The Hubble Space Telescope has demonstrated a new way to learn more about exoplanets by observing a total lunar eclipse from space.
Astronomers thought it possible to test a new detection method by experimenting with Hubble. When the earth moves exactly between the sun and moon in a lunar eclipse, the moon is blocked by its shadow. A similar thing happens when an exoplanet passes between Earth and a distant star.
So the astronomers checked to see if they could find facts about the earth by observing the moon, using it as a mirror, and seeing it reflecting the sunlight. The light had passed through the earth's atmosphere, which it filters, and by observing the light reflected from the moon, they could draw conclusions about the earth.
Astronomers using the NASA / ESA Hubble Space Telescope will use the total lunar eclipse in January 2019 to measure the amount of ozone in the Earth's atmosphere. This method acts as a proxy for how they observe Earth-like planets wandering off other stars in search of life. The perfect alignment of our planet with the sun and moon during a total lunar eclipse mimics the geometry of a continuous terrestrial planet with its star ESA / Hubble, M. Kornmesser
Using this method, they were able to determine the presence of ozone in the earth's atmosphere by observing the moon. This is important in that ozone is related to the presence of life, with most of the ozone in our atmosphere being produced by photosynthesis and the gas playing an important role in protecting the earth from cosmic rays.
If this method were used to observe exoplanets, we could possibly see ozone there too. "Locating ozone in the spectrum of an exo-earth would be important because it is a photochemical by-product of molecular oxygen that is a by-product of life," said Allison Youngblood of the Laboratory for Atmospheric and Space Physics, senior researcher at Hubbles Observations in an opinion.
Future space telescopes like the upcoming James Webb Space Telescope could use this method to study the atmosphere of exoplanets, including rocky Earth-like planets, which is very difficult with current telescopes and methods. There could even be clues as to where to look for potentially habitable planets first. This study serves as evidence of the concept for the time being when we consider our own planet.
"In order to fully characterize exoplanets, we will ideally use a variety of techniques and wavelengths," said team member Antonio Garcia Munoz from the Technical University of Berlin in Germany in the statement. This study clearly shows the advantages of ultraviolet spectroscopy in characterizing exoplanets. It also shows the importance of testing innovative ideas and methods with the only habitable planet we know so far! "