Astronomers have pinpointed more than 2,000 stars from where, in the not-too-distant past or future, Earth can occasionally be detected transiting across the face of the Sun.
If there are aliens living on planets around those stars, with at least a similar level of technological advancement to our own species, then they would theoretically be able to spot us. They could even have observed as the amount of carbon dioxide in Earth’s atmosphere increased over the past several hundred years, since the industrial revolution.
The work, offers a new way of thinking about the search for extraterrestrial life, says Lisa Kaltenegger, an astronomer at Cornell University in Ithaca, New York, who led the analysis. “Who has the cosmic front seat to see us?” she asks. “For whom would we be the aliens?”
Those aliens would be the natural choice for Earthlings to look for, say the scientists — because they may have already had a chance to spot us, and thus might be primed to be ready for communications from Earth.
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