Best Of NASA

Around 13 times per century, Mercury passes between Earth and the sun in a rare astronomical event known as a planetary transit. Mercury orbits in a plane that is tilted from Earth's orbit, moving above or below our line of sight to the sun. Here is the latest, captured by the Solar Dynamics Observatory on May 9, 2016.

On June 5 2012, the Solar Dynamics Observatory collected images of the rarest predictable solar event-the transit of Venus across the face of the sun. This event lasted approximately 6 hours and happens in pairs eight years apart, which are separated from each other by 105 or 121 years.

Every two to seven years, an unusually warm pool of water-sometimes two to three degrees Celsius higher than normal-develops across the eastern equatorial Pacific Ocean. This warm condition, known as El Niño, can disrupt marine ecosystems and spur extreme weather patterns around the world. To predict it, NASA scientists use computer models that simulate ocean temperatures in the Pacific.

Experience the thrilling events of the first 50 years of NASA missions to the Red Planet, from Viking, to Pathfinder, and Curiosity.

NASA's Mars Reconnaissance Orbiter has clocked more than a decade of service at the Red Planet and has yielded scientific discoveries and magnificent views of a distant world. These images taken by MRO's HiRISE camera are not in true color because they include infrared information in order to be optimized for geological science.

Data from the Suomi NPP satellite is used by NASA scientists to map the full three-dimensional structure of volcanic clouds, allowing a more accurate forecast of where the volcanic ash is spreading. The information will be used by air traffic management to re-route flights around the hazardous ash clouds, which can damage airplane engines.