Aliens could be hiding in special “terminator suns” on distant planets where it’s neither too hot nor too cold, scientists say.
Many exoplanets — planets outside our solar system — are tidally locked, meaning one side always faces the star they orbit and the other side is in permanent darkness.
Astronomers from the University of California, Irvine found that these planets have a belt around them that could potentially harbor liquid water – a key ingredient for life.
This is called the “terminator zone,” with the terminator being the dividing line between the day side and the night side of the exoplanet.
Any feasible water would probably be frozen on the cold night side, but the bright day side would be hot enough to evaporate.
Astronomers at the University of California, Irvine, found that tidally locked exoplants have a band around them that could potentially hold liquid water, a key ingredient for life
Lead author, Dr Ana Lobo said: ‘The day side can be scorching hot, far beyond habitable, and the night side will be frigid, possibly covered in ice.
“You could have big glaciers on the night side.
“You want a planet that is just the right temperature to have liquid water.”
Everything with mass has gravity, and the more massive it is, the stronger the gravity.
In the case of a planet orbiting a star, the star’s gravity pulls the planet toward itself, while the planet’s gravity also pulls it toward the star.
A planet’s orbital path is determined by the combination of these forces, as well as the speed and direction of its motion before entering orbit.
If a planet orbits extremely close to a star, the star’s gravity can distort the shape of the planet so that it bulges out on one side.
The gravity felt by this bulge is stronger than in other regions on the planet, so it begins to slow the planet’s axial rotation.
Eventually this slows down to the point where the rotation stops completely and only the bulging side faces the star, making it tidally locked.
Tidal-locked exoplanets are more likely around “M dwarf” stars, a type of red dwarf that is cooler and smaller than our sun.
This is because smaller stars are more likely to trap smaller exoplanets in their orbits, which are more sensitive to tidal forces than larger ones.
Many exoplanets are tidally locked, meaning that one side always faces the star they orbit, and the other side is in permanent darkness. Pictured: surface temperatures (°C) of several simulated tidally exoplanets. The black lines indicate the terminator
Since M dwarf stars make up about 70 percent of the stars in the night sky, tidally locked exoplanets are believed to be relatively common.
For their study, published in The Astrophysical Journalthe researchers wanted to find out if these planets have life-sustaining conditions, such as the ability to retain water in a liquid form.
If so, this would greatly expand the pool of planets that astronomers could study for extraterrestrial life.
The researchers simulated the climate of a number of tidal exoplanets, looking at their varying temperatures, wind patterns and radiation exposure.
They used software normally used to model Earth’s climate, but slowed down its rotation on its axis.
This highlighted a “just right” zone around the terminator of these planets that could contain liquid water, making life possible.
However, this was only the case if there was a lot of land on the planet, as if it were mostly covered by ocean, the water on the day side would evaporate and cover the planet in vapor.
This would change the temperature of the terminator zone and make it no longer habitable.
“Ana has shown that if there is a lot of land on the planet, the scenario we call ‘terminator habitability’ can exist much more easily,” says co-author Dr Aomawa Shields.
“These new and exotic habitability states that our team is discovering are no longer the stuff of science fiction – Ana has done the work to show that such states can be climatically stable.”
Most studies that have assessed the potential for life look at water-rich planets.
Dr. Lobo said, “We’re trying to draw attention to more water-restricted planets, which, despite not having vast oceans, could have lakes or other smaller amounts of liquid water, and these climates could actually be promising.”
The researchers say they believe this is the first time astronomers have proven there is potential for life in the terminator zone of exoplanets.
Their finding may mean that scientists looking for signs of life on exoplanets should be aware that they may be hidden in specific areas.
It has also expanded the scope of planets that can be searched to planets that are not mostly covered by water.
“By exploring these exotic climatic states, we increase our chances of finding and correctly identifying a habitable planet in the near future,” said Dr Lobo.
KEY DISCOVERIES IN MAN’S SEARCH FOR LIFE FOREIGN
Discovery of pulsars
British astronomer Dame Jocelyn Bell Burnell was the first person to discover a pulsar in 1967 when she saw a radio pulsar.
Since then, other types of pulsars that emit X-rays and gamma rays have also been observed.
Pulsars are essentially rotating, highly magnetized neutron stars, but when they were first discovered it was thought that they might have come from aliens.
‘Wow!’ radio signal
In 1977, an astronomer looking for extraterrestrial life in the night sky over Ohio saw a radio signal so powerful that he excitedly shouted “Wow!” wrote. next to his data.
In 1977, an astronomer looking for extraterrestrial life in the night sky over Ohio saw a radio signal so powerful that he excitedly shouted “Wow!” wrote. next to his data
The 72-second blast, observed by Dr. Jerry Ehman through a radio telescope, came from Sagittarius but matched no known celestial body.
Conspiracy theorists have since argued that the ‘Wow! signal’, which was 30 times stronger than background radiation, was a message from intelligent aliens.
Fossilized microbes from Mars
In 1996, NASA and the White House made the explosive announcement that the rock contained traces of Martian insects.
The meteorite, cataloged as Allen Hills (ALH) 84001, crashed into the frozen wasteland of Antarctica 13,000 years ago and was recovered in 1984.
Photos were released of elongated segmented objects that appeared remarkably lifelike.
Photos have been released of elongated segmented objects that appeared remarkably lifelike (photo)
However, the excitement did not last long. Other scientists wondered if the meteorite samples were contaminated.
They also argued that the heat generated when the rock was blasted into space may have created mineral structures that could be mistaken for microfossils.
Behavior of Tabby’s Star in 2005
Also known as KIC 8462852, the star is located 1,400 light-years away and has baffled astronomers since its discovery in 2015.
It dims much faster than other stars, which some experts say is a sign that aliens are harnessing a star’s energy.
Also known as KIC 8462852, the star is 1,400 light-years away and has baffled astronomers since its discovery in 2015 (artist’s impression)
Recent studies have “eliminated the possibility of an alien megastructure,” suggesting instead that a ring of dust could be causing the strange signals.
Exoplanets in the Goldilocks zone in 2017
In February 2017, astronomers announced they had spotted a galaxy with planets that could support life just 39 light-years away.
Seven Earth-sized planets have been discovered orbiting the nearby dwarf star Trappist-1, and all may have water on their surface, one of the main components of life.
Three of the planets have such good conditions that scientists say life has already evolved on them.
Researchers claim they will know within ten years if there is life on any of the planets, saying, “This is just the beginning.”
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