NASA and a Belgian-led research team announced a major discovery Wednesday that’s being dubbed “a giant accelerated leap forward in the search for habitable worlds and life on other worlds.”
A cluster of seven planets has been spotted about 40 light-years away, in the constellation Aquarius, orbiting tightly around a single star called Trappist-1.
Here’s what we know, and what scientists still need to find out.
What does the system look like?
The seven planets circle tightly around Trappist-1, a dim dwarf star that’s barely the size of Jupiter. The planet that’s furthest from the star still only has an orbit of about 20 Earth days.
The one closest to the star circles it every 1.5 Earth days.
WATCH: NASA scientist explains makeup of seven Earth-like exoplanets
All seven of the worlds are closer to their parent star than our own sun’s closest planet, Mercury. But because the star is far cooler, they don’t burn up.
The planets probably don’t spin, according to NASA. Instead, they face the star on the same side at all times, meaning it’s always dark on one side and always light on the other. That means if anyone is living there, they likely experience very different weather patterns than the ones we see here on Earth.
WATCH: NASA finds possible link to life on newly discovered planets. Eric Sorensen reports
The Trappist-1 worlds are so close together in their orbits that from the surface of one, the others would appear as big as the Earth’s moon, or larger. You might even be able to spot geological features on the surface of your nearest neighbour.
Is there life?
Maybe, but we’re not sure yet.
Three of the Trappist-1 planets (1e, 1f and 1g) are in the so-called habitable zone, where water and, possibly life, might exist.
There’s a good chance there’s water on those three planets, and some chance of water on the others.
Scientists say they need to study the atmospheres before they can say for certain whether one or more planets could support some type of life.
WATCH: NASA scientist explains findings from within the ‘habitable zone’
Trappist-1e is very close in size to Earth, and gets about the same amount of light. Trappist-1f is a little further from the star, but its orbit still lasts only nine days. It gets about the same amount of light as Mars.
Trappist-1g is the largest planet in the system, with a radius 13 per cent larger than Earth’s.
Can we visit?
If humans could travel at the speed of light, we could reach the system in about 39 years, the researchers said. But with current technology, it would take far longer.
The space probe Voyager 1, which is exiting the solar system at 62,000 kilometres per hour, would take about 700,000 years to reach Trappist-1.