This is huge. Massive. The paper goes on to say that further studies may confirm if Proxima b’s atmosphere contains chemicals that can indicate the presence of biological life, such as methane.
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“The discovery of the potentially habitable planet around Proxima Cen is the culmination of 30 years of work that has improved stellar velocity measurement precision from 300 m/s (metres per second) to 1 m/s”, said one of the researchers, Paul Butler from Carnegie Institution for Science in Washington.
There are still many questions, especially the crucial one of whether the planet has an atmosphere.
If there are planets around either or both of the Alpha Centauri stars, Proxima Centauri is still so distant and dim that it would be just another star in their night skies and much less obvious than our own Sun.
Its star, Proxima Centauri, is much fainter than the sun and just 0.12 times its mass (1.4 times the mass of Jupiter), and the planet huddles nearby, at just 5 percent the distance between the sun and the Earth. Using conventional space technology (either manned or unmanned) and some clever slingshot manoeuvres, it would take at least 15,000 years to reach Proxima Centauri. That doesn’t rule out life, but it means that any that has evolved will have learned to cope with the hostile conditions. We don’t know if the planet has an atmosphere at all, let alone what it might be made of. Combined with the fact that we’ve managed to live through half a dozen major mass extinctions, and the odds of life evolving quickly and early on any given planet start to look pretty good.
With thousands of exoplanets discovered to date, it’s no wonder that we regularly come across “Earth-like worlds” around distant stars.
The nearest habitable world beyond our Solar System might be right on our doorstep – astronomically speaking.
It may be that Earth truly is special. If a small, unmanned spacecraft were launched in the next few years, it could reach Proxima b by 2100; children living in 2016 would be alive to see the craft’s arrival. It is only slightly larger than our planet and likely has a rocky surface.
Even so, it’s a ideal target for our first interstellar missions.
These would travel at perhaps 20% of the speed of light, shortening the journey to a star like Proxima Centauri to mere decades. It seemed from where we were sitting to be near-identical to Earth, and have conditions – potentially – ripe for life.
One thought experiment, known as the Drake equation, tries to estimate the number of other civilizations that might exist in our galaxy. That, of course, makes life more and more likely. If that’s the case, then we would expect to have already found some aliens.
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The famous counter to the Drake equation is the Fermi paradox. “We’ll have to look at it more to see if we can actually detect water”. The Cold War, for example, could have very easily wiped out just about all life on Earth – and nuclear proliferation and global political instability may still end us all. What we know about Kepler-452b, for example, is inferred from the weak shadow observed when it passes its star.
