- Passenger services begin on the 54-kilometre (34 mi) Moscow Central Circle rail line.
- North Korea conducts its fifth and largest nuclear test to date.
- NASA launches OSIRIS-REx (artist's impression pictured), a probe sent to return samples from the asteroid 101955 Bennu.
- Genetic analysis shows that the giraffe genus, previously thought to contain one extant species, actually consists of four.
- The Summer Paralympics open in Rio de Janeiro, Brazil.
- The IUCN reclassifies the giant panda as a vulnerable species, and the eastern gorilla as critically endangered.