It’s gorgeous. There’s so much to see! North is to the upper left (roughly the 11:00 position), and the pole looks like it’s covered in a cloudy haze [Update (Sep. 29, 2014 at 17:40 UTC): Ah, according to my friend and fellow science writer Carolyn Collins Petersen, that's a dust storm brewing there.]. The huge, lighter-colored region just to the right and above center is called Arabia Terra, a 4,500-kilometer stretch of uplands that is one of the oldest terrains on Mars. It’s hard to tell from this wide-angle shot, but it’s heavily eroded and covered with craters.
Just below it is a long dark feature called Terra Meridiani (“Meridian Land”; though you could fancifully call it “Middle Earth”). The rover Opportunity is there, still roaming around and poking at the rocks there. This whole area shows evidence that is was once under water.
Nestled in the northern part of Terra Meridiani is the crater Schiaparelli, which is more than 460 km across! That’s huge, far larger than the crater left by the dinosaur-killer impact here on Earth. Straight up from it in Arabia Terra you can also see the crater Cassini (also more than 400 km wide), and to the right, just inside the dark region called Syrtis Major, is the crater Huygens, which is about the same size as Schiaparelli. The astronomers Cassini and Huygens studied Saturn, which is why the Cassini probe is named what it is, and the lander probe it sent to the moon Titan is named Huygens. Those astronomers really get around.
I could go on and on; you can see Hellas Basin as a smooth, butterscotch-colored area to the lower right just on the edge, and the ices of the south pole at the bottom. There are craters galore, and all sorts of wind-eroded areas that so many scientists will happily spend the rest of their lives studying.
But for me, right now, what makes me sigh in awe is the overall perspective of this picture. We’re seeing the entire face of the planet here, a perspective we don’t always get from our probes, sent to study Mars in detail. And the added touch of it not being fully lit—you can see the day-night line, called the terminator, cutting across the planet to the upper left—really drives home that what we’re seeing here really is an entire world, a huge expanse of territory just calling out for us to explore and understand.
There’s a lot of solar system out there to look at, and it fills me with joy to know we’re doing just that.