21 favorites]

Wow. So we're detecting approximately Earth-sized planets now? Are there extenuating circumstances which made this particular detection possible or are we just that badass now?

We're just that badass now. "The Kepler Mission, NASA Discovery mission #10, is specifically designed to survey a portion of our region of the Milky Way galaxy to discover dozens of Earth-size planets in or near the habitable zone and determine how many of the billions of stars in our galaxy have such planets."
posted by IvoShandor at 9:36 PM on January 10, 2011

Man, my college education is so useless, now. When I was going to school, there were no exoplanets, and Saturn had about sixteen moons.
posted by Gilbert at 9:45 PM on January 10, 2011 [1 favorite]

cmoj: Alas, there are extenuating circumstances; we're not quite that badass yet. Kepler is looking for transits, that is, it can only detect planets whose orbits are aligned edge-on to us so that they pass in front of the disc of the star and produce a brief dimming of the star.
posted by hattifattener at 9:48 PM on January 10, 2011

We really are just that badass now.

Expect Kepler to come out with more amazing exoplanets as time goes on -- in order to be sure you've seen a planet, it has to go across in front of the the surface of the star 3 times. Why 3? Because you need the time between the points to be the same

Transit. ---------time 1--------- Transit. --------time 2----------Transit.


If time 1 = time 2, you have an orbiting body.

If you were far away looking for our Earth like this, time 1 = time 2 = 2 years, which is the bare minimum time you'd need to find us. Most likely you started partway through a year before your first transit, so it could be up to 3 years.

3 years. That's the magic number.

Kepler launched in early 09, so if we are going to find an Earth-size rocky planet in the habitable zone of a star, we'll start getting that info in *maybe* as soon as the summer of 2012 (I'd expect at least one by early 2013), and we'll still be finding Earth-size planets further out in the habitable zones of stars in the 2013-2016 range.

The badassery has only begun with Kepler. If all goes well, in the next couple years we won't just find a small exoplanet kinda like Earth but all molten, but a proper Earth-size planet in an orbit where there can be liquid water.
posted by chimaera at 9:59 PM on January 10, 2011 [20 favorites]

we might actually start to see habitable planets a bit sooner than that...smaller stars/closer orbits/smaller 'goldilocks zone'/shorter time between transits...
posted by sexyrobot at 10:18 PM on January 10, 2011

Yeah, baby!

What we need now is something to analyze the atmospheres of these exoplanets - and this is just the calm before the deluge. There are ~100 exoplanets waiting in the wings here, and there will surely be more with each new reporting period.

Here's the thing I've been considering - if you really cruise the Kepler mission website, it's extremely emphatic that they will never ever turn that observatory to observe another patch of sky - but who knows how long the spacecraft will continue to function? At some point, there are going to be a clearly be diminishing returns in continuing to survey the very same set of stars - and clearly a huge gain to be had in simply picking a different bit of sky and starting over. When is it OK to actually ask the question "when are you going to repoint Kepler?"
posted by newdaddy at 10:37 PM on January 10, 2011

(that above should be time1 + time2 = 2 years)
posted by chimaera at 10:41 PM on January 10, 2011

When is it OK to actually ask the question "when are you going to repoint Kepler?"

1. The thing about using the transit method, as I explained above you need 3 transits defining 2 orbits to pin down a planet. Ideally you want more to rule out false positives. This is why Kepler's released planets so far have orbital period measured in days and not years. So how long is long enough to find planets? What if you wanted to find the Jupiter-like planet around another Sun? A Jovian year is about 12 years. A Martian year is just over 2 years. The habitable zone around much larger stars start having long orbital periods.

2. One of Kepler's ultimate goals is statistics. If we get a damn good survey of that small chunk of sky, we will know with a fair bit of confidence how likely it is to find a planet in the habitable zone around any given star. Kepler's keeping an eye on over 100,000 stars. Knowing solid stats on those stars is a huge help to future planet hunters.

3. The Kepler field of view was chosen very carefully -- it actually has a bunch of stars not too far away (along our same orbital arm of the galaxy), but there are also not too many stars that are *too bright* so that we can have nice long exposure times on the stars in the field of view without saturating the detector with one bright star and not being able to see the dimmer ones.

