Scientists using the James Webb space telescope say they’ve found a planet relatively close to Earth that could be the first ever detected with a potentially life-sustaining liquid ocean outside our solar system.
So far, more than 5,000 planets have been discovered outside of the Solar System. However, only a handful are in what is called the “Goldilocks zone,” which is neither too hot nor too cold, and could host liquid water, which is a key ingredient for life.
The exoplanet LHS 1140 b is one of the few in this habitable zone and has been closely examined since it was first discovered in 2017.
It’s about 48 light years from Earth, which is more than 450 trillion kilometres (280 trillion miles) away—pretty close in the vast distances of space.
The exoplanet was previously thought to be a small gas giant, similar to Neptune, with an atmosphere too dense with hydrogen and helium to support alien life.
However, new observations from the Webb telescope have confirmed that the exoplanet is, in fact, a rocky “super-Earth.”
A study published late Wednesday in The Astrophysical Journal Letters found that it is 1.7 times bigger than Earth but has 5.6 times its mass.
The Webb telescope was able to analyze the planet’s atmosphere as it passed in front of its star, which is the “best bet” for an ocean world.
There were no signs of hydrogen or helium, which meant that the planet couldn’t be a mini-Neptune.
The planet’s density suggests it has a lot of water, according to Martin Turbet, a study co-author from France’s CNRS scientific research center, who spoke to AFP.
It could be a truly immense amount of water.
Just to put things in perspective, all the water in Earth’s oceans represents only 0.02 percent of its mass. But it’s thought that 10 to 20 percent of the exoplanet’s mass is made up of water.
It depends on the planet’s atmosphere whether this water is in liquid or ice form.
“We don’t have direct proof that it has an atmosphere, but there are a few things that suggest it might,” Turbet said.
The study’s lead author, Charles Cadieux, a PhD student at the University of Montreal, said that “of all the temperate exoplanets we know about, LHS 1140 b could be our best bet to confirm whether there’s liquid water on the surface of an alien world.”
On the bright side, the planet is gently warmed by its red dwarf star, which is only one-fifth the size of the Sun.
Turbet said the exoplanet’s surface temperature should be pretty similar to Earth and Mars.
The presence of gases like carbon dioxide will be a big factor in determining whether the planet is covered in ice or water.
It’s looking like there might be an ocean under all that ice.
The theory is that the surface is mostly ice, but there’s a vast liquid ocean where the planet is most exposed to its star’s heat.
Modeling suggests that this ocean could be about 4,000 kilometers in diameter, which is around half the surface area of the Atlantic Ocean.
Or the liquid water could be hidden under a thick shell of ice, like on the moons Ganymede, Enceladus, or Europa orbiting around Jupiter and Saturn.
Cadieux said that Webb’s instrument spotted signs that suggest “the presence of nitrogen,” but that more research was needed to confirm the finding.
Nitrogen is found everywhere on Earth, and it’s thought to be another ingredient for life. The researchers are hoping to get a few more hours of the Webb telescope’s time to find out more about LHS 1140 b. It’ll take at least a year to confirm whether the exoplanet has an atmosphere, and two or three more to detect the presence of carbon dioxide, the researchers estimated.
