May 20, 2012 (36 images)

Officers stand by after protestors clashed with police outside of the 2012 NATO Summit at the McCormick Place convention center in Chicago, May 20, 2012. Approximately 20,000 protestors marched on NATO's biannual summit in the largest. UPI/Mark Cowan

Afghanistan president Hamid Karzai (L) talks with US President Barack Obama before the start of the 2012 NATO Summit on May 20, 2012 in Chicago. World leaders are participating the the two-day event to discuss international security and issues related to Afghanistan. UPI/Shawn Thew/Pool

The Sun is partially covered by the Moon as it settles into the horizon in this image of the Solar Eclipse as viewed from Sky Harbor Airport in Phoenix, Arizona on May 20, 2012. The Sun was not fully covered in Phoenix as it was in other parts of the Southwestern United States. UPI/Art Foxall

Singer Justin Bieber arrives at the 2012 Billboard Music Awards, held at the MGM Grand Hotel in Las Vegas, Nevada on May 20, 2012. UPI/Jim Ruymen