“From the point of view of the exoplanets, we are the aliens”


Scientists have identified over 2,000 star systems with the correct position to be able to discover our Earth. It can help us in the pursuit of extraterrestrial life.

Astronomers have used information from the European space agency ESA’s Gaia eDR3 catalog to determine which stars have entered and left the so-called “Earth Transit Zone”. This transit zone is a special area in space from which extraterrestrial life could discover the earth, by watching our planet pass in front of the sun.

Their conclusion is that just over 1,700 star systems located within 100 parsecs (326 light-years) from Earth have been in the right position for the past 5,000 years for potential life on nearby exoplanets to have been able to detect our planet.

A further 319 will end up in such a situation within the next 5,000 years, according to researchers at, among others, American Cornell University.

– From the point of view of the exoplanets, we are the aliens, says astronomy professor Lisa Kaltenegger at Cornell’s Carl Sagan Institute in a statement.

A total of 75 identified objects have been in the right zone since we started with commercial radio stations on Earth, which have sent out signals into space.

Seven of the just over 2,000 star systems that have been identified have previously been found to have exoplanets.

1.8 times larger than Earth

The Ross 128 system is about 11 light-years away and has an exoplanet just over 1.8 times larger than our own Earth. Scientists note that potential life on this planet could have discovered our earth in 2,158 years. However, that possibility ceased about 900 years ago, when conditions were no longer as favorable.

Potential life on the exoplanets around the Trappist 1 system, which is 45 light-years away, will not be able to discover the Earth until 1642 years at the earliest. Only then do they end up in the earth’s transit zone.

– Our analysis shows that even the nearest stars in general for over 1,000 years are in an advantageous position where they can see the earth’s transit, says astrophysicist Jackie Faherty at the American Museum of Natural History in a comment.

She adds that if we then assume that the opposite is true, we also have a “healthy timeline” for other civilizations to be able to identify the earth as an interesting planet.

Studien “Past, present and future stars that can see Earth as a transiting exoplanet” has been published in the scientific journal Nature.


Source: Nyteknik – Senaste nytt by www.nyteknik.se.

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