Total Lunar Eclipse

If you have clear skies, be sure to take the opportunity to view the total lunar eclipse of December 20/21, 2010. My forecast isn’t looking good, but I’m holding out hope that I’ll get a clear view and get some photographs of the event. The following image does a great job of detailing when to look, and what you can expect:
Total Lunar Eclipse of December 2010
*Note, the times listed on this image are for Alaskan time, which is 4 hours earlier than Eastern time.
I got the image from Mr. Eclipse who not only explains what you’re seeing, but provides a wealth of other information, including how to photograph it.

A lunar eclipse occurs when the Moon enters the shadow of Earth. This can only happen during a full moon, but not every full moon coincides with an eclipse. Why? Because the Moon’s orbit is inclined about 5.1° to the Earth. So a lunar eclipse will occur when a full moon also happens to be on the same plane, or 0°, as the Earth.

If you’re plagued by cloudy skies, you can still watch it and participate in a live chat, courtesy of NASA/JPL.

So there you have it, no excuses. If you miss this one and reside in the North America, you won’t have another chance until 2014.

Happy observing!

Pac-Man On Mimas

Saturn’s icy moon, Mimas, has long been remarked for its large Herschel Crater giving it the appearance of the Death Star, the fictional space station of Star Wars fame.

Mimas

Death-Star-esque Mimas, imaged by Cassini — Click for high-resolution view

Perhaps Mimas inspired George Lucas when creating the Death Star? Nope; Voyager was the first to give us close-up views of Mimas, a few years after ‘A New Hope’ was in theatres.

But earlier this year, Mimas revealed another uncanny secret resemblance to something out of recent pop-culture history: Pac-Man!

Mimas Temperature Map

Mimas Temperature Map – Click for a Pac-tastic Larger Version

So what we’re seeing here is a map of temperature differences placed over a visual-light image of Mimas. If you think it’s curious that the highest temperatures seem to vary in such a way, you’re not alone:

“Even though we can’t explain the observed pattern of surface temperatures on Mimas, the giant Herschel crater is a leading suspect[.]” “The energy of impact that created it several billion years ago has been estimated to be one-seventh of Mimas’s own gravitational energy. Anything much larger would likely have torn the moon apart. We really would like to see if there is also an anomalous temperature pattern on the other side of Herschel, which has not been observed so closely.” – Dr. Mike Flasar, composite infrared spectrometer principal investigator from NASA Goddard Space Flight Center.

The following image gives an idea of how what’s actually occurring on Mimas compared to what would previously be expected:

Comparison of different images of Mimas.

Comparison between expected temperature-map, actual temperature-map, visual light, and actual temperature-map layered on visual light images. – Click for full version.

A leading theory is that different textures of surface materials (mostly water ice with small amounts of rock) are holding on to heat from the Sun differently, but what is still not understood is why such sharp boundaries exist between these textures — giving the Pac-Man shape. It’s possible that the impact that caused the Herschel Crater distributed the more heat-absorbent materials in that pattern, but Mimas is constantly bombarded by impacts (as can be clearly seen when viewing the high resolution image of Mimas above), which you’d expect to destroy long ago any non-uniform surface make-up.

So for now, no definite answer is available. Luckily, we have the amazing Cassini orbiter up there, collecting more data for the scientists to work with.

The Deathstar…. Err… Mimas

Cassini never ceases to amaze me.

Saturn has moons. Lots of moons (at least 62). And I find each one of those moons to be equally interesting.

Recently, the orbiter, Cassini, snapped the following photo of one of Saturn’s moons, Mimas.

Mimas
(Click image to BIGGIFY)
Mimas is the twentieth largest moon in our solar system, yet is the smallest astronomical body that is believed to be round in shape due to its self-gravitation. Mimas has an interesting feature in a huge crater named Herschel. Compared to Mimas, this crater is huge. It is 80 miles (130km) wide, which is about a third of the total size of the moon itself (wider than Canada). As Phil Plait points out, the impact that created this crater was just about as big as it could have been without obliterating Mimas.

The results are beautiful. Some see the crater resembling a big eye. To many, including myself, it looks like the Deathstar:
Deathstar
(That’s no moon. It’s a space station. – Obi-Wan Kenobi)

For a mission that began in 1997, Cassini (Cassini-Huygens originally, until the Huygens probe was sent to land on the surface of Titan) just keeps on keepin’ on. It has had its missions and extended multiple times, and will most likely keep snapping these shots until it makes a flaming plunge into Saturn’s atmosphere in 2017. NASA, and its counterparts from around the globe, have done a fantastic job of completing their main missions, and then coming up with ways to continue using them for additional missions. We’re learning new and amazing things on a regular basis, and I think that’s just grand.