Tuesday, September 27, 2005

Cassini spots huge "spear" on Saturn moon

The first close-up images of Saturn's moon Tethys have been sent to Earth from the Cassini spacecraft, which flew past the moon on Saturday. As well as the expected craters and chasms, one image reveals a peculiar, spear-shaped feature.


If you enlarge the image and look closely, you can make out several narrow linear features like the hilt of the so-called "spear."

8 comments:

infotheorem said...

the saturnian system is a weird place

W.M. Bear said...

That's an awfully straight "shaft" on the "spear." Honestly, my first impulse really is to come up with a convincing natural explanation for features like this. I'm no geologist, so maybe that explains most of my failure. Except that I don't see professional planetary geologists coming up with any "good" explanations either. Mostly, they seem just to steer clear of the subject, which is probably the smartest approach from their perspective.

W.M. Bear said...

The "spear" also seems to be pointing right at a kind of conical hill or mound. Like it's saying, "Hint, hint. Dig here."

W.M. Bear said...

There's also what looks to be a very narrow shadow (like, yes, the shadow of a tower) on the upper side of the "spearhead." (This feature is clearly visible when you enlarge.) And the sun angle seems right for it to be a real shadow and not just dark surface discoloration.

Carol said...

That's Mr. Crocodile's head, with his little hat. His spine is very straight because his governess always insisted that her charges have impeccable posture.

Fault line that filled in with a harder rock, then the softer rock around it eroded away leaving it in relief?

Mac said...

Carol--

They're *obviously* hyperdimensional vacuum trains.

W.M. Bear said...

Spaceflightnow gives the following information on this picture (actually on a color filter version of the SAME picture).

The clear filter images in this mosaic were taken with the Cassini spacecraft narrow-angle camera at distances ranging from 71,600 kilometers (44,500 miles) to 62,400 kilometers (38,800 miles) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 21 degrees. The image scale is 370 meters (1,200 feet) per pixel.

Counting the pixels in the shadow, I used this information to make a (very) rough calculation of the width and height of whatever is casting that rectangular shadow. I got a height of roughly 33,500 feet for the object and a width of about 3,600 feet. That's a height-to-width ratio of 9.3 to 1. If you draw a rectangle (and the shadow does look more or less rectangular) with these proportions, it becomes increasing difficult to think of this object as somehow "natural."

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