Astronomers announce alien I.D. chart
The artist’s image above depicts the Earth 3.9 billion years ago. The days were shorter and the sun was dimmer, shining as a red orb through an orange brick–colored sky. A single ocean is thought to have covered Earth then, colored muddy brown: a place that absorbed incoming meteors and comets bombarding the early Earth. At this time in Earth’s history, Earth is thought by scientists to have possessed a turbulent, steamy atmosphere composed mostly of nitrogen, carbon dioxide and hydrogen sulfide.
And so begins a description of Earth’s past by astronomers Lisa Kaltenegger and Wesley Traub.
Kaltenegger and Traub have developed what they are calling an “alien I.D. chart” that will provide “the signposts astronomers will look for when examining truly Earth–like worlds” for signs of alien life.
They’re basing their chart on geologic records indicating that Earth’s atmosphere has changed dramatically during the past 4.5 billion years, in part because of life forms developing on our planet.
Mapping what gases comprised Earth’s atmosphere during its history, Kaltenegger and Traub propose that by looking for similar atmospheric compositions on other worlds, scientists will be able to determine if that planet has life on it, and if so, that life’s evolutionary stage.
Kaltenegger explains, “As daunting as this challenge sounds, I do believe in the next few decades we will know whether or not our little blue world is all alone in the universe or if there are neighbors out there waiting to meet us.”
Read more: Astronomers Reveal First Alien I.D. Chart from spaceref.com .
I think we’re going to find out a lot about ourselves if and when we find life elsewhere. Although I do admit that I sometimes have a “War of the Worlds” feeling towards alien contact.
In that same vein, it’s interesting that these scientists have a working assumption that life out there would change its planet in ways that we have changed ours.
This reminds me of a conversation I had a while back with Maggie Turnbull of the Carnegie Inst., where she explained the human bias in searching for intelligence outside our solar system.
“We want to be as open minded as possible when we’re looking for life in the universe. But for SETI, and for Terrestrial Planet Finder, as the very beginning stages for this search for life on other planets, we’re starting with what we know.
And, while we want to leave room in our target lists for life that is unlike what we know on Earth, for the moment we’re looking for the things that we would be able to recognize.
In other words, we’re looking for ourselves among the stars.” – Maggie Turnbull to Earth & Sky December 2005.
I wonder if aliens looking at earth from far away would be able to tell that we’re here.
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