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.

(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:
(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.

Ursa Major

The following video is my first real attempt at time-lapse astrophotography. I chose one of my favorite constellations, Ursa Major (best known for containing The Big Dipper). The video shows the motion of the constellation over a 45-minute period.

I live in a small city, so some light pollution factored into the result but overall the night was quite clear. You can clearly make out “The Horse and Rider”, two stars that make up what is typically seen as the second star in The Big Dipper’s handle. The ability to see these two stars, Mizar and Alcor, was used by the Arabs, Romans, and English to test the eye-sight of their warriors.

But there’s even more to Mizar and Alcor than meets the (unaided) eye. Mizar is actually a quadruple system of two binary stars and Alcor is a binary system. Together, they make up sextuple system, as they are all apparently gravitationally bound.

To put it simply, Mizar — which we see as the brighter star, the horse, making up the Horse and Rider — is two sets of two stars orbiting each other. Alcor, is a single set of two stars orbiting each other, and is in turn interacting with the Mizar system. Six stars, dancing together in a cosmic folk dance, appearing to us on Earth as one or two stars (depending on your eyesight).

Additionally, this all goes to show that as much as we think we know about the cosmos, there is so much more out there to discover. Mizar and Alcor have been two of the most observed objects in the night sky for millennia, yet we still continue to unravel more of their magic.

Ursa Major

Ursa Major

Black Eye Galaxy

Black Eye Galaxy
(click image to largeify)

The Black Eye Galaxy (Messier 64), in the constellation Coma Berenices, is a spiral galaxy, visible with even a small telescope. It was discovered in 1779, by Edward Pigott (and independently a month later by Johann Elert Bode and in 1880 by Charles Messier). In a majority of galaxies, the stars all orbit in the same direction. Interestingly though, the gases in the outer region of M64 rotate in the opposite direction of the gases and stars within the inner region. To clarify the scale, the inner region has a radius of 3,000 light years, while the outer region extends an additional 40,000 light years. (That’s big, but take note that M64 is 19,000,000 light years from Earth.) The boundary between the two regions is believed to trigger a very productive birthing ground for many new stars. Astronomers believe that this pattern was caused when M64 absorbed a satellite galaxy brought in on a collision course, approximately 1 billion years, or more, ago.

The darkened band that gives the galaxy it’s nickname is a dust feature that’s obscuring the light from the nucleus of the galaxy.

Dying A Beautiful Death

The red giant AFGL 3068 is dying a beautiful death. Like all red giants, as they expand they spew their outer layers into space in a spherical shape. What’s unique about AFGL3068 however, is that it’s actually a binary star — two stars orbiting each other. Due to the orbits of the two stars, the material that’s ejected isn’t able to expand into a sphere, but in this amazingly perfect (and awesomely huge at 3 trillion kilometers!) spiral.

Look for yourself:

AFGL 3068

AFGL 3068

(Click image to embiggerify)

Thanks Hubble!