4. IIRC, Kepler has limited consumables (propellant to maintain orientation, to sweep around to download data, and to dump momentum from the reaction wheels). I don't think it'll last much longer than 6-8 years in ideal circumstances.

5. Kepler is in an "Earth-trailing" orbit -- it's following the Earth around the sun. But it's going slower, so each year Kepler is getting further and further away. Near the end of its operational life, it'll be harder and harder to get a good signal (and download all that yummy 90+ megapixels of data), and eventually the data rates and power of the signal would be so low that useful science would be extremely difficult.
posted by chimaera at 10:54 PM on January 10, 2011 [8 favorites]

I don't know that it would ever be sensible to change where Kepler is pointed.

If the goal is simply to detect heaps of planets, then sure, repoint and you will find lots of fast orbiting ones. The problem is, without other data you can't know too much more about them, and you lose data about how common slower orbitting planets are.

If they are going for a survey finding out how many planets, and how long they take to orbit, then it is more sensible to take a long term approach. By pointing at the same place for ages, you make sure you get things like Jupiter (which using the above method could take 33 years) as well as the really quick ones and work out what kind of planets are really out there, rather than enriching for the quick ones. Anyone know the expected probability distribution of orbital periods?
posted by scodger at 10:59 PM on January 10, 2011 [1 favorite]

And also what sexyrobot said -- we'll be finding planets closer to smaller dwarf stars in their habitable zones soon enough. Can't say for sure, but 2011 could be the year we find a habitable zone planet around a dwarf.
posted by chimaera at 11:00 PM on January 10, 2011

What we need now is something to analyze the atmospheres of these exoplanets
done and done...all you need is spectra from the planet passing in front of a background star (not sure if its home star is too bright) so that it's atmosphere alters the background light source by leaving 'fingerprints' of its various elements in the light itself (also not sure if kepler is sensitive enough to do this) bonus: oxygen=LIFE(!) (the oxygen content of earth's atmosphere is basically impossible without life, as oxygen is incredibly reactive and would very quickly (geologically speaking anyway...~1,000,000 yrs) be absorbed by elements in the soil if it were not being constantly replenished by biological processes (namely photosynthesis))
posted by sexyrobot at 11:02 PM on January 10, 2011

Are they calling it "Plan B" yet?
posted by I love you more when I eat paint chips at 11:45 PM on January 10, 2011

What's more amazing is that this is only the first of about 700 detections they're following up - if even only half of these are confirmed, that's 350 planets per 100,000 stars in the Galaxy. That means that there's at least (350/1e5)*2e11 = 700 million planets in our Galaxy alone.

And since the transit method at best detects only 10% of the closest in planets to their parent star, that's well into the (wait for it) billions of planets that are out there in our patch of the Universe.

Heady stuff.
posted by fishboy at 11:57 PM on January 10, 2011

FUN FACTS ABOUT KEPLER 10b

• Kepler 10b is around six hundred light years from Earth. That means if you took a photo of it today, you wouldn't see it for six hundred years!
• Kepler 10b was discovered by using a method called the transit with a telescope. The Royal Society used to hire people to go out and sketch the transit of Venus with a telescope, but the practice was later suppressed.
• Kepler was named after the famous Anglo-Indian writer Rudyard Kepler. He worked on the hit Disney movie The Jungle Book.
• Kepler 10b is a planet in the constellation Draco, which is probably evil. Slytherin student Draco Malfoy was named after it.
• The ancients taught us that every planet causes a human emotion. Jupiter makes people jovial. Saturn makes people saturnine, or depressed, and Venus causes venereal disease. Scientists say that Kepler 10b is mostly made of iron, so it probably causes irony.

posted by Joe in Australia at 12:06 AM on January 11, 2011 [18 favorites]

For those interested, I would strongly recommend the Exoplanet app. (developer's site). It's free, comes with an excellent, regularly updated database of all the planets discovered thus far, shows where each is in the sky, has neat animations showing each planet's orbital period and transits, etc. Also, it is just really cool to be informed "We have discovered a new planet!" on your iPhone what feels to be every other day.
posted by Bora Horza Gobuchul at 12:43 AM on January 11, 2011 [3 favorites]

newdaddy When is it OK to actually ask the question "when are you going to repoint Kepler?"

