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)

A costumed guest attends WonderCon Anaheim 2015 at Anaheim Convention Center on April 4, 2015 in Anaheim, California. (Photo by Araya Diaz/WireImage)

The Bridge “Rakotzbrücke” is pictured against trees in autumn colours in the the eastern German town of Kromlau November 4, 2014. (Photo by Hannibal Hanschke/Reuters)

Princess Diana relaxes on the sand during a visit to the beach on the Caribbean Island of Nevis January 4, 1993. (Photo by Mark Cardwell/Reuters)

A man with a cap on his face sleeps on a floor at the Mahabat Khan Mosque in Peshawar, Pakistan on March 4, 2019. (Photo by Fayaz Aziz/Reuters)

A woman poses for a photo at Hitchin Lavender farm in Ickleford, Britain, August 4, 2020. (Photo by Peter Cziborra/Reuters)

A woman and her son hold firecrackers during Diwali, the Hindu festival of lights, in Mumbai, India, November 4, 2021. (Photo by Francis Mascarenhas/Reuters)

“The scientists behind NASA's $2.5 billion Curiosity rover mission on Mars on Tuesday explained the nature of a tiny, gleaming "flower" embedded in Red Planet rock, and revealed where they'll be using the SUV-sized robot's drill for the first time”. – Alan Boyle via NBCNews.com

Photo: Scientists say that a “Martian flower”, seen here in an image from the Curiosity rover's Mars Hand Lens Imager, is a 2-millimeter-wide grain or pebble that's embedded in the surrounding rock. Another, darker-colored mineral grain can be seen above and to the left. (Photo by NASA)