Every time I think Cassini can’t possibly send back a more dramatic image from Saturn, it takes my preconceived notions and crushes them to dust.

Oh. My.

That shows the moons Titan (in the background) and Rhea, the two largest of the gazillions of moons circling the ringed planet. Titan has an atmosphere, which is why it looks fuzzy.

This picture is crazy amazing! Rhea looks like it’s about to smash into Titan — if you’re curious, this is what my nightmares look like — but in fact they’re very far apart. Rhea was about 1.1 million kilometers (680,000 miles) away from Cassini when this was taken, and Titan was more than twice that. So they were actually separated by over a million kilometers, about three times the distance of the Moon from the Earth! Cassini used the narrow-angle camera (essentially a big telescope) to get this shot, so it looks foreshortened — Titan is actually more than three times wider than Rhea, but it looks smaller than that here because it’s twice as far away. The two moons are in no danger of collision.

What a stunning shot! And I love how these two worlds are so different. Icy Rhea is pitted and cratered, but Titan’s thick atmosphere smudges out all details in visible light. Together, they’re an excellent example of diversity in the Saturn system, and a reminder of just why we sent Cassini there in the first place.

Tip o’ the spacesuit visor to Carolyn Porco. Image credit: NASA/JPL/Space Science Institute

After yesterday’s depressing picture, how about one that will make you smile?

The ever-amazing Cassini spacecraft sent back this pretty nifty shot of Saturn’s icy moon Rhea playing peekaboo in the rings:

Beautiful, isn’t it? You can see that Rhea was on the other side of the rings from Cassini when this image was taken, and that the spacecraft was almost, but not quite, in the plane of the rings, too.

But there’s more to this shot… (more…)

If you need a little more awesome in your weekend, then try this:

I know I’ve been posting quite a few Saturn images from Cassini, but I really like this one. It shows the big round moon Rhea, the lumpy small moon Janus, and a lovely view of the foreshortened rings. Both moons were on the far side of the rings, well over 1 million kilometers away, when Cassini took this shot. Rhea is over 1500 km (900 miles) in diameter, while Janus is only about 180 km (110 miles) across. For comparison, our own Moon’s diameter is almost 3500 km (2100 miles).
(more…)

It might seem like a tautology — and that’s because it is — but sometimes the only word you can use to describe an image from the Cassini Saturn probe is otherwordly:

[Click to engasgiantize.]

This otherworldy picture was taken on March 24, 2010. The big moon is Rhea, seen from 1.2 million kilometers (750,000 miles) away, and the little one below it is Epimetheus, from 1.6 million km (990,000 miles) away. Perspective makes them look right next to each other, but in reality the distance between them is the same as the Moon from the Earth! Saturn and its rings provide the backdrop for this stunning alien portrait.
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Same shape, different moon…

An interplanetary dedication of love for all you starry-eyed geeks:

This is an image from Cassini. It’s a closeup of a crater on Rhea, a moon of Saturn about half the size of our own natural satellite. I love how the small crater and ridge inside the bigger crater make it look like the heart is winking!

In the full size image you can see what looks like a ridge to the left of the heart, but in fact that’s the edge of a vast crater on the surface of Rhea. You can see it better in this image of the whole moon, where I’ve marked the location of the heart:

I don’t know exactly what’s going on with this heart; is it a crater that expanded when the walls collapsed around it, so it’s no longer round? Or is it a sink hole, where the whole thing is a collapse feature? I love pictures like this, showing us the diversity and cool-factor of other worlds in our solar system.

And, of course: Happy Valentine’s Day.

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Scientific Valentines
The beating heart of W5
Have an astronomical Valentine’s Day

We live on a wonderful planet with a beautiful Moon. But I sometimes think we got gypped.

The view from Saturn can be sooooo much cooler:

That’s the moon Enceladus passing in front of (what we science-types call "transiting") Rhea. Enceladus is about 500 km (300 miles) across and Rhea is 3 times bigger. Rhea was about 2.7 million km (1.7 million miles) from Cassini when these shots were taken, and Enceladus a bit closer at 2.3 million km (1.4 million miles). Of course, by a bit closer I mean the same distance our Moon is from the Earth, so there was plenty of room for this mutual event.

Here’s a zoom of the middle frame:

Awesome. Note that these images were taken about one minute apart, so things were hopping. It’s amazing to me that not only can we put a probe around Saturn and get images of its moons, but our math and physics are so freaking accurate we can say, "Hey, you know what? On this date at this time if we turn Cassini that way we’ll see a moon over 2 million kilometers away pass in front of another one nearly 3 million kilometers away."

Every morning, I have a 50/50 chance of finding my keys. That kinda puts things in perspective.

I don’t have a whole lot to add to this amazing shot from Cassini of Saturn’s moon Rhea reappearing from behind the giant moon Titan:

[Click to entitanate.]

Except: coooool. Titan is over three times the size of Rhea, and Rhea was more than twice as far from Cassini when this was taken, making Rhea look even smaller in comparison. Also, check out how the high-altitude haze in Titan’s atmosphere isn’t the same height all the way around the moon. Near the top you can see they poof up higher. If you look closely, can you see the Enterprise?