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Could we find alien civilizations using infrared light?

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Instead of listening for radio signals, a group of astronomers is proposing that we search for extraterrestrials by detecting their planet’s exaggerated heat signatures — signatures that could be detected in the infrared. But to do so, we’d have to build the largest telescope this world has ever seen.

Writing in Astronomy Magazine, a team of astronomers, engineers, and physicists from the University of Hawaii, the University of Freiburg, and elsewhere is making the case for infrared SETI. The basic idea is that a sufficiently advanced extraterrestrial civilization will produce more power on its planet than it receives from its parent star. This delta in energy could indicate the presence of an alien civilization.

"The energy footprint of life and civilization appears as infrared heat radiation," says Jeff Kuhn, the project's lead scientist. "A convenient way to describe the strength of this signal is in terms of total stellar power that is incident on the host planet."


Thus, given a large enough telescope — and one that’s designed specifically for infrared detection — astronomers could scan the heavens for planets within a 60 light-year radius.

And indeed, there is already a proposal on the table for one such telescope: The Colossus.


Space Daily describes the telescope:

The quest for direct infrared detection of extraterrestrial civilizations, along with many other research possibilities, has led the team to the funding and building of a giant telescope. Currently planned large infrared telescopes, the Giant Magellan Telescope, the Thirty Meter Telescope, and the European Extremely Large Telescope, would not be large enough.

Instead, a telescope (dubbed Colossus) with a primary mirror about 250 feet (77 meters) in diameter could find hundreds of Earth-sized or larger planets in habitable zones, and perhaps dozens of extraterrestrial civilizations, by using a sensitive coronagraph — and the technology to build such an instrument exists.

The international team thus seeks funding to build a 77-m telescope, which would be constructed from revolutionary thin-mirror slumping and polishing technologies developed by the Innovative Optics team. The telescope would consist of approximately sixty 8-m mirror segments, and would operate at a high-altitude site.


In addition, the telescope could be used to study stellar surfaces, black holes, and quasars.

Read the entire report at Astronomy: “How to find ET with infrared light.”

Image by NASA/JPL. Telescope via Innovative Optics.