Enjoy this remarkable video of potato-shaped Phobos, the 11.2-km-in-diameter moon of Mars passing in front of the sun taken by the robot Curiosity from the surface of Mars:
And the image above makes a wonderful Partial Ellipsis/Eclipse of the Sun logo, methinks.
Phobos is only 6000 km from the surface of Mars so even though it is much smaller than the Earth's moon it appears to eclipse less of the sun and does so in splendid, craggy, Mr. Potato Head detail.
Keep your eyes on Phobos, though, because it is moving a meter or more closer to Mars every century. In 10-15 million years (though some researchers think it will be longer, up to 50 million years) it will likely be pulled into Mars by its tidal forces and break up to become just another planetary ring. Phobos orbits Mars once every 8 hours.
This phenomenal, enhanced photo shows clearly the Stickney crater on Phobos:
This main crater on Phobos was named by Asaph Hall in 1877 for his wife, Chloe Angeline Stickney Hall, a mathematician, abolitionist and suffragist. Note the smaller crater within the larger crater.
The striations (see below) on Phobos were originally thought to be related to the crashing of the object which created the large Stickney crater. However, these striations are centered on the leading apex of Phobos in its orbit (which is not far from Stickney). Researchers believe that the striations have been excavated by material ejected into space by impacts on the surface of Mars. The striations thus formed as crater chains, and all of them fade away as one moves toward the trailing apex of Phobos.
(There is also some pretty wild stuff out on the interwebs about Phobos being a space station, being formed of sedimentary rock, etc.)
Phobos, from the Greek word for fear, is likely composed mostly of carbonaceous chondrite (or C chondrite). The carbon content is likely to be quite low, however, perhaps less than 2 percent:
Robert Krulwich describes the Phobos partial eclipse well in today's NPR blog (and is credited for today's blog title--it was too perfect for Partial Ellipsis of the Sun to pass up). His description is spot on:
When it Comes to Eclipses, Partial is the new Total
This display at the Denver Public Library titled "I don't remember the title but the cover was green" made me smile.