Could aliens just be four ‘short’ light-years away? That’s the question being thrown around today after the announcement that scientists have discovered a planet orbiting Centauri B, which is a part of our nearest neighboring star/sun system. By far the best run-down on this news is Lee Billing’s article “Alpha Centauri and the New Astronomy“:
[T]oday a European planet-hunting team announced their discovery of an alien world about the same mass as Earth. This alone would be noteworthy, for of all the “exoplanets” now known beyond our solar system, only a very few, and very recently, have been shown to at all resemble our own. But there is more to the story. This particular exoplanet resides in a three-day orbit around the dusky orange star Alpha Centauri B, a member of the Sun’s closest neighboring stellar system. There are two other stars in the system as well, the yellow Sun-like star Alpha Centauri A and the red dwarf star Proxima Centauri.
At a distance of just over 4.3 light years, the stars of Alpha Centauri are only a cosmic stone’s throw away. To reach Alpha Centauri B b, as this new world is called, would require a journey of some 25 trillion miles. For comparison, the next-nearest known exoplanet is a gas giant orbiting the orange star Epsilon Eridani, more than twice as far away. But don’t pack your bags quite yet. With a probable surface temperature well above a thousand degrees Fahrenheit, Alpha Centauri B b is no Goldilocks world. Still, its presence is promising: Planets tend to come in packs, and some theorists had believed no planets at all could form in multi-star systems like Alpha Centauri, which are more common than singleton suns throughout our galaxy. It seems increasingly likely that small planets exist around most if not all stars, near and far alike, and that Alpha Centauri B may possess additional worlds further out in clement, habitable orbits, tantalizingly within reach.
Australians (and other people of low enough latitudes) will know the Centauri star system as the left-hand (eastern) pointer star associated with the Southern Cross constellation. And speaking of constellations, Lee Billings points out the breath-taking fact that in galactic terms, the newly-discovered exoplanet “is so very near our own that its night sky shares most of Earth’s constellations” – excepting the constellation Cassiopeia, which would gain a sixth star, six times brighter than the other five: our own Sun.
Some of the other interesting tweets seen shortly after the announcement:
At 1:93,000,000 scale (1 mile per 1 Astronomical Unit) the Sun-Pluto distance is 40 miles. Alpha Cen would be distance from Earth to Moon.
— Lee Billings (@LeeBillings) October 16, 2012
The fastest spacecraft ever built by human kind (Helios twins) would take just under 18,000 yrs to reach this new exoplanet (give or take)
— Nick Howes (@NickAstronomer) October 16, 2012
Back-of-envelope calculation of stellar flux and orbital period assuming albedo 0.3 says Alpha Cen B b’s surface temp is >1000 Fahrenheit.
— Lee Billings (@LeeBillings) October 16, 2012
The Venusian Tourism Board would like to remind you that there is an Earth-mass planet only 1.1627 AU away.
— Jason Perry (@volcanopele) October 16, 2012
SETI already searched Alpha Centauri for radio signals; will try again in light of planet discovery, SETI master Seth Shostak tells me.
— Brian Vastag (@brianvastag) October 16, 2012
For the academically-inclined, you can download the original scientific paper on the discovery here.