This image is a rendering of a 3D model of the Mojave Crater on Mars. The image was crafted from stereo images acquired by the Mars Reconnaissance Orbiter, and spans about 4km. This is just a small portion of the crater's edge, since the crater itself is 60km across. This image also has its vertial relief enhanced 3x over that in the horizontal direction. Note that this part of the crater appears filled in, like a pond. This ponding is thought to occur when melt generated by an impact is captured behind mountainous walls. The dearth of additional smaller craters tells us this feature is relatively young for Mars, only 10 million years old. Note also the flows into and out of this region. They suggest that the impact event might have melted underground ice that also flooded this region.
NASA's WISE mission (Wide-Field Survey Explorer) is a new spacescraft that is designed to map the sky at infrared wavelengths. The above shows a color image comet Siding Spring seen at 3-22 microns, which is rather redwards of visible light having wavelengths of ~0.6 microns. This image is colored so that the hotter stars appear blue while the much cooler cometary dust tail is red. A tail forms when the comet passes near the Sun, which warms the comet's icy surface. As the comet's icy surface sublimates (boils off), the water vapor also liberates tiny dust grains. Radiation pressure, which is the weak force that sunlight exerts on these tiny dust grains, then sweeps these particles away into a tail that can span millions of miles. See the WISE website for more details.
David Jewitt (UCLA) acquired this new Hubble image of the mysterious dust trail that appeared recently in the asteroid belt. This trail is also discussed in this January 20 post. Current thinking says that this debris from a recent collision among two asteroids. Check the Hubble page for more details.