Carl Sagan, everyone's favorite late astronomer, would have been 78 today. We can't think of anyone who inspired so many people to love science and the universe than good old Sagan. This year, we're looking back to an interview with the scientist that appeared in our September 1972 issue. At the time, he was really stoked about Mars.

 

At the time of publishing, the scientific community was trying to figure out just what Mars was like, and photos from the Mariner 9, a NASA space orbiter, had recently revealed that the red planet was completely different than we thought. The scientific community decided that Mars was a dead planet, but the photos showed evidence of high winds, dust storms, massive geological craters that would rival the Grand Canyon, and the possibility of running water. PopSci turned to Carl Sagan to explain these exciting new findings.

 

Sagan told us the Mariner 9 photo results he found most significant were evidence of changes due to windblown dust, evidence of volcanic activity, evidence of running water and recession of polar caps. These findings are now coming full circle as the Curiosity rover gets up close and personal with the Martian terrain. It only took some 40 years.