The First U.S. Spacewalk – Gemini 4 Ed White made the United States' first spacewalk on June 3, 1965 during the Gemini 4 mission. The extra-vehicular activity (EVA) started at 19:45 UT (3:45 p.m. EDT) on the third orbit when White opened his hatch and used the hand-held manuevering oxygen-jet gun to push himself out of the capsule. (Photo by NASA)

This strange coral-looking specimen is actually a mushroom. The photo, “Beautiful Destroyer”, was taken in the Panamanian tropical rainforest where the mushroom produces nitrogen, an element vital to soil health. (Photo by Sarah A. Batterman)

A selection of work by four photojournalists who have won grants of $10,000 and editorial support from the agency. Here: “Chasing Winter” by Katie Orlinksy. In late summer and early autumn polar bears flock to the native village of Kaktovik in the Alaskan Arctic to eat at “the boneyard” – the remains of whales annually hunted by the community. (Photo by Katie Orlinsky/Getty Images)

Revellers take part in a zombie parade to celebrate Halloween in Kiev, Ukraine, October 31, 2015. (Photo by Valentyn Ogirenko/Reuters)

A dog dressed in a costume takes part in the Pet's Halloween Day parade at El Olivar Park in San Isidro, Lima, October 31, 2015. (Photo by Mariana Bazo/Reuters)

Sisters dressed as the Grady twins from the movie "The Shining" pose for a photo inside their house as they take part in the second edition of "Noche del Terror" (Horror night) during Halloween celebrations in the neighborhood of Churriana, near Malaga, southern Spain, October 31, 2015. (Photo by Jon Nazca/Reuters)

Beluga the bog poses as Britney Spears during the 17th annual Tompkins Square Halloween Dog Parade October 28, 2007 in New York City. The event is the largest dog Halloween party in the United States with an annual attendance of over 400 costumed dogs. (Photo by Mario Tama/Getty Images)

A participant in costume eats a sandwich after a Halloween parade in Kawasaki, south of Tokyo, October 26, 2014. More than 100,000 spectators turned up to watch the parade, where 2,500 participants dressed up in costumes, according to the organiser. (Photo by Yuya Shino/Reuters)