"A time will come when men will stretch out their eyes. They should see planets like our Earth." – Christopher Wren.
IT'S CALLED Gliese 581g, and is one of the six identified planets that orbit dim red dwarf star, Gliese 581, in the constellation of Libra. In astronomical terms, it is a close neighbour, our 86th closest star and a mere 20 light years away (a Nama-like 200,000,000,000,000 kilometres). But Gliese 581g has a remarkable and so far unique potential that may still make it worth the trip: according to the Astrophysical Journalthis week there is a very strong likelihood it contains water, could/does sustain life, and is even habitable by man.
We could get there in 220 years, says Steven Vogt optimistically, “if we start now”. Vogt, of the University of California, Santa Cruz, and Paul Butler of the Carnegie Institution in Washington, led the team that made the discovery after an 11-year search using telescopes in Chile and Hawaii to observe the tiny tell-tale gravitational wobbles the star makes as its planets swing by.
Gliese 581g is bang in the middle of what is known as the “Goldilocks zone”, an orbit where the heat from its star is neither too cold nor too hot for water to exist in liquid form on its surface. “This is our first Goldilocks planet – just the right size and the right distance from its sun,” Butler says. “A threshold has been crossed.” Much more study, however, will be needed to identify the presence of water, let alone life forms.
Unlike Earth it does not spin on its axis and so one side is sunny and the other freezing, with temperatures averaging a somewhat Antarctic –31 to –12 degrees. But, in between, is a temperate zone whose climate would be comfortable to Earthlings, with wind gusts that don’t seem to exceed a blustery 40 miles an hour. It is just bigger than Earth but with three times our mass, and so a visitor would feel a bit heavier but have no trouble walking upright. “Our findings offer a very compelling case for a potentially habitable planet,” Vogt says.
Some 500 unpromising planets have to date been identified beyond the solar system, “exoplanets”, a drop in the ocean in a universe containing about one septillion (one with 24 zeros) stars. But the relative ease with which Gliese 581g has been identified as potentially life-sustaining suggests many more will follow in what Vogt calls “a second Age of Discovery”.
Over to you, St Brendan.