This afternoon, an international team of scientists announced the discovery of not one, not two, but seven roughly Earth-sized exoplanets closely orbiting a dwarf star called Trappist-1. The discovery of this pocket-sized solar system vastly accelerates the quest for life outside our own, the researchers said during a NASA press conference.
Three of the planets—called Trappist-1d, e, and f—are in the star’s “habitable zone,” meaning their temperatures are in the right range to potentially harbor liquid water on their surfaces. “Having three of these planets in this habitable zone is very promising for the search for life,” said Michaël Gillon, the lead author of the relevant study, upcoming in the journal Nature. Early measurements have also indicated that two of the planets, at least, are rocky (like Earth) rather than gassy (like Neptune).
Compared to the star that Earth orbits around, Trappist-1 is tiny—if our sun were a basketball, Trappist-1 would be a golf ball. But it has its planets in a much tighter orbit—it takes the closest planet, Trappist-1b, a mere 1.5 days to go around the star, while the furthest, Trappist-1h, takes about 20 days. This closeness makes up for the star’s coolness, and creates possible conditions for organic life.
But before we start sky-fishing for aliens, there are still a number of items to check off the life list. Researchers are particularly interested in the chemical compositions of the planets’ atmospheres. The presence of oxygen would indicate the possibility of life, while a particular cocktail of oxygen, carbon dioxide, and methane would make it almost certain.
Even if these three planets turn out to be dead as doornails, the implications of their discovery are still massive, researchers say. In the past, we’ve assumed that Earth-like planets could only be found around sun-like stars.
But if Trappist-1 is able to collect sizeable, rocky planets in its habitable zone, there’s no reason to assume that other tiny stars can’t, too. The universe could be full of tightly-packed solar systems with potentially viable planets. “These questions, about ‘are we alone?’, are being answered as we speak, in this decade and the next decades,” said Thomas Zurbuchen, of NASA.
In the meantime, humanity’s collective imagination is certainly alive, and speeding along at full blast. A website collecting creative works inspired by the discovery already has two short stories, a graphic novel, and a Dr. Seuss-style poem.
Researchers are happily indulging hypotheticals about the Trappist-1 living experience—the planets probably don’t have moons, the sunlight is likely salmon-colored and about as bright as moonglow, and one side of each planet remains dark at all times, they say. NASA has even released a potential tourism poster, based on the fact that the Trappist-1 planets are just a hop away from one another.
If there’s one thing we can expect—from Trappist-1 or whatever comes next—it’s that what we eventually find will outstrip even our wildest imaginings. “It’s very likely nature is way more beautiful and way more amazing than what we’ve animated here,” said Zurbuchen, gesturing at artistic renderings of the Trappist-1 system—sleek, blue-dappled planets dancing around their tiny star. “It’s always that way.”