Image of the Day: Lights of Alien Civilizations --The New ET Search Beacon?
The image above taken from the International Space Station shows the lights of one of Earth's oldest civilizations --Egypt's Cairo and the Nile Delta. If an alien civilization builds brightly-lit cities like those shown above, future generations of telescopes might allow us to detect them. This would offer a new method of searching for extraterrestrial intelligence elsewhere in our Galaxy.
In the search for extraterrestrial intelligence, astronomers have hunted for radio signals and ultra-short laser pulses, but Avi Loeb (Harvard-Smithsonian Center for Astrophysics) and Edwin Turner (Princeton University) suggest that we look for their urban lights.
"Looking for alien cities would be a long shot, but wouldn't require extra resources. And if we succeed, it would change our perception of our place in the universe," said Loeb.
As with other SETI methods, they rely on the assumption that aliens would use Earth-like technologies. This is reasonable because any intelligent life that evolved in the light from its nearest star is likely to have artificial illumination that switches on during the hours of darkness.
How easy would it be to spot a city on a distant planet? Clearly, this light will have to be distinguished from the glare from the parent star. Loeb and Turner suggest looking at the change in light from an exoplanet as it moves around its star.
As the planet orbits, it goes through phases similar to those of the Moon. When it's in a dark phase, more artificial light from the night side would be visible from Earth than reflected light from the day side. So the total flux from a planet with city lighting will vary in a way that is measurably different from a planet that has no artificial lights.
Spotting this tiny signal would require future generations of telescopes. However, the technique could be tested closer to home, using objects at the edge of our solar system.
Loeb and Turner calculate that today's best telescopes ought to be able to see the light generated by a Tokyo-sized metropolis at the distance of the Kuiper Belt - the region occupied by Pluto, Eris, and thousands of smaller icy bodies. So if there are any cities out there, we ought to be able to see them now. By looking, astronomers can hone the technique and be ready to apply it when the first Earth-sized worlds are found around distant stars in our galaxy.
"It's very unlikely that there are alien cities on the edge of our solar system, but the principle of science is to find a method to check," Turner said. "Before Galileo, it was conventional wisdom that heavier objects fall faster than light objects, but he tested the belief and found they actually fall at the same rate."
As our technology has moved from radio and TV broadcasts to cable and fiber optics, we have become less detectable to aliens. If the same is true of extraterrestrial civilizations, then artificial lights might be the best way to spot them from afar.
The Daily Galaxy via Harvard-Smithsonian Center for Astrophysics
"Looking for alien cities would be a long shot, but wouldn't require extra resources. And if we succeed, it would change our perception of our place in the universe," said Loeb.
As with other SETI methods, they rely on the assumption that aliens would use Earth-like technologies. This is reasonable because any intelligent life that evolved in the light from its nearest star is likely to have artificial illumination that switches on during the hours of darkness.
How easy would it be to spot a city on a distant planet? Clearly, this light will have to be distinguished from the glare from the parent star. Loeb and Turner suggest looking at the change in light from an exoplanet as it moves around its star.
As the planet orbits, it goes through phases similar to those of the Moon. When it's in a dark phase, more artificial light from the night side would be visible from Earth than reflected light from the day side. So the total flux from a planet with city lighting will vary in a way that is measurably different from a planet that has no artificial lights.
Spotting this tiny signal would require future generations of telescopes. However, the technique could be tested closer to home, using objects at the edge of our solar system.
Loeb and Turner calculate that today's best telescopes ought to be able to see the light generated by a Tokyo-sized metropolis at the distance of the Kuiper Belt - the region occupied by Pluto, Eris, and thousands of smaller icy bodies. So if there are any cities out there, we ought to be able to see them now. By looking, astronomers can hone the technique and be ready to apply it when the first Earth-sized worlds are found around distant stars in our galaxy.
"It's very unlikely that there are alien cities on the edge of our solar system, but the principle of science is to find a method to check," Turner said. "Before Galileo, it was conventional wisdom that heavier objects fall faster than light objects, but he tested the belief and found they actually fall at the same rate."
As our technology has moved from radio and TV broadcasts to cable and fiber optics, we have become less detectable to aliens. If the same is true of extraterrestrial civilizations, then artificial lights might be the best way to spot them from afar.
The Daily Galaxy via Harvard-Smithsonian Center for Astrophysics
Comments
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This post completely ignores so many possibilities. What if Aliens are Nocturnal? What if Aliens don't use visible light to see? What if Aliens use senses that were never developed on earth
Posted by: Mikey | November 04, 2011 at 06:36 AM
So many 'what if's Mikey... At least we would stand some chance of detecting 'humanlike' aliens which is a start. Got to start somewhere...
Posted by: Iain Robertson | November 04, 2011 at 09:46 AM
Excellent idea.
Posted by: Brandon lea | November 05, 2011 at 07:09 PM
of course the E.T lifeforms may have evolved different types of sight than us which negates the need for lighting.
Posted by: zaneth | November 07, 2011 at 10:13 AM
So 'what if' someone out there is using the same techniques to look in our direct? :D Just askin'.
Posted by: Okara | November 08, 2011 at 03:57 PM
When a friend started writing apps for Apple's iDevices, I thought:"Wow! He's a rock star!" Now, after a 3 month learning curve, I'm a rock star. If you want to be one too, read on.
Posted by: Chanel Classic bags | December 04, 2011 at 07:56 PM