Dione

Another amazing Cassini photo...

Saturn's moon Dione is placed in a setting here that's straight out of one of those awful pulp science-fiction paperbacks -- the bright grey moon set against the majesty of the giant planet Saturn. From the Cassini web site:

Speeding toward pale, icy Dione, Cassini's view is enriched by the tranquil gold and blue hues of Saturn in the distance. The horizontal stripes near the bottom of the image are Saturn's rings. The spacecraft was nearly in the plane of the rings when the images were taken, thinning them by perspective and masking their awesome scale. The thin, curving shadows of the C ring and part of the B ring adorn the northern latitudes visible here, a reminder of the rings' grandeur.

It is notable that Dione, like most of the other icy Saturnian satellites, looks no different in natural color than in monochrome images.

Images taken on Oct. 11, 2005, with blue, green and infrared (centered at 752 nanometers) spectral filters were used to create this color view, which approximates the scene as it would appear to the human eye. The images were obtained with the Cassini spacecraft wide-angle camera at a distance of approximately 39,000 kilometers (24,200 miles) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 22 degrees. The image scale is about 2 kilometers (1 mile) per pixel.

When I first saw this image, I thought that the edge-on rings were some kind of camera artifact, and I thought that the ring's shadows were the result of either a time exposure or some artist "cleaning up" the photo. The fact that those are real elements in the photo -- we'd see them if we were there -- makes this somehow even more astonishing to me.

Oh, what I would give to be able to take a seat in Cassini, and see with my own eyes what our precocious robot is seeing...

As usual, click on the photo for a larger view...

APOD

AE Aurigae: The Flaming Star

APOD brings us...

Is star AE Aurigae on fire? No. Even though AE Aurigae is named the flaming star, the surrounding nebula IC 405 is named the Flaming Star Nebula, and the region appears to harbor red smoke, there is no fire. Fire, typically defined as the rapid molecular acquisition of oxygen, happens only when sufficient oxygen is present and is not important in such high-energy, low-oxygen environments such as stars. The material that appears as smoke is mostly interstellar hydrogen, but does contain smoke-like dark filaments of carbon-rich dust grains. The bright star AE Aurigae, visible just below the image center, is so hot it is blue, emitting light so energetic it knocks electrons away from surrounding gas. When a proton recaptures an electron, red light is frequently emitted, as seen in the surrounding emission nebula. Pictured above, the Flaming Star nebula lies about 1,500 light years distant, spans about 5 light years, and is visible with a small telescope toward the constellation of the Charioteer (Auriga).

Click on the picture for a larger view.

Clancy

In memoriam...

Randy Cassingham is, amongst other things, the author of the weekly email publication This is True (more on that below). Randy's cat Clancy (pictured at right in a favorite pose) was his longtime friend and companion. Yesterday Clancy died, and Randy (of course!) put up a web page that is a tribute to Clancy. On it, he says:

Clancy was a sweet boy who liked sleeping right next to me -- or, more often in the winter, on me. When I rolled over, he'd "surf the wave" and stay right with me, and when I settled down he would too. But in recent months it was getting clear he was in distress. He has always loved to jump up into my arms (I'm tall, and the floor is a long way away, so I taught him to jump up to me rather than rely on me to bend down to pick him up). But over time, his jumps were less and less powerful -- he wasn't making it all the way to my arms. And in recent weeks, he wouldn't even make the attempt; he was simply tired and, perhaps, hurting.

Any of you who are (like us) kept by your animals will recognize and identify with the sentiment that Randy expresses. Read the whole thing!

On This is True: I first ran into this email publication over seven years ago. I subscribed for years to the free edition, but about three years ago upgraded to his "premium" edition. For that entire period I've looked forward to receiving the latest edition each week. It's very hard for this writer to imagine how Randy manages to keep up the consistent quality of this wonderful little publication, issue after issue after issue, but somehow he does it. He never fails to put a smile on my face and to make me laugh out loud (sometimes in inappropriate work situations <smile>!), and usually has some interesting points to ponder. If you're not already a subscriber to This is True, you really should at least go sign up for the free edition. Try it for a while, and I'll bet you'll want to upgrade to the premium edition!

Rain!

And the fire danger drops to near zero...

When I toddled off to bed last night, we'd had a total of about a third of an inch of rain over the past couple of days, and the radar didn't show any more coming. So it was a very pleasant surprise to wake up this morning and discover that overnight we'd had quite a bit more rain -- almost another half inch -- for a total of 0.75 inches (19 mm) in the past two days. And it is raining nicely as I write this.

Now to you folks who don't live in the desert, that may not seem like a lot of rain. For the high-desert chaparral, though, to have this much rain right as our traditional fire season starts means a significant dimunition in the fire danger, for a least a week or two. All the abundant fuel in the chaparral (the dead twigs, leaf litter, etc.) has now been thoroughly wetted, and will not easily catch fire via wind-blown embers. This is the primary mechanism by which chaparral fires spread, so wet fuel is a big deal. And to dry the fuel out after this much rain will take a prolonged period of dry weather -- hence the several weeks of safety purchased by this rain.

Yahoo for the rain!