A woman mourns near a gravestone today at a ceremony in Kyiv
People in Ukraine, Belarus and other countries are today commemorating the 19th anniversary of the Chornobyl nuclear disaster. In the early hours of 26 April 1986, a massive chemical explosion blew the 1,000-ton cover off the top of Chornobyl's Unit Four reactor, spewing radiation over Ukraine, Belarus, and northern Europe. Millions of people were affected by the disaster north of Kyiv.