Astronomy Picture of the Day Index - Solar System: Mars

APOD: 2006 May 15 - Volcanic Bumpy Boulder on Mars
Explanation: What created this unusually textured rock on Mars? Most probably: a volcano. Dubbed Bumpy Boulder, the strange stone measuring just under a half-metre high was found by the robotic Spirit rover currently rolling across Mars. Pits on the ragged rock are likely vesicles and arise from hot gas bubbling out of hot rock ejected by an active Martian volcano. Several similar rocks are visible near Bumpy Boulder that likely have a similar past. The above true-colour image was taken about one month ago. The Spirit rover, now in its third year of operation on Mars, is weathering the low sunlight winter of Mar's northern hemisphere on a hillside slope in order to maximize the amount of absorbable battery-refreshing sunlight.

APOD: 1999 July 5 - Four Faces of Mars
Explanation: As Mars rotates, most of its surface becomes visible. During Earth's recent pass between Mars and the Sun, the Hubble Space Telescope was able to capture the most detailed time-lapse pictures ever from the Earth. Dark and light sand and gravel create an unusual blotted appearance for the red planet. Winds cause sand-tinted features on the Martian surface to shift over time. Visible in the above pictures are the north polar cap, made of water ice and dry ice, clouds including an unusual cyclone, and huge volcanoes leftover from ancient times. The Mars Global Surveyor satellite orbiting Mars continues to scan the surface for good places to land future robot explorers.

APOD: 2001 July 18 - Mars from Earth
Explanation: Last month, Mars and Earth were right next to each other in their orbits. Formally called opposition, the event was highlighted by a very bright Mars for skywatchers and a good photo opportunity for the Hubble Space Telescope. Above, Hubble snapped the highest resolution picture of Mars ever obtained from the Earth. Visible on Mars are ice caps over the poles in white, regions covered with sand and gravel in dark brown and orange, and large dust storms in light orange. A particularly large dust storm can be seen on the lower right pouring out of Hellas Basin. This storm has since erupted into a huge planet wide storm that continues even today. Pictures like these allow planetary astronomers to continue to compare the weather patterns of Mars and Earth. When Mars next reaches opposition in 2003, its elliptical orbit will cause it to be even 20 percent closer.