Lightning flashes from a storm cloud to strike the ground. Such bolts represent only a small part of the overall phenomenon of lightning. http://www.nasa.gov/sites/default/files/thumbnails/image/3_iss057e055409.jpg

The stars of the globular cluster NGC 6441 sparkle peacefully in the night sky, about 13,000 light-years from the Milky Way’s galactic center. http://www.nasa.gov/sites/default/files/thumbnails/image/potw2022a.jpg

Exquisite layering is revealed emerging from the sand in southern Holden Crater. Sequences like these offer a window into Mars' complicated geologic history. http://www.nasa.gov/sites/default/files/thumbnails/image/pia23952.jpg

Japan's resupply ship, the H-II Transfer Vehicle-9 (HTV-9), is pictured attached to the International Space Station's Harmony module. http://www.nasa.gov/sites/default/files/thumbnails/image/iss063e024519.jpg

Like a wisp of green smoke, the aurora australis seemingly intersects with the Earth's airglow as the International Space Station orbited above the Indian Ocean halfway between Australia and Antarctica. http://www.nasa.gov/sites/default/files/thumbnails/image/iss063e025120.jpg

This illustration imagines the view from NASA's Cassini spacecraft during one of its final dives between Saturn and its innermost rings. http://www.nasa.gov/sites/default/files/thumbnails/image/pia22768.jpg

Looking deep into the universe, the Hubble Space Telescope catches a passing glimpse of the numerous arm-like structures that sweep around this barred spiral galaxy, known as NGC 2608. Appearing as a slightly stretched, smaller version of our Milky Way, the peppered blue and red spiral arms are anchored together by the prominent horizontal http://www.nasa.gov/sites/default/files/thumbnails/image/potw2023a.jpg

Launched on April 20, 2004, Gravity Probe B (GP-B) was a collaboration between Stanford University and NASA designed to test two previously untested aspects of Albert Einstein’s general theory of relativity. http://www.nasa.gov/sites/default/files/thumbnails/image/gpb.jpg

Seen here in incredible detail is the starburst galaxy formally known as PLCK G045.1+61.1. The galaxy, which appears as multiple reddish dots near the center of the image, is being gravitationally lensed by a cluster of closer galaxies, also seen in the image. http://www.nasa.gov/sites/default/files/thumbnails/image/potw2024a_0.jpg

This artist's concept shows an astronaut on Mars, as viewed through the window of a spacecraft. http://www.nasa.gov/sites/default/files/thumbnails/image/pia23900.jpg

Pilots Troy Asher and Wayne Ringelberg walk out of NASA’s Armstrong Flight Research Center’s (AFRC) hangar in Palmdale, California, toward the flight line. http://www.nasa.gov/sites/default/files/thumbnails/image/afrc2020-0063-15_orig.jpg

Pilots Troy Asher and Wayne Ringelberg walk out of NASA’s Armstrong Flight Research Center’s (AFRC) hangar in Palmdale, California, toward the flight line. http://www.nasa.gov/sites/default/files/thumbnails/image/afrc2020-0063-15_orig.jpg

Astronomers have discovered evidence for thousands of black holes located near the center of our Milky Way galaxy using data from NASA's Chandra X-ray Observatory. http://www.nasa.gov/sites/default/files/thumbnails/image/sgra_swarm_lg.jpg

NASA astronauts (from top) Chris Cassidy and Bob Behnken work on U.S. spacesuits. http://www.nasa.gov/sites/default/files/thumbnails/image/iss063e030609.jpg

In this image NGC 7027 resembles a jewel bug, an insect with a brilliantly colorful metallic shell. http://www.nasa.gov/sites/default/files/thumbnails/image/stsci-h-p2031d-f-1764x1249.png

On June 21, 2020, as the International Space Station orbited over Kazakhstan and into China, an external high-definition camera captures this picture of the solar eclipse shadowing a portion of the Asian continent. http://www.nasa.gov/sites/default/files/thumbnails/image/iss063e031761.jpg

This composite image, made from six frames, shows the International Space Station, with a crew of five onboard, in silhouette as it transits the Sun. http://www.nasa.gov/sites/default/files/thumbnails/image/50041214891_87bdab628c_o.jpg

We don’t see the beautiful spiral arms of galaxy NGC 5907 in this Hubble image because we are viewing it edge-on, like looking at the rim of a plate. It is for this reason that NGC 5907 is also known as the Knife Edge galaxy. http://www.nasa.gov/sites/default/files/thumbnails/image/potw2025a.jpg

Spacewalkers Bob Behnken (left) and Chris Cassidy (right) in the Quest Airlock on June 26, 2020, before beginning a spacewalk to replace batteries on one of two power channels on the International Space Station. http://www.nasa.gov/sites/default/files/thumbnails/image/ebir4gdxsaqaxnu.jpg

June 30 is Asteroid Day. http://www.nasa.gov/sites/default/files/thumbnails/image/2166_ds1palomar_opt.jpg