The other day, planetary scientists came to very unusual conclusions. The fact is that many earth-like planets far beyond our solar system have all the conditions for direct observation of our planet Earth, which means that aliens may already know about our existence.
The hunt for alien life so far has focused on our closest neighbors in the solar system and planets orbiting stars far beyond our reach. Since the first exoplanet was discovered in 1992, astronomers have found that there are more planets than stars dotting our night sky.
Missions such as NASA Kepler and TESS have discovered thousands of interesting worlds that can be studied for biosignatures – chemical elements that could indicate the existence of life.
A duo of astronomers in the United States have suggested that if we have the means to see these worlds, potential alien civilizations will have the means to see us. And if somewhere out there, among the stars there is developed life, most likely we have already been noticed.
Lisa Kaltenegger, associate professor and director of the Carl Sagan Institute at Cornell University, and Joshua Pepper, associate professor of physics at Lehigh University in Pennsylvania, have identified 1004 nearby stars similar to our Sun.
These stars can illuminate earth-like planets located in the so-called habitable zone, where conditions are created for the existence of liquid water on the surface.
All of these stars are within 300 light-years of Earth, which means they are close enough for us to study the planets in their orbit for biosignatures. The planets in this catalog also allow Earth observation, which means that aliens can also scan our world for signs of life.
Professor Kaltenegger shared his observations:
'Let's change our vantage point and move to other stars. We ask, from what point of view can other observers find the Earth as a transit planet? If intelligent alien observers were searching, they could easily see signs of the biosphere in the atmosphere of our pale blue dot. They could even see some of the brightest objects in our system without binoculars or telescopes. '
So far, the most popular way of detecting other planets is by tracking transits. Transiting planets are worlds that pass in front of the star in the field of view of the observer.
Transits also allow astronomers to catch a glimpse of the planet's atmosphere, which may provide clues about what is happening on the surface. Astronomers' ideas were presented this week in the Royal Astronomical Society's Monthly Notices.
