23.9.06

Three Occultations

And instead of saying all of your goodbyes - let them know
You realize that life goes fast
It's hard to make the good things last
You realize the sun don'-go down
It's just an illusion caused by the world spinning round


I'm surprised they allowed me to have a blog for this long without quoting some song lyrics on it. From Do You Realise? by the Flaming Lips. It must be a mark of true musical ability to actually sing these lines, because as much as I love them, I certainly can't do it.

I've been catching up with our old robot buddy Cassini today. Here are three sets of images with a common theme...



In this image from June, icy Rhea is just nudging in front of Titan. Although Rhea is Saturn's second largest moon (after Titan) it lacks the dense atmosphere and liquid lakes of its bigger sibling, and plays second fiddle to third largest Iapetus with its eerie dark patch. Even tiny Enceladus with its water geysers gets more attention. So I think we can forgive it for pushing into the limelight just this once.





In the image below, taken a month later, Rhea is centre stage, with little Enceladus peeping over its shoulder.





As noted by the Planetary Society, Cassini recently had a great opportunity to make some intriguing observations. Carolyn Porco eloquently explains the event in her "captain's log" at the Cassini imaging team (aka. CICLOPS) homepage:

A few days ago, the spacecraft carried us far from the planet and deep within its shadow, completely blocking out the direct rays of the sun. Shaded by the planet, we can peer closer to the sun -- a geometry known as `high phase' -- than our instruments can usually tolerate. From this viewpoint, the tiny particles of water ice that populate certain regions around Saturn brighten substantially, just like the dust on your car's windshield becomes very obvious as you drive into the sun. This is the process of diffraction, and scientists utilize this consequence of the interaction of electromagnetic radiation with small particles to locate and map those locales in circum-Saturnian space where small particles are being created by a variety of processes.


Here, for example, we see Enceladus wandering happily along the ring that it itself generates with its jets of water vapour. As it moves through the ring (anti-clockwise in this image), it both disrupts it and contributes to it further. The bright speck above and to the left of Enceladus is Tethys, another moon.


The image that is garnering the most attention though, is a distant view of a strange and wondrous world, for which I will again borrow Porco's finely crafted words:

[A]s we looked back in the direction of the sun, we captured from across the depths of space our own planet, a pale blue orb, seen amidst the pageantry and colorful splendor of Saturn's rings. Nothing has greater power to alter our perception of ourselves and our place in the cosmos than the sight of Earth from faraway places. In the end, this ever-widening view of our own little planet against the immensity of space is perhaps the greatest legacy of all our interplanetary travels.


Earth is the speck in the top-right quadrant. Enceladus is also visible in the left of the image. Dr Porco was part of the imaging team that processed a similar image from Voyager 1 while beyond Neptune, an image that led to these famous musings.

4 comments:

zhoen said...

Actually, since I was never very good at spotting planets in our own sky, I'd assumed Earth would be hard to see from other planets.

tinker said...

Wow! I had to clean off my computer screen to make sure which tiny speck we were; makes me feel rather amoebic or atomic, I'm not sure which...very, very tiny - microscopic in the scheme of things. I'd like a cup of tea now, please ;)

susanna said...

I have to admit, I'm terribly ignorant when it comes to planets and space and anything "out there". Carl Sagan's piece was really moving, though. Now why couldn't that article be published on the front page of the Washington Post or read out loud on al jazeera?

Crafty Green Poet said...

Amazing images, yes it is indeed sobering to see our planet from such a distance.