Yesterday, in arguably what is the most important exoplanet discovery ever made, scientists from the Pale Red Dot project announced they had found a potentially Earth-like world on the closest star to our Sun, Proxima Centauri – a stone's throw away in astronomical terms.
The discovery of the planet, named Proxima b, has understandably sent the scientific world into raptures, with many commenting on how this world is close enough to study in detail, and perhaps even visit.
But what do we know about this world so far, could there be life there, and can we actually visit it? Let’s take a look at some of the biggest questions about Proxima b.
Does it definitely exist?
No, but it’s very likely. The planet was found by measuring wobbles in its parent star caused by the planet’s orbit, known as Doppler spectroscopy. While the scientists behind the discovery are almost certain the planet exists, there’s a small chance it doesn’t. Consider Alpha Centauri Bb, a proposed exoplanet around the nearby Alpha Centauri B star. This was later thought to be a mistaken discovery. However, this time around, the scientists say they have been more thorough. So, Proxima b probably exists.
Is it habitable?
We don’t know for sure yet. All we know about the planet so far is that it has at least 1.3 times the mass of Earth (and at most about 3 times), it is probably rocky, and it orbits its star at a distance 5 percent that of the Earth-Sun distance. Around a star like our own, such a world would be uninhabitable.
But Proxima b’s parent star is a much smaller star, a red dwarf, which means it emits less light than our Sun, so a habitable planet can exist closer in. Indeed, Proxima b is thought to be in the habitable zone of its star, where liquid water could exist. Such a star is prone to bursts of X-rays, though, which may complicate matters.