When humanity speeds up its search for alien life, we have to bear in mind that E.T. may even be looking for us, too.
A recent analysis allows that case by discovering more than 1,000 neighboring stars that are favorably placed for detecting life on Earth.
"If observers were out there searching [from planets orbiting these stars], they would be able to see signs of a biosphere in the atmosphere of our Pale Blue Dot," study lead author Lisa Kaltenegger, an associate professor of astronomy at Cornell and director of the university's Carl Sagan Institute, said in a statement.
"And we can even see some of the brightest of these stars in our night sky without binoculars or telescopes," Kaltenegger said.
Earthly Transit
Astronomers also discovered several of the more than 4,000 exoplanets discovered to date using the "transit process," which describes the minor brightness dips induced from the observer's viewpoint as an orbiting world passes the face of its host star. NASA's groundbreaking Kepler Space Telescope used this technique to considerable benefit and is currently being used by its replacement, the Transiting Exoplanet Survey Satellite (TESS).
Soon, experts may also be able to look for possible indicators of existence in several close transiting planets' atmospheres. This search would be one of the several activities performed by, for example, NASA's $9.8 billion James Webb Space Telescope, expected to be unveiled late next year. And there will also be future ground-based megascopes, including the Massive Magellan Telescope performing such work.
In the new research, Kaltenegger and co-author Joshua Pepper, an associate professor of physics at Lehigh University, found Earth to be the target rather than the source of a transiting planet survey.
The researchers analyzed the TESS and European star-mapping Gaia spacecraft databases, checking for stars within 100 parsecs (about 326 light-years) associated with the ecliptic, the plane orbiting Earth around the sun. To see the Planet cross the face of the sun, some adjustments are necessary.
This search turned up 1,004 qualifying main-sequence stars that fuse hydrogen into helium in their centers, like our sun. And in a recent analysis released online in the journal Monthly Notices of the Royal Astronomical Society: Letters, Kaltenegger and Pepper wrote that 508 of those stars "guarantee a least 10-hour-long observation of Earth's passage" around the face of the sun.
New tool to search for E.T.
The latest findings deal with stars only. Scientists do not know how many planets flagged by Kaltenegger and Pepper circle the 1,004 suns, let alone how many of these structures harbor worlds that, as we know, might be conducive to existence.
As exoplanet hunters like TESS continue their mission, those figures should come into sharper view. And in the meantime and the future, the current research will serve as a signpost for astrobiologists, Kaltenegger said.
She added experts had just created the star map of where they should look first if they are looking for intelligent life in the universe that could find us and might want to get in touch.
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