Mercury's horizon cuts a striking edge against the stark blackness of space, on January 20, 2015. On the right, sunlight harshly brings the landscape into relief while on the left, the surface is shrouded in the darkness of night. #

Mercury, June 21, 2013, the low Sun elevation in this scene emphasizes the topography of Van Eyck crater. The rim of Van Eyck has been profoundly cratered by material ejected from the Caloris basin. Smooth plains fill the floor of Van Eyck, but they too have been affected by cratering, from large primary impacts to deep, linear incisions by secondary crater chains. #

Seen from the ISS on June 4, 2014, the largest salar (salt flat or playa) in the world, Salar de Uyuni, is located within the Altiplano of Bolivia. Covering 10,582 square kilometers (4,086 square miles), the mineral-crusted salar is about the same size as the Big Island of Hawaii. Several mountains, including the dormant volcano Mount Tunupa, cast long shadows across the salars. #

Tropical cyclone Bansi as seen at night by astronauts on the ISS. The images were taken when the ISS was east of Madagascar. Bansi formed in the southwestern Indian Ocean on January 11, 2015. By the time this photo was taken on the following day, Bansi had achieved tropical cyclone strength. The eye of the cyclone is brilliantly lit by lightning in or near the eye wall. The low-light settings of the camera used to take the image accentuate the contrast. #

The United Launch Alliance Delta IV Heavy Rocket with NASA’s Orion spacecraft mounted atop, lifts off from Cape Canaveral Air Force Station's Space Launch Complex 37 on December 5, 2014, in Florida. #

The unmanned Falcon 9 rocket, launched by SpaceX and carrying NOAA's Deep Space Climate Observatory Satellite, lifts off from launch pad 40 at the Cape Canaveral Air Force Station in Cape Canaveral, Florida, on February 11, 2015. The rocket blasted off on Wednesday to put the U.S. satellite into deep space, where it will keep tabs on solar storms and image Earth from nearly 1 million miles (1.6 million km) away. #

This composite Hubble Space Telescope image captures the positions of Comet Siding Spring and Mars in a close passage of a comet by the Red Planet, which happened on October 19, 2014. On that date the comet passed by Mars at approximately 87,000 miles (about one-third the distance between Earth and the Moon). At that time, the comet and Mars were approximately 149 million miles from Earth. #

This view from the Mast Camera (Mastcam) on NASA's Curiosity Mars rover shows a swath of bedrock called "Alexander Hills," which the rover approached for close-up inspection of selected targets. The mosaic of six Mastcam frames covers an area about 6 feet (2 meters) across. It shows details within the workspace accessible using the rover's robotic arm from the rover's location when the view was acquired. The component exposures were taken on November 23, 2014, during the 817th Martian day, or sol, of Curiosity's work on Mars. #

NASA's Curiosity Mars rover (dot at center) can be seen at the "Pahrump Hills" area of Gale Crater in this view from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. The region contains sedimentary rocks that scientists believe formed in the presence of water. The rover, with its shadow extending toward the upper right, is at center. HiRISE made the observation on December 13, 2014. #

This view from the Mast Camera (Mastcam) on NASA's Curiosity Mars rover shows dramatic buttes and layers on the lower flank of Mount Sharp. It is a mosaic of images taken on the 387th Martian day, or sol, of Curiosity's work on Mars (Sept. 7, 2013). The rover's location was near a waypoint stop called "Darwin" on the drive from Yellowknife Bay toward an entry point to reach the mountain. #

A wide-angle camera image acquired by the European Space Agency's Rosetta spacecraft on November 22, 2014 from a distance of 30 km from Comet 67P/Churyumov-Gerasimenko. The image resolution is 2.8 m/pixel. The nucleus is deliberately overexposed in order to reveal the faint jets of activity. #

Two views of the swarf planet Ceres are seen in images acquired by NASA's Dawn spacecraft from a distance of about 52,000 miles (83,000 kilometers) on February 12, 2015. The Dawn spacecraft is due to arrive at Ceres on March 6, 2015. #

Three of Jupiter's largest moons are seen moving across the banded face of Jupiter in these images from NASA's Hubble Space Telescope taken January 24, 2015 and released February 5, 2015. Jupiter's four largest moons can commonly be seen transiting the face of the giant planet and casting shadows onto its cloud tops. However, seeing three moons transiting the face of Jupiter at the same time is rare, occurring only once or twice a decade. #

A color view of Europa from Galileo that shows the largest portion of the moon's surface at the highest resolution. This view was previously released as a mosaic with lower resolution and strongly enhanced color. To create this new version, the images were assembled into a realistic color view of the surface that approximates how Europa would appear to the human eye. The scene shows the stunning diversity of Europa's surface geology. Long, linear cracks and ridges crisscross the surface, interrupted by regions of disrupted terrain where the surface ice crust has been broken up and re-frozen into new patterns. #

This view of Saturn looks toward the sunlit side of the rings from about 25 degrees above the ringplane. The image was taken in red light with the Cassini spacecraft narrow-angle camera on August 23, 2014. #

A view toward the trailing hemisphere of Saturn's moon Mimas. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on June 5, 2012. #

Saturn's great vortex at its north pole, 1,240 miles (2,000 kilometers) across, with cloud speeds as fast as 330 miles per hour (150 meters per second), seen by NASA's Cassini spacecraft on on April 2, 2014. #

Slipping into shadow, the south polar vortex at Saturn's moon Titan still stands out against the orange and blue haze layers that are characteristic of Titan's atmosphere. Images like this, from NASA's Cassini spacecraft, lead scientists to conclude that the polar vortex clouds form at a much higher altitude, where sunlight can still reach, than the lower-altitude surrounding haze. #

Seen from orbit around Saturn, this small blue orb is Uranus, imaged by Cassini for the first time. Uranus has been brightened by a factor of 4.5 to make it more easily visible. The bright ring cutting across the image center is Saturn's narrow F ring. Uranus was approximately 4.3 billion kilometers from Cassini and Saturn when this view was obtained. #

Pluto and Charon, the largest of Pluto's five known moons, seen January 27, 2015, through the telescopic Long-Range Reconnaissance Imager (LORRI) on NASA's New Horizons spacecraft. New Horizons was about 126 million miles (203 million kilometers) from Pluto when the phot was taken. These images are the first acquired during the spacecraft's 2015 approach to the Pluto system, which culminates with a close flyby of Pluto and its moons on July 14. The image was magnified four times to make Pluto and Charon more visible. The image exposure time was only a tenth of a second, which was too short to detect Pluto’s smaller moons. #