Webb Telescope Will Look for Signs of Life Way Out There

This month will mark a new chapter in the search for extraterrestrial life, when the most powerful space telescope yet built will start spying on planets that orbit other stars. Astronomers hope that the James Webb Space Telescope will reveal whether some of those planets harbor atmospheres that might support life. New York Times: Identifying an atmosphere in another solar system would be remarkable enough. But there is even a chance -- albeit tiny -- that one of these atmospheres will offer what is known as a biosignature: a signal of life itself. 'I think we will be able to find planets that we think are interesting -- you know, good possibilities for life,' said Megan Mansfield, an astronomer at the University of Arizona. 'But we won't necessarily be able to just identify life immediately.'

So far, Earth remains the only planet in the universe where life is known to exist. Scientists have been sending probes to Mars for almost 60 years and have not yet found Martians. But it is conceivable that life is hiding under the surface of the Red Planet or waiting to be discovered on a moon of Jupiter or Saturn. Some scientists have held out hope that even Venus, despite its scorching atmosphere of sulfur dioxide clouds, might be home to Venusians. Even if Earth turns out to be the only planet harboring life in our own solar system, many other solar systems in the universe hold so-called exoplanets. In 1995, Swiss astronomers spotted the first exoplanet orbiting a sunlike star. Known as 51 Pegasi b, the exoplanet turned out to be an unpromising home for life -- a puffy gas giant bigger than Jupiter, and a toasty 1,800 degrees Fahrenheit. In the years since, scientists have found more than 5,000 other exoplanets. Some of them are far more similar to Earth -- roughly the same size, made of rock rather than gas and orbiting in a 'Goldilocks zone' around their star, not so close as to get cooked but not so far as to be frozen.

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