Astronomers searching the cosmos for signs of life are getting curious about who might be looking back. Of the hundreds of billions of stars in our galaxy, astronomers have pinpointed 1,715 nearby systems where their alien counterparts might have been able to detect Earth at some point in the last 5,000 years by observing our planet traveling in front of the sun, the Guardian reports. Some 1,402 of them can see us now, and hundreds more within 100 parsecs—326 light years—of us will have what researchers call the "cosmic front seat" in the 5,000 years to come. The researchers, whose study is published in the journal Nature, say there are at least 29 potentially habitable planets whose possible inhabitants could have intercepted radio and TV broadcasts from Earth or observed Earth's transit across the sun.
The transit method—detecting a slight dimming of a star as a planet passes between it and the observer—has spotted around 70% of the more than 4,000 exoplanets researchers have found in recent decades. "We asked, 'Who would we be the aliens for if somebody else was looking?'" lead study author Lisa Kaltenegger, professor of astronomy and director of the Carl Sagan Institute at Cornell University in New York, tells Forbes. "There is this tiny sliver in the sky where other star systems have a cosmic front seat to find Earth as a transiting planet." She says that when the James Webb Space Telescope is launched later this year, searches for more planets that could potentially see us should be a priority. (Read more extraterrestrial life stories.)