The 26th annual National Geographic Traveler Photo Contest is now accepting submissions. Official categories include: “Travel Portraits”, “Outdoor Scenes”, “Sense of Place” and “Spontaneous Moments”. The contest is accepting entries until June 30. Photo: “Forest lights”. Aurora Borealis over the forest of the Pyhae Luosto National Park, Finland. (Photo and caption by Nicholas Roemmelt/National Geographic Traveler Photo Contest)

A general view of Hong Kong's business district is seen Thursday, August 1, 2013. (Photo by Vincent Yu/AP Photo)

Apollo 9 Command/Service Modules (CSM) nicknamed “Gumdrop” and Lunar Module (LM), nicknamed “Spider” are shown docked together as Command Module pilot David R. Scott stands in the open hatch. Astronaut Russell L. Schweickart, Lunar Module pilot, took this photograph of Scott during his EVA as he stood on the porch outside the Lunar Module. Apollo 9 was an Earth orbital mission designed to test docking procedures between the CSM and LM as well as test fly the Lunar Module in the relative safe confines of Earth orbit. (Photo by NASA)

A 19-year-old Japanese macaque monkey named Monday sneezes while suffering an allergy to pollen from the cedar tree, at Awajishima Monkey Center on March 26, 2012 in Sumoto, Hyogo, Japan. Some twenty monkeys are suffering the effects of hay fever at this time of the year, with the typical symptoms being the same as with humans. (Photo by Buddhika Weerasinghe/Getty Images)

Studio stack: Rabbit? Acanthocinus aedilis, Cerambycidae, A female Timberman (Timbermam perhaps?). Stacked from 216 exposures in Zerene Stacker (PMAX). (Photo by John Hallmén). P.S. All pictures are presented in high resolution.

An Indian Brahmin and his family. (Photo by Hulton Archive/Getty Images). Circa 1890

A tiger cub has a short chat with a chimp. (Photo by Ian Tyas/Keystone Features/Getty Images). 27th November 1979

Festival-goers enjoy on Shipyard Island, the venue of the 24th Sziget (Island) Festival in Northern Budapest, Hungary, 12 August 2016. The festival is one of the biggest cultural events of Europe presenting art exhibitions, theatrical and circus performances and music concerts. (Photo by Polyák Attila/Origo.hu)