Since its launch in 2009, NASA’s Kepler spacecraft has been hunting for habitable exoplanets. To do this, the spacecraft utilizes the transit method of planet finding. It hones its sights on a distant star, and watches as a planet passes in front of the star. Based on the change in the star’s brightness, scientists are able to tell the planet’s size, and based on the time between transits, they can also estimate the orbit size and temperature.
Researchers from McMaster Univ. and the Max Planck Institute for Solar System Research are suggesting that extraterrestrials may utilize the same methods in their own search for “extraterrestrial life.”
Publishing in Astrobiology, René Heller and Ralph Pudritz suggest that humans should listen to Earth’s transit zone to see if extraterrestrials have sent broadcasts to the thin area in an attempt to contact humanity.
“It’s impossible to predict whether extraterrestrials use the same observational techniques as we do,” said Heller in a prepared statement. “But they will have to deal with the same physical principles as we do, and Earth’s solar transits are an obvious method to detect us.”
According to Nature News, the researchers used a catalogue of stars from data taken on the Hipparcos satellite, which operated between 1989 and 1993. From that data amalgamation, the researchers found 82 sun-like stars within 1,000 parsecs of Earth, a distance from which Earth would visible as it transited in front of the sun. They expanded the number of stars to 10,000 candidates, simply due to the fact that not all stars in the region have been discovered, Nature News reported.
“If any of these planets host intelligent observers, they could have identified Earth as a habitable, even as a living world long ago and we could be receiving their broadcasts today,” the researchers wrote.
From Earth, there are about 100,000 potential stars that could host habitable life. The number is gleaned from the modern radio telescope technology. Since launching, Kepler has confirmed the existence of 1,039 exoplanets.
Heller and Pudritz suggested that monitoring Earth’s transit zone for broadcast signals could dovetail well with the $100 million Breakthrough Listen Initiative. The initiative, supported by Stephen Hawking, aims to use the world’s largest telescope to scour the nearest million stars, the inner region and galactic plane of the Milky Way galaxy, and the nearest 100 galaxies for extraterrestrial life.