On a spacewalk, astronaut Owen K. Garriott, science pilot, retrieves an imagery experiment from the Apollo Telescope Mount attached to the Skylab in Earth orbit in 1973. NASA
Two extremely bright stars illuminate a greenish mist in this image from the Spitzer Space Telescope's 'GLIMPSE360' survey. This mist is comprised of hydrogen and carbon compounds called polycyclic aromatic hydrocarbons, which also are found here on Earth in sooty vehicle exhaust and on charred grills. In space, PAHs form in the dark clouds that give rise to stars. NASA/JPL-Caltech/2MASS/SSI/University of Wisconsin
In late July 2010, flooding caused by heavy monsoon rains began in several regions of Pakistan, including the Khyber Pakhtunkhwa, Sindh, Punjab and parts of Baluchistan. According to the Associated Press, the floods have affected about one-fifth of the country. Tens of thousands of villages have been flooded, more than 1,500 people have been killed, and millions have been left homeless. The floodwaters are not expected to fully recede before late August. NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team
In this 1965 NASA Flight Reserch Center photograph the Lunar Landing Research Vehicle number 1 is shown in flight. When Apollo planning was underway in 1960, NASA was looking for a simulator to profile the descent to the moon's surface. Three concepts surfaced: an electronic simulator, a tethered device, and the ambitious Dryden contribution, a free-flying vehicle. All three became serious projects, but eventually the NASA Flight Research Center's Landing Research Vehicle became the most significant one. NASA Dryden Flight Research Center
To find out what forms matter takes in the Abell 1689 cluster requires not only deep images from telescopes like the Hubble Space Telescope, but detailed computer modeling as well. To start, almost every fuzzy yellow patch in the above image is an entire galaxy. A close inspection, however, shows that many background galaxies are strangely magnified and distorted into long curving arcs by the gravitational lens deflections of the cluster. Computer analyses of the placement and smoothness of these arcs indicate that in addition to the matter in the galaxies you can see, the cluster must also contain a significant amount of dark matter such as the model digitally superposed in purple. NASA, ESA, E. Jullo (JPL), P. Natarajan (Yale), & J.-P. Kneib (LAM, CNRS)
Recent images made with the Wide Field Camera on NASA's Hubble Space Telescope have revealed the structure of a thin sheet of gas located at the edge of the famous 'Great Nebula' in Orion, an estimated 1,500 light years from Earth. Astronomers, who compare the appearance of this sheet of gas with that of a rippled window curtain, report that this emission traces the boundary between the hot, diffuse interior of the nebula and an adjacent dense cool cloud. The sheet is seen in light emitted by atoms of gaseous sulfur (shown in red in the photograph). NASA/JPL
Astronaut L. Gordon Cooper Jr. is hoisted up to a US Navy helicopter during recovery operations in the Atlantic Ocean after the record-setting eight-day Gemini V mission. NASA
A Saturn V first stage is transported by barge down the East Pearl River on its way from Stennis Space Center, then named the National Space Technology Laboratories, to Florida for launch in 1967. NASA
This enhanced-color image was created by combining three images taken through ultraviolet, violet and green filters on July 12, 1981. Several changes were apparent in Saturn's atmosphere since Voyager 1's November 1980 encounter, and the planet's rings had brightened considerably due to the higher sun angle. Voyager 2 was 27 million miles from Saturn when it took this photograph. NASA
The crescent moon rises in the early morning hours shortly before the Soyuz rocket is rolled out to the launch pad, March 24, 2009, at the Baikonur Cosmodrome in Kazakhstan. NASA/Bill Ingalls
At least 60,000 mostly Kurdish refugees have entered Turkey since Thursday after Islamic State militants surrounded a Kurdish stronghold in northern Syria. Some are calling for US airstrikes to stop the group's advance.
ByDominique Soguel, Correspondent
Tens of thousands of Syrians have crossed into Turkey in recent days, fleeing an Islamic State offensive that has opened up another front in Syria's civil war as the US weighs a bombing campaign there.