Ever since humans looked up at the stars, we have always been curious about life beyond Earth.
But this exploration may soon come to an end, as scientists have discovered a planet that may be our "best choice" for finding extraterrestrial life in the universe.
Using observations from NASA's James Webb Space Telescope (JWST), an international team of scientists has analyzed the atmosphere of an exoplanet called LHS 1140 b.
Their observations confirmed that the proximity planet may have oceans of liquid water and even a nitrogen-rich atmosphere – just like Earth.
Lead author Charles Cadieux from the University of Montreal said: "Of all the known extratropical exoplanets, LHS 1140 b may be our best choice to indirectly confirm the presence of liquid water on the surface of extrasolar planets. ”
Although we don't know exactly what extraterrestrial life would look like, scientists are almost certain that it will need liquid water to survive.
The exoplanet LHS 1140 b is located in the constellation Cetus and is located 48 light-years from Earth.
This makes it the closest planet to us within the "habitable zone" of its star – an area where water can exist in liquid form.
The exoplanet, which is about six times the mass of Earth, orbits a small red dwarf star about one-fifth the size of our sun, and is cool enough to potentially form water.
Recent analyses have shown that the mass of this exoplanet is much lower than it should be for its size.
This leaves the researchers with two options: either LHS 1140 b is a "mini-Neptune" composed mostly of rotating gas, or it is a "super-Earth" covered in liquid or frozen water.
To determine which was the case, the researchers combined data from JWST and other space telescopes, such as Hubble and Spitzer, to perform the first "spectral" analysis of LHS 1140 b.
Since certain molecules block different wavelengths of light, by measuring the frequency of light passing through the planet, we can understand the chemicals that may be present.
Their analysis suggests that LHS 1140 b is more likely to be a "water world" or "snowball" with a rocky core than a gaseous mini-Neptune.
What's even more exciting is that preliminary analysis suggests that the exoplanet may even have a thick atmosphere, just like on Earth.
This will give it a greater ability to retain the heat of its stars and make it more likely to have a stable climate – all important factors for the existence of life.
Dr Ryan MacDonald, an astronomer at the University of Michigan who participated in the study, said: "This is the first time we have seen signs of an atmosphere on rocky or ice-rich exoplanets within the habitable zone. ”
Although they warn that more observations from JWST are needed, this atmosphere could be rich in nitrogen, which makes up 78% of the Earth's atmosphere.
Dr. MacDonald added: "LHS 1140 b is one of the best small exoplanets in the habitable zone to support a thick atmosphere, and we may have just found evidence of the presence of air on this planet. ”
Just like the Moon's orbit around the Earth, LHS 1140 b has a synchronous orbit, which means that one side is always facing away from its star.
While researchers believe that the exoplanet is likely to be a frozen "snowball," this means that there may be liquid water on the heated side of its star.
If LHS 1140 b does have an atmosphere, it may possess a "bullseye ocean" about 2,400 miles (4,000 km) in diameter – equivalent to half the surface area of the Atlantic Ocean.
And, the surface temperature of this ocean is likely to be a warm 20°C (68°F), which is close to the high end of the British ocean temperature in the summer.
While this is not the first planet to be found within the habitable zone of its star, it does provide scientists with one of the best opportunities for further research.
The stars orbited by this exoplanet are relatively calm compared to the stars that orbit the exoplanets within the TRAPPIST-1 system.
This makes it easier to separate the effects caused by its atmosphere from the random noise of sunspots and solar flares.
Researchers say this presents a unique opportunity to study a planet that could support life.