Astronomers Identify The Star Systems That Could Be Watching Earth From Space
If there were alien civilizations in other star systems, would they be able to detect our presence here on Earth? This is a question that could lead us to new ways to search for signs of extraterrestrial intelligence, but not one that is necessarily easy to answer.
Nevertheless, a team of astronomers has identified 2,034 star systems within 100 parsecs (326 light-years) of Earth that would have the right vantage point to detect Earth life signs as our home planet orbits the Sun.
"From the exoplanets' point of view, we are the aliens," said astronomer Lisa Kaltenegger of Cornell University's Carl Sagan Institute.
Using data from the Gaia space observatory - an ongoing project to map the Milky Way in three dimensions with the highest precision yet - Kaltenegger and her colleagues sought to determine if any alien civilizations out there could find humanity with the tools we use to find exoplanets.
We have several of these, but the most fruitful technique is what we call the transit method. When an exoplanet orbits a star, if that orbit is aligned just right, it will pass between us and its host star, known as a transit. This creates a very specific light curve signature as the starlight dims and brightens fractionally due to the exoplanet's transit.
