Some exoplanets may also be able to see us – ScienceDaily

Lisa Kaltenegger, associate professor of astronomy at Cornell University and director of the Carl Sagan Institute, Cornell; and Joshua Pepper, Associate Professor of Physics at Lehigh University, have identified 1,004 main sequence stars (similar to our Sun) that might contain Earth-like planets in their own habitable zones – all within about 300 light years of the Earth – and that are capable should be able to recognize the chemical traces of life on earth.

The paper “Which stars can see the earth as transit exoplanets?” Was published in the Monthly announcements from the Royal Astronomical Society.

“Let us reverse the perspective to that of other stars and ask from which point of view other observers could find the earth as a transit planet,” said Kaltenegger. A transit planet is a planet that passes through the observer’s line of sight to another star, such as the sun, and provides clues about the composition of the planet’s atmosphere.

“If observers looked out there, they could see signs of a biosphere in the atmosphere of our light blue point,” she said. “And we can even see some of the brightest of these stars in our night sky without binoculars or telescopes. ”

Transit observations are a crucial tool for Earth’s astronomers to characterize inhabited extrasolar planets, said Kaltenegger, which astronomers will use with NASA’s James Webb Space Telescope launch next year.

But which star systems could find us? The key to this science is the earth’s ecliptic – the plane of the earth’s orbit around the sun. In the ecliptic, the exoplanets would be facing the earth as they will be the places where the earth can cross its own sun. In this way, observers can effectively discover the living biosphere of our planet.

Pepper and Kaltenegger compiled the list of the thousand closest stars using NASA’s TESS star catalog (Transiting Exoplanet Survey Satellite).

“Only a very small fraction of the exoplanets are randomly aligned with our line of sight so that we can see them in transit,” said Pepper. “But all of the thousands of stars that we identified in our newspaper in the sun’s surroundings could see our earth cross the sun and get their attention.”

“If we were to find a planet with a living biosphere, we would be curious whether someone was looking at us or not,” said Kaltenegger.

“If we’re looking for intelligent life in the universe, that might find us and want to contact us,” she said, “we’ve just created the star map where to look first.”

This work was funded by the Carl Sagan Institute and the Breakthrough Initiative.

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Materials provided by Cornell University. Originally written by Blaine Friedlander. Note: The content can be edited by style and length.