Astronomers have shortlisted nearby star systems, where any “curious observer” on orbiting planets would be well placed to discover life on Earth.
They have identified 1,715 star systems in our cosmic neighborhood from which aliens can “discover” the Earth in the past 5,000 years by watching it “cross” the face of the Sun.
Of those in the right position to observe Earth transits, 46 star systems are close enough for their planets to intercept a clear signal of human presence — radio and television broadcasts that began nearly 100 years ago, according to a study published in the scientific journal Nature.
They note that 29 potentially habitable planets are well positioned to watch Earth transits and hear those signals.
In addition to 1,715, astronomers have identified 319 other stars that are in a useful position for observing our planet in the next 5,000 years.
“If there were aliens living on planets around these stars, at a technical level at least similar to our own, they would theoretically be able to locate us. They have even observed an increase in the amount of carbon dioxide in the Earth’s atmosphere in hundreds of years, since the industrial revolution,” As the journal Nature says in a review of the study.
The data allows a new look at extraterrestrial life, says the author who led the research, Lisa Kaltenegger, an astronomer at Cornell University in Ithaca, New York (US).
“The debate about whether or not we should send an active signal or try to hide our presence has always existed.”
According to her, Earthlings looking for signs of extraterrestrial life should focus their efforts on these areas – because if there was advanced alien life out there, these civilizations would be more willing to communicate with Earth, assuming they marked our place before.
“In the search for life in the universe, transiting planets are currently our best targets. With thousands already discovered, our search is ushering in a new era of discovery with large telescopes that will look for signs of ‘life’ in the atmospheres of transiting worlds.”, say the authors of the article titled Past, present, and future stars that can see Earth as an exoplanet in transit.
“Observations from these stars began recently.”
Here we report that 1,715 stars are within 100 parsecs [uma medida de distância] They are in the right place to see life on Earth in transit since early human civilization (about 5,000 years ago), with an additional 319 stars entering this particular view in the next 5,000 years.”
Scientists shed light on the planet Ross-128, which saw the Earth pass in front of the Sun in the past. Two more planets – the star Teegarden and Trappist-1 – will be able to observe the transit of the Earth in 29 and 1642 years, respectively.
Scientists believe that Earth’s communications waves have passed through 75 stars.
Scientists’ analysis shows that even the closest stars often spend more than a thousand years in a privileged location where they can see Earth transits. So one might assume that the opposite is also true: that these planets have a window of a thousand years to see us.
If there was advanced life, or at least the same degree of technology as Earth, this would allow these civilizations to define Earth as a planet with life.
This discovery was made possible thanks to the European Space Agency’s Gaia space observatory, which has compiled the best 3D star map ever. Scientists say the observatory has “revolutionized” astronomers’ understanding of neighboring solar systems.
To Britain’s Guardian newspaper, Professor Beth Beller, from the Institute of Astronomy at the University of Edinburgh, Scotland (UK), who was not involved in the research published in Nature, said the work could change the way scientists approach research. for life outside planet earth.
“What was so impressive to me was that so few stars in 100 parsecs could see the Earth in transit,” she told The Guardian.
Astronomers and science fiction writers have speculated that civilizations might attempt to signal their existence by building artificial “giant structures” that pass in front of their stars, briefly dimming their light.
Some believe humanity should be planning something similar 29 years from now, when perhaps the eyes of the Trappist-1 system will be looking in our direction.
“Maybe we should consider installing a transient giant structure for them to observe,” Rene Heller, an astrophysicist at the Max Planck Institute for Solar System Research in Göttingen, Germany, told Nature.