Today, our sun reaches its northernmost point in planet Earth's sky. Called a solstice, the date traditionally marks a change of seasons - from spring to summer in Earth's Northern Hemisphere and from fall to winter in Earth's Southern Hemisphere. In this image from 2007, NASA's Solar Terrestrial Relations Observatory satellites provided the first three-dimensional images of the sun. STEREO, a two-year mission that launched October 2006, provided a unique and revolutionary view of the Sun-Earth System. NASA/JPL-Caltech/NRL/GSFC
This NASA image released on June 21 shows the Aurora Australis Observed from the International Space Station on May 29, 2010. This aurora image is taken during a geomagnetic storm that was most likely caused by a coronal mass ejection from the Sun on May 24. The ISS was located over the Southern Indian Ocean at an altitude of 220 miles, with the astronaut observer most likely looking towards Antarctica (not visible) and the South Pole. AFP PHOTO/NASA/HANDOUT
Some of the coldest and darkest dust in space shines brightly in this infrared image from the Herschel Observatory, a European Space Agency mission with important participation from NASA. The image is a composite of light captured simultaneously by two of Herschel's three instruments - the photodetector array camera and spectrometer with its spectral and photometric imaging receiver. The image reveals a cold and turbulent region where material is just beginning to condense into new stars. ESA/NASA/JPL-Caltech
This image of NGC 6240 contains new X-ray data from Chandra (shown in red, orange, and yellow) that has been combined with an optical image from the Hubble Space Telescope originally released in 2008. In 2002, Chandra data led to the discovery of two merging black holes, which are a mere 3,000 light years apart. They are seen as the bright point-like sources in the middle of the image. Scientists think these black holes are in such close proximity because they are in the midst of spiraling toward each other - a process that began about 30 million years ago. NASA/CXC/MIT/C.Caniz ares/M.Nowak/NASA/STScI
A Russian security officer stands guard as the Soyuz TMA-18 spacecraft is rolled out by train to the launch pad at the Baikonur Cosmodrome, Kazakhstan, on March 31. NASA/Bill Ingalls
This June 10 NOAA handout image shows the MODIS sensor on NASA's Terra satellite as it passed over the Gulf of Mexico at the right time relative to the sun's position, capturing an excellent sunglint image of the region on June 9. Oil can be seen as a shimmering area reflecting the light back into space more vividly than the normal reflectance of water. AFP PHOTO/NOAA/MODIS/NASA
A small, dense object only 12 miles in diameter is responsible for this beautiful X-ray nebula that spans 150 light years. At the center of this image made by NASA's Chandra X-ray Observatory is a very young and powerful pulsar, known as PSR B1509-58, or B1509 for short. The pulsar is a rapidly spinning neutron star which is spewing energy out into the space around it to create complex and intriguing structures, including one that resembles a large cosmic hand. In this image, the lowest energy X-rays that Chandra detects are red, the medium range is green, and the most energetic ones are colored blue. NASA/CXC/CfA/P. Slane et al.
NASA's Spitzer Space Telescope captured this image of comet Holmes in March 2008, five months after the comet suddenly erupted and brightened a millionfold. NASA
In an image grab from video footage released by NASA on June 14, Japan's Hayabusa spacecraft (l.) burns up as it enters Earth's atmosphere as the smaller heat-resistant capsule (r.) released by the spaceprobe streaks ahead toward Earth to land in the Australian Outback. AFP/NASA
This illustration shows the approximate size of Earth compared to the Sun. The giant coronal mass ejection in the image blasted off the Sun in October 2003. The image was taken by the international SOHO spacecraft. NASA/ESA
Behind a low, unobtrusive brick building on Boston’s Lenox Street is a lush, green forest. Brown and silver-gray trees cover the building’s wall, their leafy canopies blocking the sky. Sun-dappled stones sit on tangles of grass. A boy perches on the largest rock, gazing at a distant meadow.