When the transiting exoplanet blocks the star light, part of the light will pass through the atmosphere. Energy and light interact with the planet’s molecules and atoms, and when the light reaches the astronomer’s telescope, scientists can determine whether it interacts with chemicals such as oxygen or methane.
Kaltenegger said that the combination of the two is the fingerprint of life.
“What’s really interesting is that people can see the earth from about 2 billion years [ago]Because oxygen accumulates in the atmosphere,” she said.
The idea of studying transit to find out if we are on the radar of other people is nothing new. Kaltenegger attributed most of her inspiration to a program developed by the SETI Research Institute in the 1960s to find extraterrestrial wisdom.
In 1960, a radio astronomer named Frank D. Drake was the first to try to detect Interplanetary radio transmission, Focusing on two stars 11 light-years away, their age is similar to our sun. Although that attempt was unsuccessful, since then, scientists and amateurs have continued to look for such signals.
But whether the signal we sent is passed is another matter entirely. In this new study, Kaltenegger and Faherty report that artificial radio waves have swept through the 75 nearest stars on their list.
Although humans have been emitting radio waves for about 100 years, this is nothing compared to the billions of years of planetary evolution on Earth.