The dwarf star Trappist-1 is 39 light years from us – a stone’s throw by cosmic standards.
It’s orbited by seven newly discovered Earth-sized planets. Even the outermost of these is six times closer to its sun than Mercury, the closest planet to our own. Were these planets as close to our sun as they are to Trappist-1, they would all have been swallowed up long ago.
Their orbits are so tight that the time they take to do a circuit of their sun varies from 1.5 days to 20 days. Those are some seriously short years compared to ours!
Even Mercury takes 88 days to complete her orbit – the quickest in our system.
Their speedy orbits imply that most, if not all, probably don’t rotate on their axes. One side would permanently face their sun. This phenomenon is known as “tidally locked.”
Trappist-1 is an ultra-cool dwarf star only a little bit larger than Jupiter, and is 2000 times less bright than our sun. This explains how temperate life would be possible on one or more of its seven planets, despite them being so close to their star.
The star system is named for the Trappist robotic telescope in the Atacama Desert of Chile which first detected them.
Trappist-1 burns its hydrogen supply so slowly that it could last for ten trillion years – which is 700 times the age of the known universe. That’s what I call extreme energy efficiency! By the time our sun expires in three billion years or so it will still be a cosmic infant.
Astronomers are pretty excited about this discovery as these planets have the right conditions for liquid surface water and possibly life as we know it might abound on or more of them.
The fifth planet in the system is considered the most habitable. From there, Trappist-1 would appear salmon-pink and 10 times bigger than the sun in our skies. The neighbouring planets, depending on the position of their orbits at the time, would appear up to twice the size of our Moon.
“It would be a beautiful show,” declared Amaury Triaud from the Institute of Astronomy at Cambridge University.
After the planets were discovered, NASAs Spitzer space telescope observed the star for 21 days, working with other observatories to gather data about their size and orbits.
The next step is to ascertain whether they have atmospheres which could sustain life. The mere presence of water and methane, discovered by the Hubble Telescope, doesn’t indicate the presence of life.
Space science is advancing in leaps and bounds. The first in a new wave of state of the art telescopes, the James Webb Space Telescope, goes into action next year with the ground-based Giant Magellan Telescope following in 2023.
So by the end of the next decade we may be pretty close to finding out whether some of our cosmic neighbours have what we rather presumptuously call intelligent life. Perhaps some merely have bacteria and microbes while others may well have life forms which would make us look positively primitive.
The cool stars known as M-dwarfs, of which Trappist is one, outnumber “sun-like” stars 12 to 1, and research thus far indicates that about one in four of these have earth-sized planets in orbit.
Some of these dwarf stars have a tendency to produce sudden fierce bursts of x-rays and ultraviolet light, which wouldn’t be ideal for any life in proximity to them. But life, maybe “not as we know it” may have evolved to survive under conditions vastly different to those on Earth. We can’t assume that Nature used the same building blocks everywhere.
Over 3400 planets have already been discovered in the galaxy but none of them so far are similar enough to Earth to be considered a “twin.”
Exciting times lie ahead for space science. Ignas Snellen, an astrophysicist from the Leiden Observatory in the Netherlands, stated: “This is really something new. When they started this search several years ago, I really thought it was a waste of time. I was very, very wrong.”
It remains to be seen whether a breakthrough in faster-than-light space travel will ever become a reality. If it does, this would be the most game changing event in history.