Which planets beside Land Offer the conditions that make life possible? In the search for the so-called exoplanets, science is well developed, and thousands of such planets have already been discovered. But life on Earth can also be perceived by extraterrestrial beings. So who are we aliens?
Accordingly, scientists have identified 1,715 star systems in our cosmic neighborhood, in which extraterrestrial observers could have discovered the Earth in the past 5,000 years. According to the study, among those who are in a suitable position to observe the transit of the Earth, 46 star systems are close enough that their planets can pick up a clear signal of human presence – radio and television broadcasts that began about 100 years ago.
Look for planets when they block the light of their host star
Researchers estimate that 29 potentially habitable planets are well placed to observe Earth and listen to human radio and television broadcasts. From this, observers can infer a certain level of intelligence. It is doubtful whether the transfers would encourage an advanced civilization to establish contact.
“One way to find planets is to block some of the light from their host star,” Lisa Kaltenegger, professor of astronomy and director of the Carl Sagan Institute at Cornell University in New York, tells The Guardian. “We asked ourselves, ‘Who are we aliens if someone else is looking for her?’” “There’s this little sliver in the sky that allows other star systems to find Earth.”
To find out suitable nearby star systems for observing terrestrial transit, Kaltenegger and D. Jackie Ferti, an astrophysicist at the American Museum of Natural History, referred to the European Space Agency’s Gaia catalog. This contains the positions and movements of the stars. From this, they identified 2,034 star systems within a radius of 100 parsecs (326 light years) that could observe a transit of Earth at any time between 5,000 years ago and 5,000 years in the future.