Exoplanet Earth: From These 1,004 Stars, Earth Is A Transiting Exoplanet

KEY POINTS

Scientists identified 1,004 nearby stars from where the Earth can be seen using the transit method
Of these stars, the closest star was just 28 light years away from the sun
These stars could be hosting potentially habitable planets

Technology helped us detect thousands of exoplanets to date, but what if the observers in other exoplanets were looking for neighbors as well? In a new study, a pair of researchers identified over a thousand sun-like stars from where the Earth might be detectable as a transiting exoplanet.

Transiting exoplanets are extrasolar planets discovered using the transit method or by the dips in a star's light that may indicate the presence of an orbiting planet. The method also provides clues about a planet's atmosphere.

In the new study, researchers Lisa Kaltenegger of Cornell University and Joshua Pepper of Lehigh University looked at this method from the other way around. If observers from other systems are looking for exoplanets using the transit method, just like we are, which ones would see the Earth as a transiting exoplanet?

To answer the question, the researchers used NASA's Transiting Exoplanet Survey Satellite (TESS) Input Catalog and data from Gaia DR2. They found 1,004 main-sequence stars within 100 parsecs (326 light years) that were aligned with the Earth's ecliptic or plane of orbit around the sun in such a way that, to them, the Earth would be an exoplanet passing its host star.

In other words, from the vantage point of these 1,004 stars, the Earth is a transiting exoplanet.

Pale Blue Dot 2020 — Image: An updated version of the iconic 'Pale Blue Dot' image taken by NASA's Voyager 1 in 1990. The "pale blue dot" in the image is the Earth, as seen by the spacecraft from 3.4 billion miles away. NASA/JPL-Caltech

"If observers were out there searching, they would be able to see signs of a biosphere in the atmosphere of our Pale Blue Dot," Kaltenegger said in a news release from Cornell University. "And we can even see some of the brightest of these stars in our night sky without binoculars or telescopes."

Of these stars, the closest one is just 28 light years away from the sun.

"If we found a planet with a vibrant biosphere, we would get curious about whether or not someone is there looking at us too," Kaltenegger said in the news release.

"Maybe there's life out there in the Universe," Kaltenegger added in a video released by Cornell University. "Maybe they already spotted us."

According to the researchers, NASA's TESS, which is now in its extended mission, will also be searching for possible exoplanets in the ecliptic.

The study was published in the journal The Monthly Notices of the Royal Astronomical Society.