Astronaut Stephen K. Robinson, STS-114 mission specialist, anchored to a foot restraint on the International Space Station's Canadarm2, participates in the mission's third session of extravehicular activity on August 3, 2005. NASA
This artist's concept depicts a supermassive black hole at the center of a galaxy. NASA's Galaxy Evolution Explorer found evidence that black holes, once they grow to a critical size, stifle the formation of new stars in elliptical galaxies. Black holes are thought to do this by heating up and blasting away the gas that fuels star formation. The blue color here represents radiation pouring out from material very close to the black hole. NASA/JPL-Caltech
What makes the core of galaxy MCG-6-30-15 so bright? Some astronomers believe the answer is a massive spinning black hole. If so, this would be the first observational indication that it is possible to make a black hole act like a battery and tap into its rotational energy. Pictured is an artist's illustration of a black hole surrounded by an accretion disk. XMM-Newton/ESA/NASA
Prior to installation, technicians inspect the primary mirror of the Hubble Space Telescope (HST). The first in a series of great observatories launched by NASA, the HST was designed to last approximately 15 years, but is still being used today. NASA
Astronaut John H. Glenn Jr. looks into a Celestial Training Device (globe) during training in the Aeromedical Laboratory at Cape Canaveral, Florida. NASA
Tycho's Supernova, the red circle visible in the upper left part of the image, is a remnant of a star explosion. It is named after the astronomer Tycho Brahe, although he was not the only person to observe and record the supernova. When the supernova first appeared in November 1572, it was as bright as Venus and could be seen in the daytime. NASA/JPL-Caltech/UCLA
The Soyuz 15 approaches the International Space Station, carrying NASA astronauts and cosmonauts in Oct. 2007. NASA
The 'bull's-eye' of the Richat Structure in the barren Gres de Chinguetti Plateau, central Mauritania in northwest Africa is featured in this image photographed by an Expedition 15 crewmember on the International Space Station. It represents domally uplifted, layered (sedimentary) rocks that have been eroded by water and wind into the present shape. The 25-mile-wide structure is a 300-foot-deep landmark that has caught the eye of many an astronaut in Earth orbit. NASA
On its way to a 2014 rendezvous with comet 67P/Churyumov-Gerasimenko, the European Space Agency's Rosetta spacecraft, with NASA instruments aboard, flew past asteroid Lutetia on July 10. The instruments aboard Rosetta recorded the first close-up image of the biggest asteroid so far visited by a spacecraft. Rosetta made measurements to derive the mass of the object, understand the properties of the asteroid's surface crust, record the solar wind in the vicinity and look for evidence of an atmosphere. ESA 2010 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA
The night side of Saturn's moon Rhea shines softly in reflected light from Saturn. A similar effect, called Earthshine, can often be seen dimly illuminating the dark side Earth's moon. Background stars make short, dim trails across the black sky. The sunlit terrain on Rhea is so much brighter than the part lit by Saturn that the former is completely overexposed in this view, which took more than 30 seconds to acquire. NASA/JPL/Space Science Institute
Chilean authorities had issued an orange alert on Monday because of increased activity at the volcano.
ByEva Vergara and Gabriela Ulloa, Associated Press
One of South America's most active volcanoes erupted early Tuesday in southern Chile, spewing heavy smoke into the air as lava surged down its slopes, prompting authorities to evacuate thousands of people.