Astronomers have discovered thousands of solar systems where alien life could see our planet. The nearby star systems are relatively close when talking in astronomical terms, and are positioned in a way that they could watch Earth when it crosses in front of the Sun.
Planets around those stars can watch Earth, and understand whether it fosters life, or might have already done so. Just how scientists on Earth watch other stars for planets passing in front of them and use the data to study their atmospheres, extraterrestrials could do the same for Earth.
75 stars in close proximity
“From the exoplanets’ point-of-view, we are the aliens,” said Lisa Kaltenegger, professor of astronomy in the College of Arts and Sciences. “We wanted to know which stars have the right vantage point to see Earth, as it blocks the Sun’s light,” she said. “And because stars move in our dynamic cosmos, this vantage point is gained and lost.”
In the new study, scientists found 2,034 new star systems, all located within 326 light-years. 1,717 of those could have spotted our planet since human civilization started in the last few thousand years – the rest could see in the coming 5,000 years. 75 of those stars are within 100 light-years of Earth, which is close enough to experience radio waves created by human beings.
The right place to observe Earth
The stars fall into different categories, and some of them have already been closely studies, while others are yet to be studied. Astronomers have enough data to determine how many of the stars have rocky planets orbiting them. They estimate there could 29 potentially habitable worlds that are positioned in a way that they can see Earth flying past the Sun, and are close enough to detect radio waves from Earth.
The research has used data from the Gaia database that has a catalog of astronomical objects that are observed within 300 light-years of the Sun. By combining the information, the team was able to figure out the right place to see Earth. The new study has been published in the journal Nature.
