Scientists have found 2034 star systems from which life on Earth can be seen: some of them are located within a hundred light years and can not only see the transits of the Earth, but also register radio emission from it.
Astronomers at Cornell University have compiled a list of 2,034 star systems, the alleged inhabitants of which can see the passage of the Earth across the disk of the Sun: they are within 100 parsecs (326 light-years).
In order to understand what the Earth looks like from different stars, scientists used the transit method. Transit photometry is a method for detecting exoplanets based on observations of the planet’s passage against the background of a star. Allows you to determine the size, and in combination with the Doppler method – the density of the planets.
As a result, it turned out that over the past 5 thousand years the Earth was and remains noticeable from 1715 star systems, and in the next 5000 years it will become noticeable from another 319 systems. You can see not only the Earth, but also the presence of oxygen, a complex organic matter, which with a high probability indicates the presence of life.
In addition, the inhabitants of 75 star systems on this list could also potentially capture Earth’s radio transmissions, if they have the technology to capture them.
Even the stars closest to the Sun spend more than a thousand years in an advantageous position (they can see the transit of the Earth along the Sun), which gives hypothetical extraterrestrial intelligent beings a long time to identify the Earth as an interesting planet.