Google's homepage is sporting a doodle in honor of Yuri Gagarin, a Russian cosmonaut who became the first human in space 50 years ago today.

Google's homepage is sporting a doodle in honor of Yuri Gagarin, a Russian cosmonaut who 50 years ago today.

The image replaces the first "o" in Google with Gagarin in his space suit. When you first click on the image, Gagarin's Vostok 1 spacecraft takes off above the second "o" in the logo.

On April 12, 1961, 27-year-old Gagarin completed a 108-minute orbital flight in the Vostok 1, making him the first man in space. According to NASA, Gagarin did not actually operate the spacecraft's controls. In 1961, the effects of weightlessness had only been tested on dogs, so officials did not want to take any chances putting Gagarin in full control of the spacecraft. The mission was controlled by a ground crew, though there was an override key in case of emergency.

Upon his return, Gagarin was received as a national hero, but this status actually prevented Gagarin from making any future space flights. NASA says the Russian government wanted to protect its national treasure, so he was relegated to training MiGs. Ironically, Gagarin was was killed when his MiG-15 fighter plane crashed in 1968 during inclement weather. He was 34.

Earlier this month, from the Baikonur Cosmodrome in Kazakhstan, carrying Flight Engineer Ron Garan and Russian cosmonauts Alexander Samokutyaev and Andrey Borisenko to the International Space Station. Their spacecraft was nicknamed the Yuri Gagarin in honor of today's 50th anniversary.

Tuesday is also the 30th anniversary of the first U.S. space shuttle launch, the Columbia. NASA administrator Charles Bolden will host an anniversary celebration this afternoon, when where the agency's remaining space shuttles will spend their remaining days.

For more, see a of Gagarin's flight and career.

Google has made headlines for its recent doodles, meanwhile, including an in honor of author Jules Verne's 183rd birthday and that were live for two days in December.

Recently, it was revealed that for its popular homepage doodles, covering "systems and methods for enticing users to access a Web site."

For more on Google's doodles, see the slideshow below.