A star cluster in the heart of the Flame Nebula, known as NGC 2024, glows in a May 8 image that combines data from NASA's Chandra X-Ray Observatory and Spitzer Space Telescope. Chandra's X-ray view is shown in purple, while red, green and blue hues add Spitzer's perspective in infrared wavelengths. The star cluster is about 1,400 light-years from Earth in the constellation Orion.
Star trails circle the celestial south pole over a cactus-dominated landscape in Chile's Atacama Desert, in a long-exposure image released by the European Southern Observatory on May 12. The trails show the apparent path of stars in the sky as Earth slowly rotates. A deeper exposure was superimposed over the magnificent trails, revealing fainter stars and the southern Milky Way.
Japanese astronaut Koichi Wakata peers out one of the windows of the Cupola on the International Space Station on April 27. A crewmate inside the Russian-built Pirs docking module captured the image. The Cupola is considered the station's best vantage point for Earth observation.
Dust rises near the Russian Soyuz TMA-11M space capsule, shortly after its landing in Kazakhstan on May 14. Three astronauts, representing Russia, Japan and the United States, touched down safely in the Soyuz capsule after making their descent from the International Space Station.
A Russian recovery team helps Japanese astronaut Koichi Wakata come down from the hatch of a Soyuz capsule on May 14, after Wakata and two crewmates landed in Kazakhstan to end their months-long tour of duty on the International Space Station.
A composite view, created from several images, shows several Camelopardalid meteors emanating from their radiant point above Rondeau Provincial Park in Ontario early on May 24. The highlight of the image is the long bright streak, which captures the passage of the International Space Station through the sky during a long-exposure opportunity. "The ISS transit was quite a surprise," photographer Malcolm Park told NBC News.
The fifth brightest galaxy in the sky, Centaurus A, glitters in a "pro-am" picture released by NASA on April 23. The image was produced by combining amateur astronomical observations with X-ray data from NASA's Chandra X-Ray Observatory. Centaurus A is an active galaxy, about 12 million light-years from Earth.
German astronaut Alexander Gerst, Russian cosmonaut Maxim Suraev and NASA astronaut Reid Wiseman share a laugh during a May 6 session at the Star City cosmonaut training complex outside Moscow. A Russian Soyuz craft sent the three spacefliers to the International Space Station on May 29.
NASA astronaut Reid Wiseman makes a heart shape with his hands as he bids farewell to his relatives from a bus window on May 28, during a sending-off ceremony at the Baikonur Cosmodrome in Kazakhstan. Wiseman and two crewmates were launched from Baikonur to the International Space Station early on May 29.
Spectators watch as a Russian Soyuz rocket sends three spacefliers up to the International Space Station from the Baikonur Cosmodrome in Kazakhstan on May 29. The three men - Russia's Maxim Suraev, Germany's Alexander Gerst and NASA's Reid Wiseman - are due to spend five and a half months in orbit.
Spectators look on as huge handmade rockets are launched during the Bun Bang Fai festival on May 11 in Yasothon, Thailand. The rocket festival celebrates the beginning of the rainy season.
Dark clumps in a massive cloud of gas and dust, 16,000 light-years from Earth, are documented in this May 22 infrared image from NASA's Spitzer Space Telescope. The densest, darkest clumps are expected to blossom eventually into powerful stars, known as O-type stars, the formation of which has long puzzled scientists. Other colors in the star-forming region, known as Infrared Dark Cloud G028.37+00.07, reflect different infrared wavelengths.
This view of Mars' 67-mile-wide Rabe Crater, based on observations by the European Space Agency's Mars Express orbiter and released on May 15, reveals a dark-colored, intricately shaped dune field. The dunes are probably made up of eroded sediments that have been shaped by the prevailing winds. Smaller craters in the region also contain these dark deposits.
A jetliner leave a vapor trail as it passes in front of the moon on May 20, as seen from the Algerian capital Algiers.
• See last month's space slideshow