Scientists, among other communities we follow, make us smile when they speak in a language we can understand (those of us who are not scientists, which is most of us on this site). We have had occasion in the past to point to the famed scientist and former Cornell University professor Carl Sagan, and now Robert Krulwich shares this video on one of his Wonders posts (after clicking through, scroll down):
…Looking at this, Carl Sagan thought, first, how small we look, how small we are — which inspired him to write his eloquent Pale Blue Dot meditation, which, if you haven’t read it lately, take a minute and a half to look at this short version gorgeously animated by Joel Somerfield at Order, a British design studio. Carl Sagan himself is narrating.
Our smallness, our alone-ness impressed Sagan, but so did our noisy colorfulness. We emit radio waves and TV signals. We have technology. We are blue in our watery parts, reddish on our land parts (because the chlorophyll in our plants “fluoresces” red light back into space). Which gave Sagan an idea.
Imagine you are sweeping through a solar system, looking for a place, any place that might harbor some sign of life, and there, in the blackness, you see a dot of light, a little pinprick shining back at you. Could you, from a distance, learn if there is life there? Are there telltale signs?
Check Out This Place Called ‘Earth’
Sagan imagined four traits that he thought would be strong indicators of life: the persistent presence of methane, an unusual proportion of oxygen in the atmosphere (both often produced by life), a reddish coloring on land, (because of the chlorophyll) and radio waves. If the planet is broadcasting, somebody down there must be talking (and tinkering).
Then he proposed an experiment — the first ever life-sensing test. He knew, back in 1990, that another NASA spacecraft, Galileo, was zipping past Earth on its way to Jupiter, so he asked NASA to turn to the probe to earth to see if it could pick up the four traits. Yup, yup, yup and yup. Methane, oxygen, reddish tones and radio waves, all of them, of course, were there.
Then, because he wanted this to be the world’s first-ever controlled experiment in astrobiological sensing, he asked that the probe be turned to the moon