The moon Tethys floats before the massive, golden-hued globe of Saturn in this natural color view. The thin, dark line of the rings curves around the horizon at top. NASA/JPL/Space Science Institute
As it swooped past the south pole of Saturn's moon Enceladus on July 14, 2005, Cassini acquired high resolution views of this puzzling ice world. From afar, Enceladus exhibits a bizarre mixture of softened craters and complex, fractured terrains. This large mosaic of 21 narrow-angle camera images have been arranged to provide a full-disk view of the anti-Saturn hemisphere on Enceladus. NASA/JPL/Space Science Institute
Astronaut Edward H. White II, pilot for the Gemini-Titan 4 space flight, floats in space during America's first spacewalk. The extravehicular activity was performed during the Gemini 4 mission on June 3, 1965. White spent 23 minutes maneuvering around his spacecraft as Jim McDivitt remained inside the spacecraft. White is attached to the spacecraft by a 25-ft. umbilical line and a 23-ft. tether line, both wrapped in gold tape to form one cord. NASA
This is an artist's concept of a gas giant planet orbiting the cool, red dwarf star Gliese 876, located 15 light-years away in the autumn constellation Aquarius. The planet was discovered in 1998. But new Hubble Space Telescope measurements of the star's wobble, caused by the gravitational tug of the planet, firmly establish the planet's mass as being no more than approximately twice that of Jupiter's. NASA/G. Bacon
This artist's conception depicts the two closely orbiting stars of 44i Bootis. These two stars circle around each other at a rapid rate, passing in front of one another every three hours. CXC/M.Weiss/NASA
The lunar module during the Apollo 11 Mission in 1969, transporting the first humans to walk on the moon. NASA
Saturn's moon Hyperion's crater, Meri, blooms in this extreme color-enhanced view. Meri is overprinted by a couple of smaller craters and displays dark material on its floor that is characteristic of many impact sites on this moon. The walls of craters seen here are noticeably smoother on their sloping sides than around their craggy rims. NASA/JPL/Space Science Institute
Pictured here is a scale prototype of the Echo satellite undergoing a Skin Stress Test on May 1, 1960. The prototype was 12 feet in diameter, with the size being chosen because that was the ceiling height in the NASA Langley model shop. After an unsuccessful launch attempt for the original Echo I satellite, Echo 1A and the follow-on Echo II were successfully launched. The Echo projects were instrumental in letting the world see that the US was a major force in the space race not very far behind Russia. NASA
This image shows the famous Pleiades cluster of stars as seen through the eyes of WISE, or NASA's Wide-field Infrared Survey Explorer. The mosaic contains a few hundred image frames - just a fraction of the more than one million WISE has captured so far as it completes its first survey of the entire sky in infrared light. NASA/JPL-Caltech/UCLA
This illustration shows the relative sizes of the Sun and the Earth by placing them impossibly close together. NASA/JPL-Caltech/R. Hurt
Hardline Islamist insurgents, including the Al Qaeda-linked Nusra Front, now control a second Syrian province after Raqqa, the stronghold of the Islamic State group. But ISIS isn't allied with the Islamists who tookover Idlib.
ByMariam Karouny, Reuters
Islamist groups including Al Qaeda's Nusra Front - but not ISIS - have seized the city of Idlib for the first time in Syria's civil war, fighters and a monitoring group said on Saturday.