20 July, 2008

Sunday Sensational Science

I'll never forget the first time I saw Saturn through a backyard telescope. It was so tiny, and yet so perfect - the rings standing out with incredible clarity. It didn't even look real, and yet, I'd seen my neighbor, a professional astronomer at Lowell Observatory, point his ten inch telescope at the night sky and focus carefully before stepping back and letting the kids look at another world.

Saturn is a world unlike any other.

The Cassini Mission is proving that, and returning some spectacular photos of Saturn and its moons:

After an epic journey of seven years and 3.5 billion kilometres, the Cassini spacecraft entered Saturn orbit on 1 July 2004. The Cassini-Huygens mission is a $3 billion, 4-year tour of Saturn, its rings and many of its 40-odd known moons. No other spacecraft had been near the solar system's second largest planet since the Voyager flybys of the 1980s.

Three billion dollars buys you a lot of science. Serious science. No, really:

The most spectacular highlight of the mission so far is its visit to Titan, Saturn's largest moon. ESA's Huygens probe was released by Cassini and descended through the dense atmosphere of Titan in January 2005. It became the first probe to land on such a distant world.

Huygens discovered a strikingly Earth-like landscape of hills and branching valleys, though the peaks are ice and the intermittent rivers carry liquid methane. Cassini has also seen clouds and old shorelines, as well as evidence for deserts, an ice volcano and a possible lake of methane near the south pole. But there has been no sign of the methane seas or oceans once expected.

Scientists are loving Titan, but my fascination lies with the water vapor jets streaming from Enceladus:

On a previous, much closer pass by Enceladus, Cassini detected that the south pole of Enceladus is spewing out a vast plume of water vapour that stretches hundreds of kilometres from the moon's surface and keeps Saturn's E-ring topped up – but it has now captured the first images of this activity. On Sunday, 27 November, Cassini was positioned so that the Sun was behind the moon, causing one side of Enceladus to be illuminated as a fine crescent, with its volcanic plumes backlit.

Enceladus is only the third body in the solar system to show signs of active volcanism, besides Earth and Io, Jupiter's moon. Even though this volcanism is relatively gentle, planetary scientists cannot yet work out what is driving it. The new pictures could help by revealing the muzzle velocity of the moon's plumes.

Part of the fun of exploring the solar system is turning back for a look at home. Here we are, the tiniest of pale blue dots, shining between the rings of Saturn. We're another of the wandering stars. Someday, we may be able to get this perspective from a resort on Titan, sipping drinks and thinking of how far we've come.

Rather puts things in context, that.

I think the single most spectacular image, though, is Saturn eclipsing the Sun. This isn't an artist's interpretation, not a product of the imagination, but a photograph, enhanced just a bit to bring out the dramatic beauty of it. And if you look really closely, you'll see an infintesimal pale blue dot, shining inside the rings.

This is our bit of the Universe. Outstanding, isn't it?

1 comment:

Anonymous said...

The link for the lat image is incorrect. It should be http://ircamera.as.arizona.edu/NatSci102/NatSci102/lectures/saturn.htm