A team at Cornell University reveal that aliens, specifically located in 1,715 nearby star systems, could have already seen Earth by watching our planet cross the Sun
The scientists reveal that 1,715 star-systems could have spotted Earth, since human civilisation kicked in around 5,000 years ago. The Earth passing by the Sun, a pale blue dot, would evoke curiosity in those out there looking for a habitable planet.
By watching distant exoplanets transit – or cross – their own sun, Earth’s astronomers can interpret the atmospheres backlit by that sun. If exoplanets hold intelligent life, they can observe Earth via by the sun and see our atmosphere’s chemical signatures of life.
‘We are the aliens’, says Professor Kaltenegger
Lisa Kaltenegger, professor of astronomy and director of Cornell’s Carl Sagan Institute, in the College of Arts and Sciences, said: “From the exoplanets’ point-of-view, we are the aliens.
“We wanted to know which stars have the right vantage point to see Earth, as it blocks the Sun’s light. And because stars move in our dynamic cosmos, this vantage point is gained and lost.”
Earth Transit Zone has significant visitors
Kaltenegger and astrophysicist Jackie Faherty, a senior scientist at the American Museum of Natural History, used positions and motions from the European Space Agency’s Gaia eDR3 catalogue to determine which stars enter and exit the Earth Transit Zone.
Faherty said: “Gaia has provided us with a precise map of the Milky Way galaxy, allowing us to look backward and forward in time, and to see where stars had been located and where they are going.”
Of the 2,034 star-systems passing through the Earth Transit Zone over the 10,000-year period examined, 117 objects lie within about 100 light-years of the sun and 75 of these objects have been in the Earth Transit Zone since commercial radio stations on Earth began broadcasting into space about a century ago.
The Breakthrough Starshot initiative is an ambitious project, which would mean launching a nano-sized spacecraft toward the closest exoplanet detected around Proxima Centauri – 4.2 light-years from us. On Earth, we are reaching to habitable planets and looking for signs of intelligent life.
“One might imagine that worlds beyond Earth that have already detected us, are making the same plans for our planet and solar system,” said Faherty.
“This catalog is an intriguing thought experiment for which one of our neighbors might be able to find us.”
