A new study, which stars can see earth as a transiting exoplanet, published on October 20, 2020 says that more than 1,000 nearby stars are positioned for detecting life on Earth. These stars may have Earth-like planets in their own habitable zones and have a clear line of sight to observe chemical traces of life on Earth. There is, therefore, a possibility that just as we humans on planet Earth are scrambling to search for alien life, aliens might also be trying to spot us!
So far, astronomers have detected more than 3,000 transiting exoplanets. In fact, Nasa’s Transiting Exoplanet Survey Satellite (TESS) mission has already searched about 74 per cent of the sky in its two-year primary mission for transiting extrasolar planets, including potentially habitable worlds orbiting the closest and brightest stars.
Exoplanet is a planet which orbits a star outside our solar system.
Lisa Kaltenegger, the study lead and an associate professor of astronomy at Cornell and director of the university’s Carl Sagan Institute, said that if aliens from nearby stars were actually searching for life in the universe, they would see signs of the biosphere on planet Earth. Some of these stars, she said, can be seen from Earth even without telescopes or binoculars.
For this study, the scientists scrutinised the datasets of NASA’s Transiting Exoplanet Survey Satellite (TESS) and Europe’s star-mapping Gaia spacecraft, looking for stars within 100 parsecs (about 326 light-years) that are aligned with the ecliptic, the plane of Earth’s orbit around the Sun. This search turned up 1,004 qualifying main-sequence stars-stars that fuse hydrogen into helium in their cores. And 508 of those stars guarantee a minimum 10-hour-long observation of Earth’s transit across the Sun’s face.
So far, astronomers have found more than 4,000 exoplanets, most of them through the ‘transit method’, which detects the tiny brightness dips caused when an orbiting world crosses its host star’s face from the observer’s vantage point.
These stars are all within 326 light-years of Earth. The closest star is at a distance of only 8.5 pc-about 28 light-years-from our Sun.
So, according to researchers, if we are looking for intelligent life in the universe that could find us, the star map can provide the first clue.
Courtesy: India Today, Space.com