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Hubble uses eclipse to practice hunt for alien life

Astronomers made use of the Hubble Space Telescope — and a total lunar eclipse — to rehearse their routine for seeking signs of life in alien atmospheres.

You’ll be relieved to know that the experiment, conducted on Jan. 20-21, 2019, determined that there are indeed signs of life on Earth.

The evidence came in the form of a strong spectral fingerprint for ozone. To detect that ultraviolet fingerprint, Hubble didn’t look at Earth directly. Instead, it analyzed the dim reddish light that was first refracted by Earth’s atmosphere, and then reflected back by the moon during last year’s lunar eclipse.

“Finding ozone is significant because it is a photochemical byproduct of molecular oxygen, which is itself a byproduct of life,” said Allison Youngblood of the Laboratory for Atmospheric and Space Physics in Boulder, Colo., lead researcher of Hubble’s observations.

Other ground-based telescopes made spectroscopic observations at other wavelengths during the eclipse. They were looking for the fingerprints of different atmospheric ingredients linked to life’s presence, such as oxygen and methane.

This wasn’t just an academic exercise. Astronomers hope future observatories, such as the James Webb Space Telescope and the Roman Space Telescope, will be able to detect life’s fingerprints in the atmospheres of faraway exoplanets. But that takes practice.

“One of NASA’s major goals is to identify planets that could support life,” Youngblood said in a Hubble news release. “But how would we know a habitable or an uninhabited planet if we saw one? What would they look like with the techniques that astronomers have at their disposal for characterizing the atmospheres of exoplanets? That’s why it’s important to develop models of Earth’s spectrum as a template for categorizing atmospheres on extrasolar planets.”

Check out the news release for further details, or delve into the research paper published today in The Astronomical Journal. And to learn more about how lunar eclipses work, check out this “Inconstant Moon” interactive (after you enable Flash in your browser).

This report was published on Cosmic Log. Accept no substitutes.

By Alan Boyle

Mastermind of Cosmic Log, contributing editor at GeekWire, author of "The Case for Pluto: How a Little Planet Made a Big Difference," president of the Council for the Advancement of Science Writing. Check out "About Alan Boyle" for more fun facts.

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