Monday, August 29, 2016

That planet around Proxima Centauri




There is news from space!

And it's big.

Real big.

As Phil Plait reports at Bad Astronomy, an exoplanet has been found orbiting Proxima Centauri, the star nearest our Sun. What's more, it is within what is known as "the habitable zone," that sweet spot a planet must occupy in order to support life (as we understand it.)

The planet, being called Proxima b for now, is about 1.3 times the size of Earth and orbits Proxima at a range closer than the Earth does around the Sun. Actually, a lot closer. This still places Proxima b in the habitable zone because Proxima is a faint red dwarf star, about 0.14 times the diameter of the Sun. This means that the newly found exoplanet receives only two-thirds the light and the heat that Earth does from the Sun. This also means that there is a distinct chance that b may have liquid water on its surface. We're going to have to wait for more data on that as starlight will be analyzed as it goes through b's atmosphere. 

Adding to all of the excitement is of course the planet's proximity to Earth. At about four light years away, that's practically next door in astronomical terms. And it might be habitable. Naturally, I've even seen a few in my social media circles who have taken to heralding this news as "another step closer to disclosure." Not so fast. Plait is also quick to advise caution at the link. While this newly discovered planet is Earth-sized there is yet no way of telling if it is Earth-like. We as yet have no idea of the composition of this planet, but given its near orbit to its star, the law of averages might suggest that it is a terrestrial planet, meaning it's made of rock and metal like our Earth.

Also, if extraterrestrial life is on your mind, you might ask yourself why we've never detected signals from this planet given our proximity to it. I know, I know, there are could be many reasons and absence of evidence is not evidence of absence. Still, it makes one wonder. Doesn't matter. This remains a significant find, among the mirabilia of recent scientific discovery and astronomers will be poring over it for years to come.

By the way, check out Phil Plait's explanation of the Centauri star system. I always knew it was a binary system, Alpha and Proxima, but is in reality a trinary system. So cool. Really, go to the link as Phil does a far better job of describing it with more perspicuity and accuracy than I ever could.


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