A halo appears around the moon in Kvæfjord, Troms, Norway, on Feb. 19, 2013. Such halos occur when moonlight is refracted by ice crystals in the atmosphere.
•More photos by Steve Nilsen
A cloud over the Sahara Desert - and its shadow - are seen from the International Space Station on Feb. 17. "There is an undeniable beauty in human imagination," Hadfield wrote in a Twitter tweet. "What do you see in this Saharan cloud?"
The trail of a meteor is seen over Chelyabinsk, Russia, on Feb. 15. The meteor streaked across the sky and blew up, releasing as much energy as an atomic bomb and setting off a shock wave. About 1,200 people were injured, most of them by flying glass from broken windows.
This Chandra X-Ray Observatory image, obtained Feb. 26, shows a highly distorted supernova remnant that may contain the most recent black hole formed in the Milky Way galaxy. The color-coded composite image of the supernova remnant W49B combines X-rays from Chandra (blue and green), radio data from the Very Large Array (pink) and infrared data from the Palomar Observatory (yellow).
Russian cosmonaut Alexander Samoukutyaev prepares to descend into a swimming pool in a spacesuit as part of a training session at the cosmonaut training facility in Star City, outside Moscow, on Feb. 13. Samoukutyaev, cosmonaut Elena Serova and NASA astronaut Barry Wilmore are preparing for a mission to the International Space Station in October 2014.
Comet PanSTARRS glows with a fanlike tail in this image captured by Argentine astrophotographer Ignacio Diaz Bobillo on Feb. 15. The comet is expected to reach naked-eye visibility in the Northern Hemisphere in early March.
Italy’s Mount Etna erupts in a Feb. 19 image from NASA's Earth Observing-1 (EO-1) satellite. Each outburst, or paroxysm, produces an “emission of lava flows, pyroclastic flows, lahars and an ash cloud,” according to the Italian Istituto Nazionale di Geofisica e Vulcanologia.
This self-portrait of NASA's Curiosity rover combines dozens of exposures taken by the rover's Mars Hand Lens Imager on Feb. 3. The rover was positioned at a patch of flat outcrop called "John Klein," the site for the first rock-drilling activities by Curiosity. Because of the process by which the pictures were taken, the rover's robotic arm is not visible in the mosaic.
Arid fingers of sand-blasted rock look as if they're barely holding on against the hot Saharan wind in this view captured from the International Space Station on Feb. 20.
Generations of stars glitter in a color-coded infrared portrait from NASA's Spitzer Space Telescope, released Feb. 14. In this wispy star-forming region, called W5, the oldest stars can be seen as blue dots in the centers of the two hollow cavities. The other blue dots are stars not associated with the region. Red shows heated dust that pervades the region's cavities, while green highlights dense clouds.
Russian spacewalkers Oleg Kononenko, left, and Anton Shkaplerov work on the exterior of the International Space Station on Feb. 16.
The planet Mercury takes on exaggerated hues in this NASA photo, released Feb. 22. The false-color picture was produced using data from the Messenger mission's color base map imaging campaign. The colors enhance the chemical, mineralogical and physical differences in the rocks that make up Mercury's surface.
Magnetic loops rise from the sun's surface, as seen in an image captured by NASA's Solar Dynamics Observatory. Such loops lie at the heart of eruptions on the sun known as coronal mass ejections, or CMEs. The image was captured on July 19, 2012, and released to the public on Feb. 20, 2013.
Siberia's Lake Baikal is spread out beneath the International Space Station in a Feb. 26 image. Immensely old and deep, the lake holds one-fifth of Earth's fresh water. The space station's solar panels can be seen at the right edge of the picture.
Canadian Darryl Archer begins observing celestial objects during the first evening of the six-day Winter Star Party on Scout Key, Fla, on Feb. 4. About 500 amateur and professional astronomers were in the lower Florida Keys to observe southern constellations, stars, planets and even the International Space Station. The Keys' southern location, clear night skies and observing locations, void of bright city lights, create optimal viewing conditions.
Morning clouds cast shadows off the coast of China on Feb. 9, in this view from the International Space Station.
An image from the European Southern Observatory, released Feb. 4, shows the intricate structure of part of the Seagull Nebula, also known as IC 2177. These wisps of gas and dust form part of the "wings" of the celestial bird. This new view of the region was captured by the Wide Field Imager on the MPG/ESO 2.2-meter telescope at the ESO's La Silla Observatory in Chile.
A Southwest Airlines jet is silhouetted against the rising full moon as it takes off from Phoenix's Sky Harbor Airport on Feb. 24.
An image of the spiral galaxy M106, released Feb. 5, combines Hubble Space Telescope observations with additional data from amateur astronomers Robert Gendler and Jay GaBany. Located a little more than 20 million light-years away, M106 is one of the brightest and nearest spiral galaxies to our own.
June Scobee Rodgers, widow of Challenger commander Dick Scobee, and NASA Administrator Charles Bolden visit the Space Shuttle Columbia Memorial during a wreath-laying ceremony that was part of the agency's Day of Remembrance at Arlington National Cemetery on Feb. 1. The day was set aside to honor astronauts who lost their lives in the line of duty, including the victims of the Apollo 1, Challenger and Columbia tragedies. Feb. 1, 2013, marked the 10th anniversary of Columbia's loss.