Although Tethys and Janus both orbit Saturn and are both made of more or less the same materials, they are very different worlds. via NASA http://ift.tt/1RftqBR

The distinctive blue bubble appearing to encircle WR 31a is a Wolf–Rayet nebula — an interstellar cloud of dust, hydrogen, helium and other gases. Created when speedy stellar winds interact with the outer layers of hydrogen ejected by Wolf–Rayet stars, these nebulae are frequently ring-shaped or spherical. via NASA http://ift.tt/1oEvGez

NASA research mathematician Katherine Johnson is photographed at her desk at Langley Research Center in 1966. Johnson made critical technical contributions during her career of 33 years, which included calculating the trajectory of the 1961 flight of Alan Shepard. She was awarded the Presidential Medal of Freedom on Nov. 24, 2015. via NASA http://ift.tt/1QgSqsn

Expedition 46 crew member Tim Peake of the European Space Agency (ESA) shared a stunning image of a glowing aurora taken on Feb. 23, 2016, from the International Space Station. Peake wrote, “The @Space_Station just passed straight through a thick green fog of #aurora…eerie but very beautiful. #Principia” via NASA http://ift.tt/1Qyiuyk

This image, acquired by the Operational Land Imager (OLI) on Landsat 8, shows the glaciers of Sierra de Sangra on Jan. 14, 2015. Snow and ice are blue in these false-color images, which use different wavelengths to better differentiate areas of ice, rock, and vegetation. via NASA http://ift.tt/1T4g2qg

Three of Saturn’s moons — Tethys, Enceladus and Mimas — are captured in this group photo from NASA’s Cassini spacecraft. via NASA http://ift.tt/1PSmkVP

This image, acquired on Nov. 24, 2015 by the High Resolution Imaging Science Experiment (HiRISE) camera aboard NASA’s Mars Reconnaissance Orbiter, shows the western side of an elongated pit depression in the eastern Noctis Labyrinthus region of Mars. Along the pit’s upper wall is a light-toned layered deposit. via NASA http://ift.tt/1VsgGvb

On Sept. 12, 1992, launch day of the STS-47 Spacelab-J mission on space shuttle Endeavour, NASA astronaut Mae Jemison waits as her suit technician, Sharon McDougle, performs a unpressurized and pressurized leak check on her spacesuit at the O&C Building at Kennedy Space Center. Dr. Jemison was the first African-American woman to fly in space. via NASA http://ift.tt/1UawQLh

Engineers from NASA’s Langley Research Center and Boeing dropped a full-scale test article of the company’s CST-100 Starliner into Langley’s 20-foot-deep Hydro Impact Basin. Although the spacecraft is designed to land on land, Boeing is testing the Starliner’s systems in water to ensure astronaut safety in the unlikely event of an emergency. via NASA http://ift.tt/218F5cG

Zinnia plants from the Veggie ground control experiment at NASA’s Kennedy Space Center in Florida were harvested Feb. 11 in the same way that crew member Scott Kelly will harvest the zinnias growing in the Veggie system aboard the International Space Station on Feb. 14—Valentine’s Day. via NASA http://ift.tt/247LgjK