The government of North Korea conducts its fifth and reportedly biggest nuclear test. World leaders condemn the act, with South Korea calling it "maniacal recklessness".

Elizabeth II becomes the longest reigning monarch of the United Kingdom.

The album Songs of Innocence by U2 is digitally released at no charge to all customers of the iTunes Music Store, appearing automatically in the "purchased" section of over 500 million users worldwide.

The Indian space agency puts into orbit its heaviest foreign satellite yet, in a streak of 21 consecutive successful PSLV launches.

The Dubai Metro, the first urban train network in the Arabian Peninsula, is ceremonially inaugurated.

In Kentucky's Mammoth Cave National Park, a Cave Research Foundation exploration and mapping team discovers a link between the Mammoth and Flint Ridge cave systems, making it the longest known cave passageway in the world.