Cloudless skies allowed a clear view of dust and hydrogen sulfide plumes along the coast of Namibia in early August 2010. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-color image on Aug. 10. Multiple dust plumes blow off the coast toward the ocean, most or all of them probably arising from streambeds. Unlike the reddish-tan sands comprising the dunes directly south of the Kuiseb River, the stream-channel sediments are lighter in color. NASA
On February 5, 1979, Voyager 1 made its closest approach to Jupiter since early 1974 and 1975 when Pioneers 10 and 11 made their voyages to Jupiter and beyond. Voyager 1 completed its Jupiter encounter in early April, after taking almost 19,000 pictures and recording many other scientific measurements. Although astronomers had studied Jupiter from Earth for several centuries, scientists were surprised by many of Voyager 1 and 2's findings. NASA
Our Earth is covered by volcanoes. Volcanoes are breaks in the Earth's cool surface where hot liquid rock from the interior comes out -- sometimes suddenly. In the above image from the ASTER camera aboard NASA's orbiting Terra satellite, snow-capped volcanoes are seen from overhead that compose the picturesque Islands of the Four Mountains in the Aleutian Islands, Alaska. NASA
STS-28 Columbia, Orbiter Vehicle, crewmembers, wearing launch and entry suits, participate in exercises in the JSC crew compartment trainer in 1989. Four crewmembers are pictured in the stations they will man for the launch and entry phases of the mission. They are joined by the fifth crewmember, "borrowed" for a moment from the middeck. NASA
On their way to perform surface experiments, two residents of the first Martian outpost pause to look at their home in this 1991 artist's concept. Extensive use of natural Martian resources for propulsion would greatly reduce the cost of establishing such a base, and in addition to continued use for propulsion, material processing plants would provide products that would minimize reliance on the Earth-to-Mars supply line. NASA
Viking 1 launched aboard a Tital IIIE rocket August 20, 1975 and arrived at Mars on June 19, 1976. The first month was spent in orbit around the martian planet and on July 20, 1976 Viking Lander 1 separated from the Orbiter and touched down at Chryse Planitia. NASA
Cassini takes in a wide-angle view of majestic, golden-hued Saturn, home to our robotic spacecraft for two years now. The ringplane cuts across the center of Saturn's crescent which wears shadows cast by the icy rings. The planet's now familiar blue and pink hues generally are more subtle in high-phase views from the Cassini wide-angle camera. NASA
What are these strange color bands being seen from the International Space Station? The Sun setting through Earth's atmosphere. Pictured above, a sunset captured last month by the ISS's Expedition 23 crew shows in vivid detail many layers of the Earth's thin atmosphere. Expedition 23 Crew/NASA
The Cassini spacecraft looks across the unlit ringplane as Saturn's moon Mimas glides silently in front of Dione. It is often difficult to tell from two-dimensional views like this where the moons are in relation to each other and Cassini. In this instance, Mimas (247 miles across) is on the side of Saturn closest to Cassini and Dione (700 miles across) is on the far side of the planet. NASA
This artist's conception of newly-discovered object 'Quaoar' - orbiting our Sun far beyond Pluto - shows how the tiny object compares to the size of North America. It is the largest object discovered in our solar system since Pluto was found in 1930. NASA
Obama phoned Russia's Vladimir Putin Thursday to discuss a US proposal for resolving the Ukraine crisis. Earlier, the US moved to begin a regimen of sanctions against Russia. Will those be enough to prevent Russia's annexation of Crimea?
[Updated 9:30 p.m. ET] President Obama appealed to Russian President Vladimir Putin late Thursday, during a personal phone call, to agree to direct talks with Ukraine aimed at resolving, through diplomacy rather than military confrontation, Russia's concerns about the future direction of the Ukrainian government and of the rights of ethnic Russians living in Ukraine.