Newspaper article The Christian Science Monitor

Water, Water Everywhere in Our Solar System's Moons

Newspaper article The Christian Science Monitor

Water, Water Everywhere in Our Solar System's Moons

Article excerpt

The confirmation of a subterranean ocean underneath the icy surface of Jupiter's moon Ganymede is the latest thread in a mounting body of evidence that water - and by theoretical extension, life - in our solar system need not be relegated solely to the narrow neither too hot nor too cold orbit known as the Goldilocks zone inhabited by Earth.

With this confirmation, announced Thursday by NASA, Ganymede joins the ranks of two other moons that lie beyond the reach of the sun's warmth and are believed to host underground reservoirs of liquid water. Evidence of similar oceans has been detected on Europa, another of Jupiter's moons, and Enceledus, which orbits Saturn.

This growing body of evidence that one of the key ingredients for life exists outside the range that was once considered to be the solar system's only hospitable zone has prompted astronomers to completely rethink where and how they look for signs of life elsewhere in the solar system.

"One of the things that we have learned in the last few decades is that life as we know it is not as we knew it," says Nick Schneider, professor at the University of Colorado's Department of Astrophysical and Planetary Science in Boulder, Colo.

While the quest for evidence of microbial life in the solar system may seem inconsequential to Earthlings, discovery of any form of life, however small, could hold profound clues about the origin of life on our own planet, says Dr. Schneider, who was not involved in the Ganymede research, but serves as the instrument lead on the Imaging UltraViolet Spectrograph for NASA's MAVEN mission to Mars.

"I think that people will really come to accept this as the most profound question that we can ask," he says.

Astronomers first began to theorize that factors other than proximity to the sun could raise temperatures on other worlds to levels conducive to liquid water even before the first Voyager flybys around the Jupiter system in the 1980s, says planetary scientist Heidi Hammel, the executive vice president of the Association of Universities for Research in Astronomy (AURA) in Washington, D.C.

"What we're learning is that the sun and its warmth isn't the only way to get warmth in the solar system and we've been thinking that for some time," Dr. Hammel says. "However, there's a difference between having a theory about something and having evidence that the model is correct."

Evidence confirming the presence of a subterranean ocean on Ganymede comes courtesy of NASA's Hubble telescope and a new approach to analyzing its imagery pioneered by Joachim Saur, professor of geophysics at University of Cologne in Germany.

Dr. Saur's approach focused on Ganymede's aurorae, which are created by the mingling of Jupiter' magnetic field with that of the moon's. Ganymede - the largest moon in the solar system - is the only satellite large enough to house its own magnetic field. …

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