Planetary science: Caught in the act

We may be seeing some of the Solar System’s most striking objects during rare moments of glory.

Maggie McKee
30 January 2013

Ever since Copernicus evicted Earth from its privileged spot at the centre of the Solar System, researchers have embraced the idea that there is nothing special about our time and place in the Universe. What observers see now, they presume, has been going on for billions of years — and will continue for eons to come.

But observations of the distant reaches of the Solar System made in the past few years are challenging that concept. The most active bodies out there — Jupiter’s moon Io and Saturn’s moons Enceladus and Titan — may be putting on limited-run shows that humans are lucky to witness. Saturn’s brilliant rings, too, might have appeared relatively recently, and could grow dingy over time. Some such proposals make planetary researchers uncomfortable, because it is statistically unlikely that humans would catch any one object engaged in unusual activity — let alone several.

The proposals also go against the grain of one of geology’s founding principles: uniformitarianism, which states that planets are shaped by gradual, ongoing processes. “Geologists like things to be the same as they ever were,” says Jeff Moore, a planetary scientist at the NASA Ames Research Center in Moffett Field, California. The unchanging world is “philosophically comforting because you don’t have to assume you’re living in special times”, he says.

But on occasion, the available evidence forces researchers out of their comfort zone. Here, Nature looks at some of the frozen worlds that may be putting on an unusual spectacle.

Read more: Planetary science: Caught in the act : Nature News & Comment.

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