Post by MCDemuth on Jun 25, 2021 2:11:20 GMT
Can ET See Us? Study Finds Many Stars With Prime Earth View
06/23/2021 05:05 pm ET
Astronomers took a technique used to look for life on other planets and flipped it around — so instead of looking to see what’s out there, they tried to see what places could see us.
There’s a lot.
Astronomers calculated that 1,715 stars in our galactic neighborhood — and hundreds of probable Earth-like planets circling those stars — have had an unobstructed view of Earth during human civilization, according to a study Wednesday in the journal Nature.
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One way humans look for potentially habitable planets is by watching them as they cross in front of the star they are orbiting, which dims the stars’ light slightly. Kaltenegger and astrophysicist Jacqueline Faherty of the American Museum of Natural History used the European Space Agency’s Gaia space telescope to turn that around, looking to see what star systems could watch Earth as it passes in front of the sun.
They looked at the 331,312 stars within 326 light-years of Earth. One light-year is 5.9 trillion miles. The angle to see Earth pass in front of the sun is so small that only the 1,715 could see Earth at some point in the last 5,000 years, including 313 that no longer can see us because we’ve moved out of view.
Another 319 stars will be able to see Earth in the next 5,000 years, including a few star systems where scientists have already spotted Earth-like planets, prime candidates for contact. That brings the total to more than 2,000 star systems with an Earth view.
The closest star on Kaltenegger’s list is the red dwarf star Wolf 359, which is 7.9 light-years away. It’s been able to see us since the disco era of the mid 1970s.
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Carnegie Institution for Science planetary scientist Alan Boss, who wasn’t part of the study, called it “provocative.” He said in addition to viewing Earth moving in front of the star, space telescopes nearby could spot us even if the cosmic geometry is wrong: “So intelligent civilizations who build space telescopes could be studying us right now.”
So why haven’t we heard from them?
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What’s exciting about the study is that it tells scientists “where to point our instruments,” said outside astronomer Seth Shostak of the SETI Institute that searches for extraterrestrial intelligence. “You might know where to look for the aliens!”
Read More Here:
www.huffpost.com/entry/et-prime-view-of-earth_n_60d3a052e4b06005129e329a
Interesting Idea... I never really thought about if Aliens could actually detect Earth, and how they would accomplish it...
And, yeah, we might want to focus on listening for Alien signals from star systems that can actually detect Earth... They're not likely to randomly send out signals to star systems where they don't know if there are any planets there or not.
