If alien worlds are detecting Earth from light years away, they are finding a gassy rock that has plenty of clues of life on it, researchers told National Geographic for an article on Monday.
Because of the presence of its oxygen, Earth's secret has been out of the bag for billions of years, they said.
"The presence of life on Earth has been fairly obvious for the last four billion years to anyone who could build a big telescope," Joshua Krissansen-Totten, a doctoral student in earth and space sciences at the University of Washington, told National Geographic.
"If there was anything nasty out there, then they would have extinguished life on Earth long ago. I think we are safe inviting them over to visit and exchange notes on the cosmos," Krissansen-Totten added.
While aliens may or may not be looking at Earth, NASA's Kepler Space Telescope launched in 2009 has been looking back.
At least 2,335 planets have been confirmed out there as of 2017, according to Space.com, as the telescope tries to find planets in what NASA calls the habitable zone – those planets a certain distance from a star that allows it to have liquid water on the surface. Like the relationship between the Earth and its star, the sun.
While oxygen can be a giveaway to life's presence, Stephanie Olson, an astrobiologist at the University of California, Riverside, told National Geographic that alien scientists would be scouring the Earth for a few more clues.
"We have discovered several ways in which O2 can accumulate in the absence of life," Olson told the magazine. "High levels of O2, or the processes culminating in high levels of O2, may actually preclude the emergence of life on some planets."
Alien astronomers would be looking for nitrogen, carbon dioxide, nitrous oxide, and methane in the atmosphere to feel pretty confident that life exists on Earth, National Geographic explained.
Interstellar scientists would find that Earth orbits a stable star, which has allowed the planet to grow life mostly uninterrupted.
They also could pick up on our radio waves, but they would have to be as close as 590 trillion miles to actually listen in, National Geographic said.
And while humans have a lot of hardware orbiting the Earth, like the International Space Station and satellites, National Geographic said those would be hard to pick up by long-distance, space-searching telescopes.
© 2025 Newsmax. All rights reserved.