Kepler-62 Has 2 Good Candidate Planets In the Search for Life 79
astroengine writes "About 1,200 light-years from Earth, five planets are circling around sun-like star Kepler-62, two of which are fortuitously positioned for water, if any exists, to remain liquid on their surfaces — a condition believed to be necessary for life. The discovery, made by scientists using NASA's planet-hunting Kepler space telescope, is the strongest evidence yet for more than one Earth-sized planet existing in a star's so-called 'habitable' zone. 'We're particularly delighted to find that there are two planets in the habitable zone,' lead Kepler scientist William Borucki, with NASA's Ames Research Center in California, told Discovery News. 'It sort of doubles our chances of finding that Earth we'd all like to find. When you think about Earth and Mars, if Mars had been a bit larger, if Jupiter hadn't been so close, we'd again have two planets in the habitable zone and maybe we'd have a place to go,' he said." There's also a third planet believed to be a good candidate for hosting water.
Re:power level of a detectable signal at 1200 ly ? (Score:5, Interesting)
Interesting question. I'll try: we're just barely able to detect the signal from Voyager 1, which is currently about 18.4 billion km, or 0.0019 light-year away. I couldn't find the exact emission power from the antenna, but the Wikipedia page mentions that the electric generator has around 250W of power. Let's say 200W of that go in the antenna. Translating this to 1200 ly, using the 1/r^2 rule, gives about 76 TW.
That's a lot, about 5 times the total average energy consumption of the World, but not out of the realm of possibilities. So if there was an advanced civilization with a lot of energy and a very big, very directive antenna that desperately wanted to talk to us, we might just be able to pick it up.
Re:power level of a detectable signal at 1200 ly ? (Score:5, Interesting)
Or, they could use a star itself and modulate the light coming from it, like stellar semaphore.
One method that has been proposed http://www.iterate.com.au/SETI/SETI.htm [iterate.com.au] uses a swarm of self-replicating robots. Given raw materials to work with it could in time create a large enough structure or cloud in front of the star so as to be able to send a signal to a large percentage of the heavens. This would be detectable over much greater distances than 1200 ly.