For centuries, Earthlings have gazed at the heavens and wondered about life among the stars. But as the humans hunted down the little green men, the aliens could have been watching us.
In new research, astronomers have compiled a shortlist of nearby star systems where any curious inhabitant of orbiting planets would be in a good position to spot life on Earth.
Scientists have identified 1,715 star systems in our cosmic neighborhood where alien observers may have discovered Earth over the past 5,000 years by watching it “transit” across the face of the sun.
Of those well placed to observe an earth transit, 46 star systems are close enough that their planets intercept a clear signal of human existence – the radio and television broadcasts that began about 100 years ago.
Researchers estimate that 29 potentially habitable planets are well placed to witness terrestrial transit and listen to human radio and television transmissions, allowing any observer to infer perhaps a minimum of intelligence. Whether the broadcasts would force an advanced civilization to make contact is a moot point.
“One way to find planets is to block some of the light from their host star,” said Lisa Kaltenegger, professor of astronomy and director of the Carl Sagan Institute at Cornell University in New York. “We asked, ‘Who would we be aliens for if someone else was looking?’ There’s this little shard in the sky where other star systems have a cosmic front seat to find Earth as a planet in transit.
Terrestrial astronomers have detected thousands of planets beyond the solar system. About 70% are spotted when alien worlds pass by their host stars and block some of the light reaching scientists’ telescopes. Future observatories, such as NASA’s James Webb Space Telescope, which is scheduled to launch this year, will look for signs of life on “exoplanets” by analyzing the composition of their atmospheres.
To determine which nearby star systems are well-placed to observe Earth transit, Kaltenegger and Dr. Jackie Faherty, an astrophysicist at the American Museum of Natural History, turned to the Agency’s Gaia catalog of star positions and motions. European space. From this, they identified 2,034 star systems within a radius of 100 parsecs (326 light years) that could spot a terrestrial transit at any time, 5,000 years ago to 5,000 years in the future.
A star known as Ross 128, a red dwarf in the constellation Virgo, is about 11 light years away – close enough to receive emissions from Earth – and has a planet almost twice the size of Earth. Any properly equipped life on the planet could have spotted a terrestrial transit for over 2,000 years, but lost sight 900 years ago. If there is intelligent life on either of the two known planets orbiting the star of Teegarden, 12.5 light years away, it will be in a prime position to observe Earth transit in 29 years. .
45 light years away, another star called Trappist-1 is also close enough to listen to human broadcasts. The star is home to at least seven planets, four of which are in the temperate and habitable zone, but they won’t be able to witness terrestrial transit until 1642 years, scientists write in Nature.
The findings come as the US government prepares to release a highly anticipated Unidentified Flying Object (UFO) report. The report by the Pentagon’s Unidentified Aerial Phenomena Task Force, which was set up to better understand the nature and origins of unknown planes, should not reveal or rule out evidence of alien antics.
Professor Beth Biller of the University of Edinburgh’s Institute for Astronomy, who was not involved in the nature study, said the work could change the way scientists approach Seti, the research of extraterrestrial life. “What struck me was how few stars within 100 parsecs could have seen an Earth in transit,” she said.
“The transit method requires very precise alignment between the transiting planet, its star, and the sun for a given planet to be detectable, so this result is not surprising. Now, I am curious as to which fraction of the stars in the Gaia Catalog of Nearby Stars have the right viewpoint to detect Earth via other methods of detecting exoplanets, such as the radial speed method or imaging. direct!