The Cat's Eye Nebula, NGC 6543, located in the constellation of Draco, is seen in this undated image. X-ray: NASA/UIUC/Y.Chu et al., Optical: NASA/HST
Astronaut Leroy Chiao, Expedition 10 commander and NASA ISS science officer, watches a water bubble float between him and the camera, showing his image refracted, on the International Space Station in January 2005. NASA
This picture of Neptune was produced from the last whole-planet images taken through the green and orange filters on the Voyager 2 narrow angle camera. The images were taken at a range of 4.4 million miles from the planet, 4 days and 20 hours before closest approach in 1990. NASA/JPL
Io is a colorful place. The closest large moon of Jupiter, Io is the most volcanic moon in the Solar System with its surface being completely buried in volcanic lava every few thousand years. The black and red material corresponds to the most recent volcanic eruptions and is probably no more than a few years old. This image by the automated spacecraft Galileo highlights the side of Io that always faces away from Jupiter. Galileo Mission, JPL, NASA
The Orion Nebula is a 'happening' place where stars are born and this colony of hot, young stars is stirring up the cosmic scene in this image from NASA's Spitzer Space Telescope. The young stars dip and peak in brightness; shifting cold and hot spots on the stars' surfaces cause brightness levels to change. In addition, surrounding disks of lumpy planet-forming material can obstruct starlight. NASA/JPL-Caltech
While perhaps not quite as well known as its star formation cousin of Orion, the Corona Australis region (containing, at its heart, the Coronet cluster) is one of the nearest and most active regions of ongoing star formation. The Spitzer image shows young stars plus diffuse emission from dust. NASA/JPL-Caltech/CfA
This picture of unidentified possible small debris was recorded with a digital still camera by astronaut Daniel Burbank onboard the Space Shuttle Atlantis. NASA
European Space Agency astronaut Thomas Reiter (r.), STS-116 mission specialist, plays a guitar in the Unity node of the International Space Station. Cosmonaut Mikhail Tyurin, Expedition 14 flight engineer representing Russia's Federal Space Agency is seen with him. NASA
Space Shuttle Discovery's underside is featured in this image photographed by astronaut Stephen K. Robinson, STS-114 mission specialist, during extravehicular activities in 2005. Robinson's shadow is visible on the thermal protection tiles. NASA
The eye of Hurricane Ivan, swirling with sustained winds of 160 mph at the time, was photographed as the storm entered the Gulf of Mexico on Sept. 13, 2004 by astronaut Edward M. (Mike) Fincke, 230 miles above the Earth aboard the International Space Station. NASA
Experts remain skeptical of whether the country is prepared for potential post-election violence. Meanwhile, Nigerian officials have confirmed that hundreds of civilians have been kidnapped by Boko Haram extremists.
ByVincent Nwanma, Correspondent
With Saturday's presidential election in Nigeria looming, armored vehicles and rifle-toting police have surrounded the offices of the electoral commission in a Lagos suburb, while police checkpoints are multiplying along Ikorodu Road, the bustling city’s main thoroughfare.