Scientists have identified thousands of other planetary systems where alien life can see Earth.
Scientists consider that nearby star systems are relatively close in cosmological terms, and have been positioned to be able to watch our planet transit in front of the sun.
Planets around those stars will be able to see Earth, and see if they hold life, and they probably did.
Just as we watch other stars for planets passing in front of them, and use this information to understand their atmosphere and whether they are able to support alien life, aliens will be able to do the same for Earth.
“From an exoplanet standpoint, we’re extraterrestrials,” said Lisa Kaltenegger, professor of astronomy and director of the Carl Sagan Institute in Cornell University’s College of Arts and Sciences.
And she continued, “We wanted to know which stars have the best point to see Earth, because they block sunlight.” “And because the stars are moving in our dynamic universe, the vantage point is gained and lost.”
In the new research, scientists identified a total of 2,034 star systems, all within 326 light-years. Of these, 1,715 would have observed Earth since human civilization began in the last few millennia – the rest will be able to see us in the next 5,000 years.
Of those stars, 75 are 100 light-years away from us – that’s close enough that human-created radio waves that can reach them.