On Dec. 21, 1968, the Apollo 8 crew leaves the Kennedy Space Center’s then-named Manned Spacecraft Operations Building during the mission’s prelaunch countdown on the way to their history-making lunar orbiting flight. via NASA http://ift.tt/2zbwlJX

Greetings from @Astro_Sabot, otherwise known as Mark Vande Hei, from aboard the International Space Station. via NASA http://ift.tt/2z6xNx8

Acquired on November 29 by Operation IceBridge during a flight to Victoria Land, this image shows an iceberg floating in Antarctica’s McMurdo Sound. via NASA http://ift.tt/2kjgNz4

This schlieren image shows an Air Force Test Pilot School T-38 in a transonic state, meaning the aircraft is transitioning from a subsonic speed to supersonic. via NASA http://ift.tt/2kHqUNB

The two-stage Falcon 9 launch vehicle lifts off from Space Launch Complex 40 at Cape Canaveral Air Force Station carrying the Dragon resupply spacecraft to the International Space Station. Dragon will bring supplies, equipment and new science experiments for technology research to the orbiting laboratory. via NASA http://ift.tt/2BfDjA6

The Soyuz MS-05 spacecraft is seen as it lands with Expedition 53 Commander Randy Bresnik of NASA and Flight Engineers Paolo Nespoli of ESA (European Space Agency) and Sergey Ryazanskiy of the Russian space agency Roscosmos near the town of Zhezkazgan, Kazakhstan on Thursday, Dec. 14, 2017. via NASA http://ift.tt/2ytt3kN

This image from NASA’s Mars Reconnaissance Orbiter (MRO) of northern Meridiani Planum shows faults that have disrupted layered deposits. via NASA http://ift.tt/2iXZy5j

Due to its unique evolutionary status, Cassiopeia A (Cas A) is one of the most intensely studied of these supernova remnants. via NASA http://ift.tt/2C6ofVz

The Aug. 21, 2017, total solar eclipse was rare in its long, uninterrupted path over land, which provided scientists with a rare chance to investigate the Sun and its influence on Earth in ways that aren’t usually possible. On Dec. 11, researchers discussed initial findings based on observations gathered during the eclipse. via NASA http://ift.tt/2AszyKt

This false-color image composed of 15 images taken through three color filters by the Galileo spacecraft as it passed through the Earth-Moon system on Dec. 8, 1992. via NASA http://ift.tt/2A4N6I1