An artist’s impression of the Hubble Space Telescope capturing reflected sunlight from the moon during a total lunar eclipse. Image: Image: M. Kornmesser (ESA/Hubble), NASA and ESA
Testing techniques that one day could be used to detect the presence of biosignatures in exoplanet atmospheres, the Hubble Space Telescope took advantage of a total lunar eclipse to collect ultraviolet spectra of sunlight passing through Earth’s atmosphere on its way to the moon. Hubble was able to detect the presence of ozone in sunlight reflecting off the eclipsed moon, a first for a space-based telescope.
“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, Colorado, who led the research.
The spectra of sunlight passing through the atmosphere of an exoplanet as it moves in front of its parent star is affected by interactions with the chemicals in that atmosphere. Similarly, the spectra captured by Hubble included the tell-tale effects of ozone.
Ozone forms when oxygen is exposed to strong ultraviolet radiation, which triggers the necessary chemical reactions. Photosynthesis over billions of years generated high oxygen levels and the ...