(Great video by Tony Darnell)
Script below (with relevant time indication for the hard of hearing)
0:17On December 5th, 2011, the Kepler Science team announced that they had confirmed a planet
0:23roughly the size of ours, in orbit around a star very similar to the Sun.
0:31What’s more, the distance of this planet from its star was perfect. It wasn’t too close,
0:39and it wasn’t too far away.
0:43If this planet were the Earth, life could live there.
0:49It’s called Kepler-22b.
0:53The parent star, Kepler-22 is very similar to our Sun. Classified as a sun-like G-type
1:05star, it is very dim as seen from Earth and measurements of dips in light as the planet
1:10passes in front are very difficult to make.
1:16Nevertheless, the Kepler Space Telescope first noticed this star as having a planet that
1:22is possibly like Earth almost immediately. A mere three days after being declared operationally
1:30ready, Kepler took notice that something was interesting in orbit around this small, dim,
1:37Sun-like star located 600 light years away.
1:44Followup observations on the ground and from the Spitzer Space Telescope confirmed the
1:54Kepler-22b, the first Earth-sized planet found by Kepler in a habitable zone around another
2:01star, has been confirmed. Of the 54 habitable zone planet candidates currently under scrutiny
2:11by the Kepler Space Telescope, this is the first to be confirmed.
2:21Kepler-22b has a radius 2.4 times that of the Earth, putting this planet in a category
2:26commonly called a super-Earth. It takes 290 days to travel once around around its sun,
2:34which is slightly smaller and cooler than ours.
2:38The promise of Kepler-22b, however, is tempered by what we do not know about it. There is
2:46much hidden from us. The most glaring gap in our knowledge is that we don’t know what
2:52it’s made of. It could be a rocky planet like Earth, or it could be gaseous and more like
3:00It may even be covered entirely of water, an ocean planet with an altogether new set
3:10of possibilities for life.
3:14What we do know is that while Kepler-22b is Earth-like, it is hardly our twin. At 2.4
3:23times the radius of the Earth, if it is rocky and very dense, then life could be very hard
3:28here. We also do not know if it even contains an atmosphere.
3:36And if it does have an atmosphere, how much heat does the atmosphere trap? If it traps
3:41too much, then Kepler-22b could be more like Venus, a planet known to be very inhospitable
3:51If it’s a Neptune-like planet, made entirely of gas, then the chances for life, at least
3:57as we know it to be, are impossible. Living here, any life would take on a completely
4:06The chances for finding out the answers to many of these questions about Kepler-22b,
4:10while possible, are somewhat remote with our current levels of technology. For example,
4:17using radial velocity measurements, a spectral technique that allows us to find out chemical
4:22compositions of stars, planets and their atmospheres, in addition to the planet itself by measuring
4:27the wobble of the star as the planet circles it, is not feasible for a star so far away
4:33with such a small planet in orbit around it.
4:45Perhaps the biggest promise offered by the confirmation of Kepler-22b isn’t the planet
4:50itself, but lies in the fact that it was found so soon after we started looking for planets
4:55like the Earth.
4:58With Kepler, the number of Earth-sized candidate planets has increased 200 percent, and the
5:07number of super-Earth candidates has increased 140 percent since February 2011. This bodes
5:13very well indeed for our future search for life in the galaxy.
5:23The discovery of Kepler-22b as an Earth-like planet in a habitable zone is encouraging,
5:28but that by itself offers limited hope in our search for life elsewhere in our galaxy.
5:33So far, all we know is that Kepler-22b is a smallish planet in orbit around a star like
5:40our Sun at a distance that is very promising.
5:44It made be rocky, like the Earth, or it may be gaseous, like Neptune, but for us to know
5:53the true promise of Kepler-22b, we need to keep looking. Keep collecting information
6:00with as many instruments as we can bring to bear.
6:04Because it’s what we DON’T know about Kepler-22b that offers us the most promise.