NASA's Swift satellite views Comet Lulin as it made its closest approach to Earth in February 2009. Lulin, like all comets, is a clump of frozen gases mixed with dust. These 'dirty snowballs' cast off gas and dust whenever they venture near the sun. Comet Lulin, which is formally known as C/2007 N3, was discovered in 2008 by astronomers at Taiwan's Lulin Observatory. Lulin passed closest to Earth -- 38 million miles, or about 160 times farther than the moon -- late on the evening of Feb. 23, 2009, for North America. NASA, Swift, Univ. Leicester, DSS (STScI/AURUA), Dennis Bodewits
On July 11, the new moon passed directly in front of the sun, causing a total solar eclipse in the South Pacific. In this image, the solar eclipse is shown in gray and white from a photo provided by the Williams College Expedition to Easter Island and was embedded with an image of the sun’s outer corona taken by the Large Angle Spectrometric Coronagraph (LASCO) on the SOHO spacecraft and shown in red false color. NASA/ESA/Williams College Eclipse Expedition
The surface of Saturn's moon Dione is rendered in crisp detail against a hazy, ghostly Titan. The image was taken in visible blue light with the Cassini spacecraft narrow-angle camera on April 10. NASA/JPL/Space Science Institute
In December 2004, a neutron star flared up so brightly, it temporarily blinded all the x-ray satellites in space, and lit up the Earth's upper atmosphere. This tremendous blast of energy was from a giant flare created by the neutron star's twisting magnetic field. Objects like this are called magnetars, and they produce magnetic fields trillions of time more powerful than those here on Earth. These fields are so strong they can actually buckle the surface of the neutron star causing these powerful star quakes. NASA
This observation from NASA's Mars Reconnaissance Orbiter shows the floor of a large impact crater in the southern highlands, north of the giant Hellas impact basin. NASA/JPL-Caltech/University of Arizona
This is a composite image of NGC 1068. It is located about 50 million light years from Earth and contains a supermassive black hole about twice as massive as the one in the middle of the Milky Way Galaxy. X-ray (NASA/CXC/ MIT/C.Canizares, D.Evans et al), Optical (NASA/STScI), Radio (NSF/ NRAO/VLA)
This mosaic of images from the Wide-Field Infrared Survey Explore, or WISE, in the constellation of Cassiopeia contains a large star-forming nebula within the Milky Way Galaxy, called IC 1805 or the Heart Nebula, a portion of which is seen at the right of the image. NASA/JPL-Caltech/UCLA
Aurora Australis (curtain form) viewed from Space Shuttle Endeavour, part of which can be seen in bottom left foreground in this April 1994 photo. NASA/File
Scientists on the sea ice in the Chukchi Sea off the north coast of Alaska disperse equipment on July 4, as they prepare to collect data on and below the ice. The research is part of NASA's ICESCAPE mission aboard the U.S. Coast Guard icebreaker Healy to sample the physical, chemical and biological characteristics of the ocean and sea ice. NASA/Kathryn Hansen
Taken in 1989 by Voyager 2, this is a global color mosaic of Triton. With a radius about 22 percent smaller than Earth's moon, Triton is the largest satellite of Neptune and is one of the few bodies in the solar system known to have a nitrogen-dominated atmosphere. NASA/JPL/USGS
The number of tourists coming to Japan dropped dramatically after the Fukushima nuclear disaster in 2011. But between the weak currency and fading memories of the disaster, tourism saw a record high last month.
Tourists have stayed away in droves in the two years since a deadly triple disaster on Japan's northeast coast, but Japan is mounting a remarkable comeback, with foreign visitor numbers reaching a record high last month.