Alien worlds

The blue skinned race of aliens that fought for their survival in the film “Avatar” lived on a moon of the gas giant Polyphemus that orbited α-Centauri A, one of the brightest stars in the southern sky.

Well, in October 2012, using data from the 3.6 m telescope at La Silla, Chile, a Swiss team detected a real planet orbiting the companion star to α-Centauri A, α-Centauri B. It’s a rocky planet, about the size of the earth circling a star about the size of our Sun. And it’s the nearest star system to our planet, only 4.3 light years away!

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The planet, itself, has not yet been seen. Its presence was deduced from the oscillation it imparts to the mother star which can be measured from the Doppler shift in the star’s spectral signature. The radius of the planet’s orbit can then be determined from the period of its orbit and the mass of the star.

And that’s where the trouble starts. Analysis of the data shows that the planet is orbiting so close to the star that it must be blasted with radiation, stripped of any atmosphere and scorched to a cinder.

But there is still hope. In 2009, NASA launched the Kepler telescope into orbit which is now viewing over 150,000 stars in one tiny section of the sky between the constellations of Cygnus and Lyra. Its mission is to find planets, though using a different technique from the La Silla Telescope. Rather than analyzing shifts in the spectral signal of the stars, it’s measuring the dip in light intensity when a planet transits in front. It has now identified nearly 3000 possible planets and shown that over 17% of stars have multiple planet systems. We can therefore be optimistic that there are other planets orbiting α-Centauri B and some of them are likely to be in the “Goldilocks zone” where water can condense and cute beings with tails can live in harmony in the jungle.

And if evil corporations are planning to fly in and exploit the planet, they had better think again, for even if a probe is launched by one of the most powerful rockets on Earth, boosted by a gravitational slingshot around Jupiter, and further accelerated by a radioisotope thruster, it would still take 28,000 years to reach the α-Centauri star system. To quote Douglas Adams, “Space is big. Really big.”

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