Category Archives: astronomy

astronomy, cassini mission

Messing With the F Ring

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What Two Moons Can Do

The shredded F ring of Saturn, as seen by the Cassini-Huygens mission narrow-angle camera on January 11, 2009. (Click to embiggen.)
The shredded F ring of Saturn, as seen by the Cassini-Huygens mission narrow-angle camera on January 11, 2009. (Click to embiggen.)

Earlier this year the Cassini-Huygens mission studied the delicate F ring that winds a delicate strand of debris around Saturn. The F ring is the outermost of the rings and is only a few hundred kilometers wide.

It turns out that the F-ring is disrupted by the action of the two moons that also work to keep it on the clumpy and narrow. Prometheus and Pandora both interact with the ring, and occasionally they work to disrupt the material in the ring — giving it a somewhat jagged, clumpy, and very ethereal appearance. Prometheus’s orbit encounters the ring and when it does, this tiny moon’s gravitational pull tugs at the ring material, causing the disrupted appearance. It’s almost as if the moonlet is slicing material out of the ring as they move along together around Saturn.

Animation showing how two moons sculpt and disrupt the F ring at Saturn. (Click to embiggen.)
Animation showing how two moons sculpt and disrupt the F ring at Saturn. (Click to embiggen.)

The F ring is made of particles of ice and dust that swarm in orbit around the planet, and was first seen in images from the Pioneer spacecraft. Subsequent Voyager images showed more detail in the ring — and at that time, I remember scientists referring to the “kinky” F ring because of the mysterious knotted structure they were seeing in the Voyager images.

If you could be in a spacecraft hovering above the F ring and watch it for a few hours, you’d see the view changing continually, as it appears to do in this animation (below).  Amazing what we can learn by watching for just a few hours, eh?

astronomy, evolution of galaxies, galaxies, galaxy interactions, galaxy shapes

View from a Distance

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Galaxy Beauty

What if you could move anywhere in the cosmos just to get a good view? Where would you go? The view from our own planet takes in the interior of our own galaxy, plus a healthy look out to intergalactic space. We can see, literally, for billions of  light-years, provided we use the right instruments.  But, what if you could live on a world at the rim of a distant galaxy that was overlooking a pair of interacting galaxies?  What you like this to be your view?

NGC 1532/1 as seen by ESOs 1.5-meter Danish Telescope. (Click to embiggen.)
NGC 1532/1 as seen by ESO's 1.5-meter Danish Telescope. (Click to embiggen.)

This is a pair of galaxies called NGC 1531/2 and they lie about 70 million light-years away from Earth. From this point of view, we can tell they are interacting in a sort of spirited galactic waltz. The spiral galaxy in the foreground is being warped by its dance with the smaller galaxy just above it. The cosmic dance leads to another dramatic effect: a whole new generation of massive stars that were created in the chaos of collision during the dance.  They are visible as the purple objects in the spiral arms.

This view from your living room window on that distant planet I mentioned above is really an exquisite image from the European Southern Observatory. It was made by R. Gendler and J.-E. Ovaldsen who used the 1.5-meter Danish telescope to capture the image.

I often wish we had dramatic views like this from our own back yards here on Earth rather than the skies we do have. On the other hand, using telescopes like the ones at ESO, we really kinda do.  So, enjoy!!