More than 4,500 exoplanets have been discovered so far, with only a small portion thought to have the properties to contain life. A new study suggests that some of those planets and any extraterrestrial life that lives on them can see us too.
The research, published in the scientific journal Monthly Notices of the Royal Astronomical Society, has identified 1,004 stars that are similar to our sun that may have Earth-like planets in their orbit. These star systems have a “direct line of sight to observe Earth’s biological qualities from far, far away,” according to a statement accompanying the research.
“Let’s reverse the viewpoint to that of other stars and ask from which vantage point other observers could find Earth as a transiting planet,” Lisa Kaltenegger, associate professor of astronomy and director of the Carl Sagan Institute at Cornell University, said in the statement.
“If observers were out there searching, they would be able to see signs of a biosphere in the atmosphere of our Pale Blue Dot,” Kaltenegger added.
Sagan, one of the world’s most famous astronomers, was instrumental in the “Pale Blue Dot” photo taken by NASA’s Voyager 1 spacecraft in February 1990, looking at Earth from more than 3.7 billion miles away.
The findings, while thought-provoking, are limited by the amount of time each of the star systems can observe Earth, the researchers noted. Only 508 of them are able to “guarantee a minimum 10 [hour] long observation of Earth’s transit,” the researchers wrote in the study.
The study’s co-author, Joshua Pepper, said “only a very small fraction” of exoplanets could align just right so those on Earth could see their transit, but all of the 1,004 identified in the paper can see us, potentially “calling their attention.”
It’s also possible the life on these planets could exist for billions of years, given the properties that they are believed to possess, a sign they need additional study.
These planets have been observed due to transit observations, or when an object crosses in front of a star, dimming the star, thus allowing astronomers to see it. This type of observation will be expanded when NASA launches its James Webb Space Telescope in October 2021. If an extraterrestrial civilization had its own advanced equipment, similar to the JWST, they may be able to see us as well.
“If we found a planet with a vibrant biosphere, we would get curious about whether or not someone is there looking at us too,” Kaltenegger explained. “If we’re looking for intelligent life in the universe, that could find us and might want to get in touch. We’ve just created the star map of where we should look first.”
In June, a separate group of researchers suggested there are 36 “intelligent civilizations” in the Milky Way galaxy, a calculation the experts have dubbed “the Astrobiological Copernican Limit.”
A separate study published in mid-May suggested that not only is the “universe teeming with life,” but that it’s “the favored bet.”