Kepler-186f: Most 'Earth-Like' Alien World Discovered 239
astroengine (1577233) writes "About 500 light-years away in the constellation Cygnus lives a star, which, though smaller and redder than the sun, has a planet that may look awfully familiar. With a diameter just 10 percent bigger than Earth's, the newly found world is the first of its size found basking in the benign temperature region around a parent star where water, if it exists, could pool in liquid form (abstract). Scientists on the hunt for Earth's twin are focused on worlds that could support liquid surface water, which may be necessary to brew the chemistry of life. "Kepler-186f is significant because it is the first exoplanet that is the same temperature and the same size (well, ALMOST!) as the Earth," David Charbonneau, with the Harvard-Smithsonian Center for Astrophysics, wrote in an email to Discovery News. "Previously, the exoplanet most like Earth was Kepler-62f, but Kepler-186f is significantly smaller. Now we can point to a star and say, 'There lies an Earth-like planet.'""
Re:Better leave now (Score:5, Informative)
Re:Great, now all we need to do... (Score:5, Informative)
An engineering problem in the sense that there is not enough matter in the universe to accelerate a spacecraft at 1 g for 2 years using any currently plausible propulsion method.
Re:They already know about Earth (Score:5, Informative)
have known at the minimum that Earth has liquid water, oxygen, and chlorophyll
Chlorophyll doesn't need to be detected - the presence of elemental oxygen alone is evidence of life, as it is too reactive to remain elemental unless some reaction is replenishing it, and as far as we know the only such reactions are biological in nature.
Re:Better leave now (Score:4, Informative)
I suspect things work a bit more linearly than you might surmise. Maybe I just read your post wrong, but let me re-word it to see if I got it right, with a few changes:
Right now, we (as a human civilization) have pumped out radio signals that currently are racing out past the 100+ light year mark. This is stuff we sent long ago (e.g. Titanic's SOS call has reached the 102-light-year-mark, other early Marconi radio broadcasts in Morse code, stuff like that.)
The initial contact is the bitch - you send something out to a planet 50 ly away, hope someone is there and is capable of listening at that moment, along the frequency band you sent, has his antenna pointed at the same vector from which your signal is originating, has sufficient technology and skill to discern it as a intelligent/sentient message created intentionally. Oh, and you'd better hope something in-between doesn't obliterate the signal on its way there, and that it was powerful enough to not be diffused too much.
Meanwhile, your alien recipient not only has to receive it, but he needs to be capable of sending something in return. If he can decode what you sent and then send a suitable reply - bonus! If he sends something with the same pattern back, okay.
Now we get to wait another 50 years before the reply gets back here, we still have to be around as a civilization (with the right equipment!) to hear it, have someone interested in listening for it (what, 100 years after his grandpappy sent the original signal?), and again, hope the alien dude didn't decide that maybe a different and random (to you) frequency band would have been better to send the reply with... and toss in the same hazards experienced when sending the original request signal.
(...and you thought postal service was slow...)
Re:Better leave now (Score:4, Informative)
Sorry, but time is not an absolute clock that ticks the same everywhere. Time is a local phenomenon, and only a local phenomenon. We all live in separate time frames.
If you accelerate to 99% of the speed of light, the Lorenz factor is a little over 7, which means that for an outside observer counting one year on the clock, you will only have experienced 51 days.
As your speed creeps closer and closer to c, the time dilation increases. If you could reach 99.999% of c, the Lorenz factor would be 223. For an outside observer watching you travel 100 light years from A to B, 100 years would pass. But for you, less than 5.5 months would have passed.
If you could maintain a 1g acceleration indefinitely, you could travel to another galaxy and back within a human lifetime. It's not feasible, though, as you require more and more energy to accelerate the faster you go, and as you approach c, you approach needing an infinite amount of energy for an infinitesimally small boost in speed.