Great Barrier Reef Near Whitsunday Islands

An astronaut aboard the International Space Station used a powerful lens to photograph these three reefs in Australia’s Great Barrier Reef on Oct. 12, 2015. Reefs are easy to spot from space because the iridescent blues of shallow lagoons contrast sharply with the dark blues of deep water.

Portland Sunrise

Scott Kelly's Post-Flight Visit to Washington

Former NASA astronaut Scott Kelly speaks about his historic mission aboard the International Space Station during an event at the United States Capitol Visitor Center, Wednesday, May 25, 2016, in Washington.

Hubble's Sharpest View of the Orion Nebula

Chasma Boreale and North Polar Ice Cap of Mars

Mars has bright polar caps of ice that are easily visible from telescopes on Earth. A seasonal cover of carbon-dioxide ice and snow is observed to advance and retreat over the poles during the Martian year. Scientists using radar data have found a record of the most recent Martian ice age recorded in the north polar ice cap.

NASA's OSIRIS-REx Spacecraft Prepared for Mission to an Asteroid

NASA's OSIRIS-REx spacecraft is revealed after its protective cover is removed inside the Payload Hazardous Servicing Facility at Kennedy Space Center, on May 21, 2016. OSIRIS-REx, targeted for a Sept. 8 launch, will be the first U.S. mission to sample an asteroid, retrieve at least two ounces of surface material and return it to Earth for study.

Ben Bullen

Fjord and Glacier in East-Central Greenland

On May 19, 2016, NASA's IceBridge, an airborne survey of polar ice, crossed Greenland to fly central glacier flowlines in the east-central region of the country. This photo captures the fjord of Violin Glacier, with Nord Glacier at the upper left corner. This is IceBridge's eighth spring campaign of science flights over Arctic sea and land.

Manhattan View

Up and Over

Cassini orbited in Saturn's ring plane -- around the planet's equator -- for most of 2015.

CubeSats Deployed From the International Space Station

CubeSats fly free after leaving the NanoRacks CubeSat Deployer on the International Space Station on May 17, 2016. Seen here are two Dove satellites. The satellites are part of a constellation designed, built and operated by Planet Labs Inc. to take images of Earth from space.

May 19, 2000, Early Morning Liftoff of Atlantis on STS-101 Mission

Flames from the solid rocket boosters lit up the clouds of smoke and steam trailing behind shuttle Atlantis on May 19, 2000, as it lifted off on mission STS-101. It was the shuttle program's third space station assembly flight, and first space flight for astronaut Jeff Williams, currently aboard the station as a member of the Expedition 47 crew.

Water Etchings in Western Mexico Sands

Expedition 47 Flight Engineer Tim Kopra of NASA posted this May 15, 2016 photograph to social media, writing, "Water etchings in western @Mexico sands. @Space_Station #Explore"

Stargazing From the International Space Station

Astronauts aboard the International Space Station (ISS) see the world at night on every orbit — that’s 16 times each crew day. An astronaut took this broad, short-lens photograph of Earth’s night lights while looking out over the remote reaches of the central equatorial Pacific Ocean.

Celebrating Ten Years of NASA's Consolidated Space Communications Program

This photograph shows NASA’s newest Deep Space Network antenna, Deep Space Station 35 (DSS-35) in Canberra, Australia. The Deep Space Network is managed by the Space Communications and Navigation (SCaN) program office, created on May 16, 2006.

Hubble Spies a Spiral Snowflake

Together with irregular galaxies, spiral galaxies make up approximately 60 percent of the galaxies in the local universe. However, despite their prevalence, each spiral galaxy is unique — like snowflakes, no two are alike. This is demonstrated by the striking face-on spiral galaxy NGC 6814.

NASA's IceBridge Flies Over the Front of a Greenland Glacier

Operation IceBridge, NASA's airborne survey of polar ice, has returned from the Umanaq B mission along Greenland's western coast. This top-down view from a NOAA P-3 aircraft shows the calving front of Sermeq Kujatdleq glacier. The Naircraft's #2 lower engine nacelle and left main landing gear fairing is in the foreground at top.

Sunset at Big Apple

Full of Science, Dragon Spacecraft Undocks for Return to Earth

ESA astronaut Tim Peake photographed the SpaceX Dragon cargo craft as it undocked from the International Space Station on May 11, 2016. Scheduled to splashdown in the Pacific Ocean at 2:55 p.m. EDT, the spacecraft will return the final batch of human research samples from former NASA astronaut Scott Kelly’s historic one-year mission.

Smoke From Canadian Wildfires Trapped in Clouds

NASA's Aqua satellite captured this image of the clouds over Canada on May 9, 2016. Entwined within the clouds is the smoke billowing up from the wildfires that are currently burning across a large expanse of the country.

Quiet Sunset

Mercury Solar Transit

The planet Mercury is seen in silhouette, lower third of image, as it transits across the face of the sun Monday, May 9, 2016, as viewed from Boyertown, Pennsylvania. Mercury passes between Earth and the sun only about 13 times a century, with the previous transit taking place in 2006.

Hubble Spies the Barred Spiral Galaxy NGC 4394

Shown in this Hubble Space Telescope image, NGC 4394 is the archetypal barred spiral galaxy, with bright spiral arms emerging from the ends of a bar that cuts through the galaxy’s central bulge. These arms are peppered with young blue stars, dark filaments of cosmic dust, and bright, fuzzy regions of active star formation.

Hong Kong City After Raining

May 5, 1961, Alan Shepard in Spacesuit Before Mercury Launch

Astronaut Alan B. Shepard Jr., in his silver pressure suit with the helmet visor closed, prepares for his Mercury Redstone 3 launch on May 5, 1961. Shepard's Freedom 7 Mercury capsule lifted off at 9:34 a.m. and flew a suborbital trajectory lasting 15 minutes and 22 seconds. He became the first American to fly into space.

Neverwinter Nights

Many Fantastic Colors

The Nili Fossae region, located on the northwest rim of Isidis impact basin, is one of the most colorful regions of Mars. This region is ancient and has had a complicated geologic history, leading to interesting structures like layered bedrock, as well as other compositions.

Space Station Flyover of Morocco

Expedition 47 Flight Engineer Jeff Williams of NASA captured this detailed photograph from the International Space Station during a daytime flyover of Morocco on May 2, 2016. Williams shared the image to social media and asked, "Reptile scales, or incredible and rugged geology in Morocco?"

The Dew Drop of Saturn

The water-world Enceladus appears here to sit atop Saturn's rings like a drop of dew upon a leaf. Even though it appears like a tiny drop before the might of the giant Saturn, Enceladus reminds us that even small worlds hold mysteries and wonders to be explored.