Centuries from now. The better short-term question is, when is it OK to launch another one pointing elsewhere?
posted by aeschenkarnos at 12:45 AM on January 11, 2011 [1 favorite]

chimaera: 3 years. That's the magic number.
posted by russm at 1:54 AM on January 11, 2011

I read that as "Kepler 10 lb" and marvelled at how tiny that exoplanet must be.
posted by moonmilk at 2:43 AM on January 11, 2011 [2 favorites]

This exoplanet stuff never ceases to blow my mind. By far one of the coolest things about living in The Future™
posted by delmoi at 2:56 AM on January 11, 2011

What's more amazing is that this is only the first of about 700 detections they're following up - if even only half of these are confirmed, that's 350 planets per 100,000 stars in the Galaxy. That means that there's at least (350/1e5)*2e11 = 700 million planets in our Galaxy alone.

There was an interesting animation of the discovery of asteroids or something, linked here on metafilter. What was cool was that you could see the effect of technology on the discovery. At certain times you would see "Sweeps" of new discoveries. It was very interesting.
posted by delmoi at 3:00 AM on January 11, 2011

Just 1.4 times the diameter of Earth, Kepler-10b is 4.6 times more massive than our home.

Remember, of course, that the volume of a sphere is described by V=4/3πr³. 1.4³=2.744. Of course, between additional compression due to enormous mass, and room for error (1.5³=3.375), it's not particularly surprising. Then again, a lot of people lack an intuitive grasp of mathematics, and that's how they get you in marketing every time.
posted by explosion at 3:55 AM on January 11, 2011 [1 favorite]

Prince not included.
posted by Joe Beese at 5:13 AM on January 11, 2011

"One day the oceans we will cross will be the galaxy itself."

Actually, I'd say were more like a bunch of cave men sitting on some frigid beach wondering where these big nuts full of milk keep coming from.
posted by The 10th Regiment of Foot at 5:40 AM on January 11, 2011 [2 favorites]

Can't say for sure, but 2011 could be the year we find a habitable zone planet around a dwarf.

And we shall cal it Shire.
posted by The Whelk at 5:48 AM on January 11, 2011

Are they taking advance applications for the hiber-ship yet?
posted by T.D. Strange at 7:53 AM on January 11, 2011

Are they taking advance applications for the hiber-ship yet?

Link plz.
posted by thsmchnekllsfascists at 7:56 AM on January 11, 2011

This is timely, as I have just begun to read The Songs of Distant Earth>.
posted by Severian at 8:10 AM on January 11, 2011

moonmilk: I read that as "Kepler 10 lb" and marvelled at how tiny that exoplanet must be.

Same here. Brings to mind Bottomos, the tiny third moon of Mars.
posted by Herodios at 9:06 AM on January 11, 2011 [1 favorite]

All we need to do not is get our asses to Mars, dig up the ancient alien technology that will help us invent FTL travel, and Bob's your uncle.
posted by EndsOfInvention at 9:09 AM on January 11, 2011

"I read that as "Kepler 10 lb" and marvelled at how tiny that exoplanet must be."

Well, to be fair, it's 10 lbs. of dark matter. So it weighs as much as 10 billion lbs. of regular matter (and 10 British billions of lbs. of the new lite matter, which has half the calories).
posted by Eideteker at 9:21 AM on January 11, 2011

It's not the smallest exoplanet ever discovered, that's PSR B1257+12 A
posted by moorooka at 2:00 PM on January 11, 2011 [1 favorite]

When is it OK to actually ask the question "when are you going to repoint Kepler?"

Far better than repointing Kepler would be to build another one and launch it. Indeed, if Kepler is as successful as I think it will be, given the results it is already getting, then it would be far more useful to build 2-3 more of them and get them all going at different parts of the sky, rather than building and launching one new better one.

The research time is a huge part of the costs. Building one probe is hard, building the second copy is buying parts and the cost to loft the satellite (not insignficiant by any means.)
posted by eriko at 3:49 PM on January 11, 2011

It's not the smallest exoplanet ever discovered, that's PSR B1257+12 A

No one ever seems to count pulsar planets, but, yeah, I knew that.
posted by IvoShandor at 8:53 PM on January 11, 2011 [1 favorite]