Eye of the Beholder

The Viking Orbiter’s picture of a hill in the Cydonia region
on Mars that sparked popular speculation of a
monument-building Martian civilization.
Credit: NASA/Viking

When I heard the news flash that came out in early June about the alleged discovery of standing puddles of water on Mars, a part of me was immediately skeptical. Considering how cold and thin Mars' atmosphere is known to be, standing liquid water simply cannot persist on the surface; it would either evaporate or quickly freeze-- something I've known since my earliest physics classes.

But, I have to admit, a part of me tried to imagine how there possibly might be puddles on Mars' surface-- like, maybe such puddles could be supplied by a warm spring of some kind, right? It wasn't the scientific side of me that tried to make this square peg fit in the round hole; it was the part of me that simply wants to find liquid water there...

As it turned out, no puddles were found on Mars; the claim, controversy, and retraction, which all occurred at warp speed, were a temporary blip on the radar screen of space exploration. Taken out of context, out of the bigger picture, images can easily mislead.

History is well-furnished with accounts of people who made an observation of this or that, interpreted what they saw-- and turned out to be wrong. The history of astronomy is not an exception.

While astronomers are trained to be objective observers and careful experimenters, and not to jump to conclusions, being human, it's hard not to guess at the nature of what is seen, not to preconceive notions to some extent, and not to use our imaginations to stretch a bit further than the observational evidence at hand.

When telescopes were first turned to the skies, in 1609, astronomers could see more than before, but also had more to speculate about. Upon viewing Saturn through his telescope, Galileo described seeing what looked like "jug handles" on either side of the planet-- and while he probably never thought they were actual handles sticking to the planet, he did suggest they might be two large moons. What he saw, of course, were Saturn’s now-famous rings.

When astronomers first observed galaxies, they were called nebulas (literally, ''clouds'') and believed to be merely composed of gas. The ''spiral nebulas'' (''nebulae'' for the sticklers of Latin grammar) turned out to be composed of billions of stars, not just gas.

Planetary nebulas -- shells of gas sloughed off by certain dying stars -- were so named because of their planet-like appearance in early, low-powered telescopes (although they were not actually believed to be planets).

Fast forwarding a bit, the first close-up pictures of Mars, taken in 1965 by the Mariner 4 spacecraft, provided just enough visual evidence to characterize Mars as a barren, cratered world not unlike our Moon-- a far cry from the colorful world we know today.

And who can forget the infamous ''face'' on Mars?

I get plenty of phone calls and emails from people reporting seeing something completely astonishing and unique in the sky-- things that turn out to be known objects, like Venus or Sirius or the like. And, sometimes, it's a true uphill battle to convince an eyewitness to the inexplicable that what they witnessed was, in fact... well... explicable.

Benjamin Burress is a staff astronomer at The Chabot Space & Science Center in Oakland, CA.