Scientists have proposed what seems like an obvious solution to finding life on other planets—look for pollution similar to that found on Earth. Light or air pollution would be a dead giveaway to life on another planet, according to a study to appear in the journal Astrobiology. Of course, this is assuming that extraterrestrial life is even remotely similar to ours, and even if it is, finding the pollution won't be easy, according to
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Even if all the electricity we generate was used to produce light, it would still be thousands of times fainter than the glint of sunlight reflected from Earth's surface. To reliably detect even this massive amount of artificial light on a planet orbiting a relatively nearby star—say 15 light years away—would require an array of telescopes with a combined light-collecting area of 1.5 square kilometres....
That's about 370 football fields' worth of telescopes. ...