TORONTO – The first lunar eclipse ever observed by the Hubble Space Telescope provides a near-home example of how astronomers will look for signs of life on Earth — like planets in distant solar systems.
Scientists with the European Space Agency (ESA) announced on Thursday that the spacecraft telescope was able to use the ultraviolet spectral signature of the Earth’s terrestrial ozone layer in the lunar form of January 2019 by using the moon as a mirror to to reflect sunlight.
“This is the first time a total lunar eclipse has been captured from a space telescope and the first time such an eclipse has been studied in ultraviolet wavelengths,” the ESA team said in a statement.
The Hubble is not normally towards the moon; instead, it is focused on objects a much greater distance from Earth. It is no coincidence that the eclipse was captured by the telescope, although no one had been before. It was part of an experiment set up to test what the telescope would capture during a lunar eclipse, which mimics conditions that could be used to photograph planets remotely.
The key to the experiment was ozone, the gas that protects all life forms from harsh exposure to the sun’s UV rays and is therefore seen as an essential ingredient for life elsewhere. The Earth’s ozone layer has been discovered in the past during lunar eclipses, but always from our side – which means that it was accompanied by disturbance of other parts of the atmosphere.
The Hubble was able to eliminate this disturbance by scanning for UV light that jumped the moon during the eclipse. According to the ESA, this resulted in the strongest detection ever of the earth’s ozone layer.
Telescopes larger than the Hubble are currently in development. Once complete, they will be used to study planets outside our solar system – including by scanning for ozone, now that Hubble’s experiment can be considered a success, the ESA said.
Instead of eclipses, however, scientists will give their experiments time to reboot – the periods when the geometry of starlight filtering through the atmosphere of a planet results in a halo-like glow around the planet.
The first of these new telescopes is the James Webb Space Telescope, which was developed in part by the Canadian Space Agency. It is expected to launch in 2021.
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