Scientists have long thought that Earth-sized planets were abundant, but the new research shows just how many of them there might be.
Many of those planets might never be seen, because they don’t pass in front of their host star and so aren’t visible.
TRAPPIST-1 “burns hydrogen so slowly that it will live for another 10 trillion years – more than 700 times longer than the Universe has existed so far, which is arguably enough time for life to evolve”, wrote Ignas AG Snellen from the Leiden Observatory, in an accompanying article about the discovery.
All of the planets were found using a method called “transit photometry”.
That’s because roughly the same amount of energy would be coming from the star as warms our Earth – but it does so infrared.
Because the star is so dim in relative terms, all of the planets are warmed enough to sit in the temperate zone.
This chart shows, on the top row, artist conceptions of the seven planets of TRAPPIST-1 with their orbital periods, distances from their star, radii and masses as compared to those of Earth.
The bottom row shows data about Mercury, Venus, Earth and Mars (NASA/ It’s unlikely that any possible life that is on the planet would actually see this way, the scientists noted, since they would probably have evolved entirely different eyes – or perhaps none at all.
"This is the first mission into the real outer Solar System, the real Wild West, the Kuiper Belt," said Alan Stern, New Horizon’s principal investigator "We haven’t done a first reconnaissance mission of a new planet since 1989, 26 years ago, and nothing like it is in the books to ever happen again.That might mean that the new system is actually not all that out of the ordinary.Scientists expect that for each planet we find, there are as many as 100 we can’t see – and so the scientists might not actually have been lucky, but rather seen something that wasn’t that unusual.About a fifth of the sun-like stars are thought to have Earth-sized planets close enough to them to support life.
In all, there might be 40 billion potentially habitable words sitting just in our galaxy, the Milky Way, astronomers estimate.
That’s despite the fact that they are all so close to it – each of them sitting nearer to the star than Mercury, the planet in our solar system that orbits closest to the Sun.