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Hey, Nice Ring! - Saturn
updated: Jul 13, 2013, 11:00 AM
By Chuck McPartlin
Well placed for viewing in Santa Barbara skies during spring and well into summer is
the coolest planet in our solar system - Saturn. It's currently in the constellation
Virgo, down in her feet. There is only one bright star in Virgo, a blue star called
Spica. The Greeks saw Virgo as Ceres, the goddess of agriculture, and Spica represented
a spike of wheat held in her hand. On Monday evening, July 15, the first quarter Moon
will be just below Spica, and Saturn will be off to their left and up (northeast).
To put things in perspective, the Moon will be 233,600 miles away. At the speed of light,
that's 1.25 seconds in the past. Saturn will be 892 million miles away, almost an hour and
20 minutes ago. Spica is 1,578 trillion miles away, or just over 260 light years distant.
Through even a small telescope, with at least 30x of magnification, Saturn is just about
the most astounding thing you can look at. If our upper atmosphere is not roiled up by
the jet stream, Saturn looks so perfect, it seems fake. Don't expect the rainbow of colors
you see in some images of Saturn - it's often rendered in false color to emphasize subtle
brightness differences. Saturn will appear as a pale yellow ball, perhaps with some dusky
banding, and the rings will be a brilliant white.
Here is an excellent image taken by SBAU member Bob Richard which will give you a bit of
the flavor, but you really don't get the full effect of Saturn's beauty unless you look
at it live through an eyepiece on a night with steady seeing.
All of our gas giant planets have ring systems, but Saturn's are the most extravagant.
The easily visible portion of the rings spans about 200,000 miles, almost from Santa Barbara
to our Moon, but they are only about 1,000 feet thick. Proportionately, they are thinner
than a razor blade. They are not solid, but are made up almost entirely of water ice, in
chunks ranging in size from smoke particles to mobile homes.
The ball of the planet would hold 750 Earths in volume, and yet because of the preponderance
of hydrogen and helium in its makeup, Saturn is less dense than water. If you had a bathtub
big enough, Saturn would float in it (but it would leave a big ring).
When Galileo looked at Saturn with his little telescope 400 years ago, he couldn't tell that
what he was seeing was a ring, so he said that Saturn seemed to have big ears. It wasn't until
four decades later that Christiaan Huygens, a Dutch astronomer, was able to recognize and
describe it as a ring.
The Cassini spacecraft has been orbiting Saturn and its retinue of 62 moons (at last count) since
2004, and it's still going strong. You can see all kinds of spectacular images at the mission's
website. The spacecraft is about the size of a school bus, and took 7 years to get to Saturn.
And, if you want to be in a picture with Saturn, here's your big chance. On Friday, July 19,
between 2:27 and 2:42 PM PDT, step outside and wave at the sky toward our ocean horizon. Cassini
will be behind Saturn from our point of view, taking an image as Saturn eclipses the Sun. The Earth
will be in the picture, all of about six blue pixels across, and you'll be in there somewhere.
Wear something bright.
If you want to see Saturn for yourself, visit the Santa Barbara Astronomical Unit at one of
our public star parties around the county. We host stargazing (weather permitting) at the Santa
Barbara Museum of Natural History, Westmont College, Camino Real Marketplace, Cachuma Lake,
Refugio State Beach, Carpinteria State Beach, and Bacara Resort and Spa. You can bet that if
Saturn is up, we'll be looking at it. And if you're not in Santa Barbara, you can find astronomy
events and clubs all across the US on NASA's Night Sky Network.
Links for a Cloudy Evening
The Cassini Mission
Wave at Saturn Day
The Santa Barbara Astronomical Unit
The Night Sky Network
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