The Nearest Earth

Well, it’s 24 trillion miles away, but at least we now have somewhere to go once Clintrump send us on a spiral of doom:

In this golden age of exoplanetary science the announcement of a planet 30% more massive than the Earth, in an 11.2 day orbit around a low-mass star with a luminosity 0.15% of the Sun’s would usually elicit little more than a raised eyebrow.

Except for the fact that this world orbits the nearest star to ours; Proxima Centauri.

It means that at a cosmically trifling 24 trillion miles (4.243 light years) from where you are at this instant is an alien system with a planet that could conceivably harbor life as we know it. That planet is estimated to be around 4.9 billion years old, it receives about 65% of the Earth’s stellar irradiation, and its skies – whatever else is in them – are bathed in the red-hued rays of a diminutive star only 12% the mass of our Sun.
Say hello to the closest truly alien world.

The planet was discovered by the very small doppler shift its orbit induces in Proxima Cen. Way back in 1993, I did a presentation in my astrophysics class in which I claimed that this was the best approach to finding extrasolar planets. My professor — who was and is a good friend and a brilliant man — thought I was crazy, that we would never be able to measure doppler shift precisely enough to find Earth-like planets. So every time we do find one this way, I still feel a little thrill of vindication.

There are actually plans to send a probe to a nearby world. Russian entrepreneur Yuri Milner is funding a program to send a tiny probe at a significant fraction of the speed of light to a nearby star. It would be a very quick visit. But talking with my exoplanet colleagues this summer, it sounds like he’s serious and this could be done. The main hurdle to be overcome is how to pack it with enough power to transmit a signal back to Earth.

The more we look at the universe, the more ubiquitous we find planets to be. So I’m not entirely surprised by this. The universe is teeming with planets and the number of potentially habitable planets almost certainly numbers in the billions. If we live long enough, we will see a space telescope get a spectrum of a nearby planet’s atmosphere. And then it’s only a matter of time until we find a signal of life in another star system.

In the meantime, let’s hope we one day get off our butts and get moving. The universe is at our doorstep.

2 comments:

  1. Santino

    The planet was discovered by the very small doppler shift its orbit induces in Proxima Cen. Way back in 1993, I did a presentation in my astrophysics class in which I claimed that this was the best approach to finding extrasolar planets.

    I can only imagine the number of chicks you picked up with using that line. :)

    Seriously though, the sheer brilliance boggles the mind.

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  2. Hal_10000 *

    My argument was less about technical feasibility than about practicality. It would take decades to detect something with a Jupiter-like 12 year orbital period.  Our best chance was planets close in with short orbits that you could measure in a few years. Those planets wouldn’t cause much of a wobble in the star, but would cause a stronger doppler shift.  And, in fact, that was the method by which the first exoplanets were detected.

    Where I whiffed was eclipses.  It turned out that looking at millions of stars to find the small fraction where the planet lines up perfectly to eclipse the star by a tiny tiny amount was the best approach.

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