ASTRONOMERS HAVE come up with a new way to search for advanced life on distant planets: look for the light given off by their cities. This could help us pinpoint intelligent extraterrestrials.
“This method opens a new window in the search for extraterrestrial civilisations,” say Abraham Loeb of Harvard University and Edwin Turner of Princeton University.
The rush to discover planets orbiting stars in distant galaxies has turned up 687 of them as of yesterday. The hope is we might find a home away from home, an Earth-like planet that might harbour life similar to ourselves.
But how would we know if it was there? The two astronomers believe big telescopes could help us detect artificial light coming from the dark side of these planets. They explain how in a research paper submitted to the journal Astrobiology. It might seem fanciful, but in fact we can already do this. Sunlight has a different signature to artificial light so would be easy to spot, they say.
Today’s telescopes can detect the light spectrum coming from objects at the very edge of our solar system 7.5 billion km away and probably farther if there was anything nearby to look at. The real challenge, though, is the distances involved when trying to observe planets that are millions of light years away.
For this reason the scientists, who for decades have watched for any sign of ET under the Search for Extra-Terrestrial Intelligence programme, have depended on listening for incoming radio waves, a sure sign of intelligent life somewhere out there.
The astronomers point out, however, that if there is an advanced civilisation out there making use of radio technology, then the signal this technology bounces out into space may be getting weaker. This is happening on Earth, Loeb and Turner say. As technology changes our own radio signal is fading.
For this reason they believe we should develop ways to spot ET’s home planet by looking for artificial illumination. Light at night is a basic need so if there is any advanced life out there, it would be inclined to switch on the street lights. “Artificial illumination may serve as a lamp post which signals the existence of extraterrestrial technologies and thus civilisations,” they write.
They admit finding any intelligent life would be “a long shot” and would probably have to wait until the next generation of more powerful telescopes. But finding artificial light could only mean one thing – and change our perspective of our place in the universe.