NASA's Cassini spacecraft peers toward a sliver of Saturn's sunlit atmosphere while the icy rings stretch across the foreground as a dark band. http://www.nasa.gov/sites/default/files/thumbnails/image/pia21334-1041.jpg

Hot summer days in Southern California’s Antelope Valley force many aircraft operations to start early in the morning before the sun rises. On a back ramp at Armstrong Flight Research Center on Edwards Air Force Base, a NASA Global Hawk goes through testing of its communication components and satellite connection links in preparation for flight. http://www.nasa.gov/sites/default/files/thumbnails/image/global_hawk_sunrise_testing.jpg

Various researchers are often pre-occupied with the quest for flowing water on Mars. http://www.nasa.gov/sites/default/files/thumbnails/image/pia21763.jpg

Expedition 52 Flight Engineer Jack Fischer of NASA photographed the glowing nighttime lights of an aurora from his vantage point in the International Space Station's cupola module on June 19, 2017. Part of the station's solar array is also visible. http://www.nasa.gov/sites/default/files/thumbnails/image/iss052e004998.jpg

JunoCam images aren’t just for art and science – sometimes they are processed to bring a chuckle. http://www.nasa.gov/sites/default/files/thumbnails/image/pia21394.jpg

This week in 1966, the AS-203 rocket launched from NASA’s Kennedy Space Center. The Apollo AS-203 mission was an uncrewed test of the vehicle’s second stage, the S-IVB stage, and the instrument unit of the Saturn V to obtain flight information under orbital conditions. http://www.nasa.gov/sites/default/files/thumbnails/image/s66-44314orig.jpg

Vice President Mike Pence addresses NASA employees, Thursday, July 6, 2017, at the Vehicle Assembly Building at NASA’s Kennedy Space Center (KSC) in Cape Canaveral, Florida. http://www.nasa.gov/sites/default/files/thumbnails/image/34954147843_64a8dca7a6_o.jpg

Wind is a force to be reckoned with. It can stir up monsoons, carry dust thousands of miles, and sculpt rock into sinuous arches. But sometimes, the effects of wind go unnoticed for years, like when it carves away slowly at the edges of a pond. http://www.nasa.gov/sites/default/files/thumbnails/image/mississippi_oli_2016336_lrg.jpg

The light of a new day on Saturn illuminates the planet’s wavy cloud patterns and the smooth arcs of the vast rings. http://www.nasa.gov/sites/default/files/thumbnails/image/pia21336_full.jpg

On May 29, 2017, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this image of ice covering the Amundsen Gulf, Great Bear Lake, and numerous small lakes in the northern reaches of Canada’s Northwest Territories and Nunavut. Icy lakes and rivers make a significant footprint on the Arctic landscape. http://www.nasa.gov/sites/default/files/thumbnails/image/amundsengulf_tmo_2017149_lrg.jpg

This year, NASA is celebrating the 100th anniversary of the agency’s Langley Research Center in Hampton, Virginia. In Langley's early years of crafting flight, aviation pioneers flocked to the center for engineering conferences. This photo was taken in Langley's Full Scale Tunnel during the 1934 Aircraft Engineering Research Conference. http://www.nasa.gov/sites/default/files/thumbnails/image/1934conference.jpg

This enhanced-color image of Jupiter’s Great Red Spot was created by citizen scientist Gerald Eichstädt using data from the JunoCam imager on NASA’s Juno spacecraft. http://www.nasa.gov/sites/default/files/thumbnails/image/pia21773.jpg

NGC 2500 is a particular kind of spiral galaxy known as a barred spiral, its wispy arms swirling out from a bright, elongated core. http://www.nasa.gov/sites/default/files/thumbnails/image/potw1728a_0.jpg

When astronauts return to Earth from destinations beyond the moon in NASA’s Orion spacecraft and splashdown in the Pacific Ocean, they’ll still need to safely get out of the spacecraft and back on dry land. Using the waters off the coast of Galveston, a NASA and Department of Defense team tested Orion exit procedures on July 10-14, 2017. http://www.nasa.gov/sites/default/files/thumbnails/image/35084833674_e2e44cc938_o.jpg

A medium-sized (M2) solar flare and a coronal mass ejection erupted from the same, large active region of the sun on July 14, 2017. The flare lasted almost two hours, quite a long duration. The coils arcing over this active region are particles spiraling along magnetic field lines. http://www.nasa.gov/sites/default/files/thumbnails/image/pia21836.jpg

This photograph of the Lunar Module at Tranquility Base was taken by Neil Armstrong during the Apollo 11 mission, from the rim of Little West Crater on the lunar surface. Armstrong's shadow and the shadow of the camera are visible in the foreground. This is the furthest distance from the lunar module traveled by either astronaut while on the moon. http://www.nasa.gov/sites/default/files/thumbnails/image/as11-40-5961hr.jpg

Tucked away in the small northern constellation of Canes Venatici (The Hunting Dogs) is the galaxy NGC 4242. http://www.nasa.gov/sites/default/files/thumbnails/image/potw1729a.jpg

Expedition 52 Flight Engineer Jack Fischer of NASA shared photos and time-lapse video of a glowing green aurora seen from his vantage point 250 miles up, aboard the International Space Station. This aurora photo was taken on June 26, 2017. http://www.nasa.gov/sites/default/files/thumbnails/image/iss052e007857.jpg

The Soyuz MS-05 spacecraft is seen as it is raised into a vertical position on the launch pad at the Baikonur Cosmodrome, Kazakhstan, Wednesday, July 26, 2017. The Expedition 52 crew is scheduled to launch to the International Space Station aboard the Soyuz on Friday, July 28, at 11:41 a.m. EDT (9:41 p.m. Baikonur time). http://www.nasa.gov/sites/default/files/thumbnails/image/36132963076_4dd2651525_o.jpg

This false-color view from NASA's Cassini spacecraft gazes toward the rings beyond Saturn's sunlit horizon. http://www.nasa.gov/sites/default/files/thumbnails/image/pia21621-1041.jpg