This view from the International Space Station shows the sun heading toward the horizon over southwestern Australia on April 2, 2013. The space station's solar panels loom in the foreground.
The Horsehead Nebula takes on an eerie glow in an infrared image from the Hubble Space Telescope. This picture, released April 21, marks the 23rd anniversary of the famous observatory's launch in 1990 aboard the space shuttle Discovery.
Italian astronaut Luca Parmitano (right), NASA astronaut Karen Nyberg (left) and Russian cosmonaut Fyodor Yurchikhin get their picture taken inside a Soyuz capsule simulator during a training exercise at Russia's Star City complex outside Moscow on April 26. The three spacefliers are scheduled to head for the International Space Station in May.
This full-disk view of the sun was captured by NASA's Solar Dynamics Observatory on April 11, during the strongest solar flare yet seen in 2013. The colors reflect the intensity of emissions in extreme ultraviolet wavelengths.
Mountain ridges near San Alberto in Mexico look like a reptilian eye in this view from the International Space Station. Canadian astronaut Chris Hadfield uses a different metaphor: "A Dali watch on an alligator wristband." The picture was taken on April 15 and shared via social media on April 25.
A Russian Soyuz rocket blasts away from its launch pad at the Baikonur Cosmodrome in Kazakhstan on March 29, sending NASA astronaut Chris Cassidy and Russian crewmates Pavel Vinogradov and Alexander Misurkin toward the International Space Station for their six-month orbital tour of duty.
Children hold self-made rocket models during a show in front of the Peter and Paul Fortress in St. Petersburg, Russia, on April 14. The gathering was part of the festivities surrounding Cosmonautics Day on April 12. The Russian holiday marks the anniversary of Soviet cosmonaut Yuri Gagarin's historic spaceflight in 1961 - an occasion marked in other countries as "Yuri's Night."
Geological formations take on an alien look in a picture of the southern Sahara in Mauritania, taken on March 19 from the International Space Station and shared via social media on April 24. Canadian astronaut Chris Hadfield calls the scene "effortless natural art."
This glittering picture shows X-ray emissions from young sunlike stars in the "wing" of the Small Magellanic Cloud, a satellite galaxy associated with the larger Milky Way. The Small Magellanic Cloud lies about 180,000 light-years from Earth. In this April 4 picture, readings from the Chandra X-ray Observatory are shown in purple; visible light seen by the Hubble Space Telescope is in red, green, and blue; and infrared readings from the Spitzer Space Telescope are indicated in red.
This image from the high-resolution camera on NASA's Mars Reconnaissance Orbiter shows a relatively youthful crater with dark-rayed ejecta, plus a light-toned zone that extends beyond that ejecta. The picture was taken in 2009, but it was released along with other images from the High Resolution Imaging Science Experiment, or HiRISE, on April 3, 2013. Watch a video about the crater
Orbital Sciences Corp.'s Antares rocket rises for the first time from its launch pad on April 21 at the Mid-Atlantic Regional Spaceport on Wallops Island, Va. This practice launch was aimed at testing the rocket for what's expected to be regular cargo deliveries to the International Space Station
An image from NASA's Terra satellite shows a thick plume of dust blowing over the eastern Mediterranean Sea on April 1. The clouds spread over Israel, the West Bank, Cyprus and Turkey in a giant, counterclockwise arc.
A March 27 photo from the European Southern Observatory shows the bright open star cluster NGC 2547, as seen by the Wide Field Imager on the MPG/ESO 2.2-meter telescope at the La Silla Observatory in Chile. Many remote galaxies can be seen between the bright stars, far away in the background of the image.
Launch crew members check NASA astronaut Chris Cassidy's spacesuit just before his March 28 launch to the International Space Station. Russian cosmonauts Pavel Vinogradov and Alexander Misurkin joined Cassidy in a Soyuz capsule for a quick six-hour ride to the station.
Virgin Galactic's SpaceShipTwo lights up its rockets for the first time in flight on April 29. Afterward, the company said in a tweet that the pilots confirmed "SpaceShipTwo exceeded the speed of sound on today's flight!" The reported maximum velocity was Mach 1.2. Virgin Galactic plans to send paying passengers on suborbital space trips on a regular basis.
An enormous stellar nursery known as W3 shines in infrared light, as shown in a March 27 image from the European Space Agency's Herschel space observatory. W3 lies about 6,200 light-years away in the Perseus Arm, one of the Milky Way galaxy's main spiral arms. In this image, low-mass stars are seen as tiny yellow dots embedded in cool red filaments. In contrast, high-mass stars emit intense radiation that heats up the gas and dust around them. Those hot regions are shown here in blue.
The rugged landscape of Iytwelepenty/Davenport Murchison National Park in the Australian Outback is "crazily beautiful" when seen from outer space, Canadian astronaut Chris Hadfield says. Hadfield sent down this picture from the International Space Station on April 21.
Comet ISON takes on a fuzzy glow in an April 10 image from the Hubble Space Telescope. This picture was taken when the comet was 394 million miles from Earth, but Comet ISON is expected to get much closer. Some skywatchers hope it will become bright enough to rank as the "Comet of the Century."