We could spot advanced aliens that are similar to us by monitoring for signs of 'space junk' orbiting distant planets, claims scientist
- Astronomers often use the 'transit method' to find exoplanets
- This is where light from a star observably dips as a planet travels in front of it
- One expert has suggested we could use this same method to spot space junk
- Collective junk might block out some of the star's light
- In order for a dip to be visible from tens of light years away, there would need to be between ten billion and one trillion satellites
We could find advanced alien life by monitoring for signs of 'space junk' orbiting distant worlds, a scientist has claimed.
Astronomers often use the 'transit method' - where light from a star observably dips as a planet travels in front of it - to find exoplanets.
One expert has now suggested we could use this same method to spot space junk such as satellites, solar panels and other objects in geostationary orbit.
If another planet has as much space junk as Earth is predicted to have by 2200 then this method could already be used to spot distant alien civilisations.
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We could find advanced alien life by monitoring signs of 'space junk' (artist's impression), a scientist has claimed. Astronomers often use the 'transit method' - where light from a star observably dips as a planet travels in front of it - to find exoplanets
Using the transit method, experts can already make estimates about features of other planets based on their orbits and the time taken for each transit, according to New Scientist.
Writing in arXiv preprint article, astrophysicist Hector Socas-Navarro from the Canary Islands Institute of Astrophysics in Spain claims this same method could indicate how technologically advanced an alien life is.
He says this is because collective junk - which he termed a 'Clarke Exobelt' (CEB) - might block out some of the star's light.
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In order for a dip to be visible from tens of light years away, there would need to be between ten billion and one trillion satellites.
Currently on Earth there are only a few thousand. However, over the past 15 years, the opacity of the Earth's Clarke belt has increased exponentially.
Although it might be very difficult to spot such minimal dimming of light, if there was enough junk it would show up with current telescopes.
He calculated that if TRAPPIST-1 exoplanets had as much clutter as Earth will have in 2200 we might be able to see its CEB now, writes Real Clear Science.
Pictured is an illustrative sketch of a planet with a CEB transiting its parent star. The size and surface density of the individual objects has been exaggerated for better visualisation
He calculated that if TRAPPIST-1 exoplanets (artist's impression) had as much clutter as Earth will have in 2200 we might be able to see its CEB now
If scientists know the mass and rotation period of a planet they will be able to determine the radius of the Clarke belt.
'The idea is to examine the region of space around a planet where potential geostationary or geosynchronous satellites would orbit (herafter, the Clarke exobelt)', wrote Dr Socas-Navarro in his paper.
'Civilisations with a high density of devices and/or space junk in that region, but otherwise similar to ours in terms of space technology (our working definition of 'moderately advanced'), may leave a noticeable imprint on the light curve of the parent star', he said.
One problem with this method is that space junk might be difficult to distinguish from natural debris.
Rings and moons around other planets would probably also give similar signals, although experts have not found any on exoplanets yet.
'The nice thing is that looking for Clarke exobelts comes for free with the search for moons and rings,' Socas-Navarro told New Scientist.
'It's as if someone gives you a free lottery ticket. You know it's utterly unlikely that you'll win the prize but wouldn't you check, just in case?'
KEY DISCOVERIES IN HUMANITY'S SEARCH FOR ALIEN LIFE
Discovery of pulsars
British astronomer Dame Jocelyn Bell Burnell was the first person to discover a pulsar in 1967 when she spotted a radio pulsar.
Since then other types of pulsars that emit X-rays and gamma rays have also been spotted.
Pulsars are essentially rotating, highly magnetised neutron stars but when they were first discovered it was believed they could have come from aliens.
'Wow!' radio signal
In 1977, an astronomer looking for alien life in the night sky above Ohio spotted a radio signal so powerful that he excitedly wrote 'Wow!' next to his data.
In 1977, an astronomer looking for alien life in the night sky above Ohio spotted a radio signal so powerful that he excitedly wrote 'Wow!' next to his data
The 72-second blast, spotted by Dr Jerry Ehman through a radio telescope, came from Sagittarius but matched no known celestial object.
Conspiracy theorists have since claimed that the 'Wow! signal', which was 30 times stronger than background radiation, was a message from intelligent extraterrestrials.
Fossilised Martian microbes
In 1996 Nasa and the White House made the explosive announcement that the rock contained traces of Martian bugs.
The meteorite, catalogued as Allen Hills (ALH) 84001, crashed onto the frozen wastes of Antarctica 13,000 years ago and was recovered in 1984.
Photographs were released showing elongated segmented objects that appeared strikingly lifelike.
Photographs were released showing elongated segmented objects that appeared strikingly lifelike (pictured)
However, the excitement did not last long. Other scientists questioned whether the meteorite samples were contaminated.
They also argued that heat generated when the rock was blasted into space may have created mineral structures that could be mistaken for microfossils.
Behaviour of Tabby's Star in 2005
The star, otherwise known as KIC 8462852, is located 1,400 light years away and has baffled astronomers since being discovered in 2015.
It dims at a much faster rate than other stars, which some experts have suggested is a sign of aliens harnessing the energy of a star.
The star, otherwise known as KIC 8462852, is located 1,400 light years away and has baffled astonomers since being discovered in 2015 (artist's impression)
Recent studies have 'eliminated the possibility of an alien megastructure', and instead, suggests 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 star system with planets that could support life just 39 light years away.
Seven Earth-like planets were discovered orbiting nearby dwarf star 'Trappist-1', and all of them could have water at their surface, one of the key components of life.
Three of the planets have such good conditions, that scientists say life may have already evolved on them.
Researchers claim that they will know whether or not there is life on any of the planets within a decade, and said: 'This is just the beginning.'
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