To hell with our Solar System, with its measly four rocky planets. TRAPPIST-1 40 light-years away has seven, at least three of which might be habitable. Understandably, the discovery of these planets made headline news this past week.
But what might life be like in this system? Well, it might be quite different to here, if it's able to survive the star's intense bursts of radiation. So far, we know very little about the system other than the type of star (an ultra cool red dwarf) and the mass, radius, and orbits of most of the planets. It's enough to make some educated guesses, though.
If there is life there, the views from the surface of the planets might be rather glorious. Above the same point on each planet – as all are tidally locked – the star would appear a salmon-pink color. But as the planets orbit so close to each other, they would also sweep through each other’s skies, sometimes appearing as large as the Moon does in Earth’s sky.
From our planet, we can make out craters, mountains, and more on the surface of the Moon with our naked eyes alone, but we need to send spacecraft on multi-year missions to get a close-up view of other worlds in our Solar System. If an advanced civilization is lucky enough to live on one of the TRAPPIST-1 planets, then they could study their other worlds – some of which might also be habitable – from their own backyards.
From left to right, TRAPPIST-1b, c, d, e, f, g, and h. NASA/JPL-Caltech
Three of the planets in the system – TRAPPIST-1e, f, and g – may have the necessary conditions for water. They’re located in the habitable zone of the star, where temperatures are just right for liquid water, and thus maybe life.
The major unknown at the moment is what sort of atmospheres these planets have to protect against UV radiation from their star. TRAPPIST-1, being 200 times dimmer and 10 times smaller than our Sun, is a type of star that unleashes powerful flares of energy. The planets in the system orbit extremely closely, each no more than a few days, so they are susceptible to these bursts of energy.
“The main barrier to life in a system like this compared to Earth is potentially UV radiation,” Jack O'Malley-James from the Carl Sagan Institute at Cornell University in New York told IFLScience. “It becomes potentially a limiting factor for what life can and can’t do on the surface of the planet.”
An artist's impression of the surface of TRAPPIST-1d. NASA