Nikolay Korchekov / Reuters

Spectators watch a fireworks display presented to celebrate the 50th anniversary of Yuri Gagarin's historic spaceflight, in Moscow's Victory Park on April 12.

More than 500 parties are going on to celebrate the 50th anniversary of the first human spaceflight and the 30th anniversary of the shuttle program. Among the highlights: the debut of the trippy space documentary “First Orbit,” greetings from the International Space Station and the Mars500 simulation of a Red Planet mission, contests, giveaways — and the Google doodle of the day.

All these events tie into Yuri's Night, a global celebration of spaceflight that originated in Los Angeles 10 years ago. The annual event commemorates Soviet cosmonaut Yuri Gagarin's blastoff on April 12, 1961, plus Columbia's first-ever space shuttle flight on April 12, 1981. Today's anniversary is bittersweet because this may be the last year of the shuttle fleet's service.

Tonight's L.A. party is a star-studded affair at the Griffith Observatory, during which Yuri's Night co-founders Loretta Hidalgo-Whitesides and George Whitesides (who is now Virgin Galactic's president) will reflect on the past and look forward to the future. They're not the only ones. This year the parties are proceeding on all seven continents.

Google

The logo on the Google homepage was set up to launch Yuri Gagarin's rocket when moused over.

"Everyone from Google to the Los Angeles Times is making note of this historical landmark, and I'm thrilled to see how excited people around the world are to celebrate the spirit of exploration and discovery that Yuri Gagarin embodied," Yuri's Night assistant director Brice Russ said in today's overview. "Whether your nearest Yuri's Night event is down the street or 100 miles away, there's something you can do to participate."

To find out about that something, check the event list at the Yuri's Night website. Some events take place after April 12, so if you have to stay in tonight, there's still a chance that you can party down.

Also, there's still a couple of days before the deadline for the Yuri's Night video and print ad contests, as well as a space-tour sweepstakes. You could win an expenses-paid trip to Russia for a zero-G flight, or even to Baikonur to watch a Soyuz liftoff.

A whole constellation's worth of websites are celebrating spaceflight today, including Scientific American, Wired, Smithsonian Air & Space and of course our partners at Space.com.

Over at Spacevidcast, meanwhile, you could watch a global Yuri's Night webcast and snag one of a million e-book copies of Andrew Kessler's "Martian Summer." Yuri's Night has also teamed up with Posterous to set up a "Yuri's Night Live" sharing site for photos and videos. Don't forget to check in with Yuri's Night via Twitter, Facebook, Flickr and YouTube.

And speaking of YouTube, here's a selection of videos to get you in the holiday mood:

More about Yuri Gagarin and space history:

• Why the world remembers its first spaceman
• Fifty years later, relive the first space odyssey
• The sky's the limit for outer-space records
• Look for Yuri Gagarin on msnbc.com

Join the Cosmic Log community by clicking the "like" button on our Facebook page or by following msnbc.com science editor Alan Boyle as b0yle on Twitter. To learn more about my book on Pluto and the search for planets, check out the website for "The Case for Pluto."  

The whole world is gearing up for the 50th anniversary of humanity's first flight in space, made by Soviet cosmonaut Yuri Gagarin on April 12, 1961.

For Russians, the date is observed as Cosmonautics Day, an annual holiday going back to Soviet times. And for the past 10 years, the rest of the world has been celebrating the occasion as "Yuri's Night," which has replaced the Communist Party theme with a dance-party theme.

As of today, the Yuri's Night website has registered 321 parties in 61 countries, from Afghanistan to Vietnam. (And I still have hope for Zimbabwe.) The event's associate director and director of media relations, Brice Russ, emphasized that the event doesn't focus on Mother Russia or the Cold War.

"We call it Yuri's Night and celebrate Yuri Gagarin's flight, but it's not just a celebration of a single person doing a single thing," he told me. "It's celebrating what Yuri's flight stood for: exploration, adventure, scientific discovery. It's nice to see how far we've come in 50 years, and with Yuri's Night we'll be doing our best to go as far as we can in the next 50 years."

Russ pointed out that there's a strong U.S. angle to the April 12 festivities. "It's not just the 50th anniversary of Gagarin's flight, but it's also the 30th anniversary of the shuttle program," he said. 

10 years of Yuri's night
The first Yuri's Night festivities were organized in 2001 by two space enthusiasts named George Whitesides Jr. and Loretta Hidalgo. From the beginning, Whitesides and Hidalgo (who are now married) tailored the event for the next space generation rather than the Apollo era. Rock music, dancing, glamour and glitter are an accepted part of the Yuri's Night scene, but the pocket-protector crowd is welcome as well.

"It's pretty funny seeing space geeks mixing it up with the young and the beautiful," Hidalgo Whitesides said in a news release. "In Los Angeles, we see our share of space-inspired fashion. There are a lot of silver bikinis."

The highlights include:

• Two contests to get the space-exploration juices flowing. One calls for contestants to create a print ad (poster, magazine advertisement, postcard, etc.) that would inspire readeres to "think about space and support humanity's future among the stars." Grand prize is a four-day trip to Russia for a zero-gravity flight aboard an Ilyushin-76 airplane, valued at $9,000. The other contest offers $500 for the best Yuri's Night tribute video. Deadline for both contests is April 15.
• A sweepstakes that offers an expense-paid trip to Russia's Baikonur Cosmodrome in Kazakhstan, to see a Soyuz liftoff like the one that took place today. Value: $9,000. Entry deadline: April 15. Cost of entry: $0.
• The relaunch of the Yuri's Night app for the iPhone, which gives you the full rundown on hundreds of events, as well as a countdown clock so you don't miss the liftoff. (You can also follow @YurisNight on Twitter or check out the Yuri's Night Facebook page.)
• The world premiere of an experimental documentary film titled "First Orbit," produced by British filmmaker Christopher Riley with music by Philip Sheppard. The 105-minute film will be shown for the first time on YouTube on April 12, and at hundreds of Yuri's Night venues around the globe.

First night for 'First Orbit'
"First Orbit" deserves special notice: The movie re-creates 1961's one-orbit flight, using exclusive imagery from the International Space Station. Riley worked things out with the European Space Agency to have Italian astronaut Paolo Nespoli shoot footage from the station's Cupola observation deck as the station flew along the same orbital path that Gagarin followed 50 years earlier.

Riley told me that the station follows Gagarin's route every couple of days. "The tricky part was that I needed to film at exactly the same time of day that Gagarin flew," he said. That happens only every six weeks or so. Fortunately, Nespoli was able to get most of the imagery during an orbital pass in early January.

The soundtrack blends the original audio from Gagarin's mission with Sheppard's score, plus reports about the flight that aired on Radio Moscow, TASS and the BBC 50 years ago.

Riley said the "First Orbit" project served as a "sort of overture" for a film he's planning to make about the decades-long international drive to explore outer space. "I'd really like to do a film in 30 languages, where everybody talks about their own experience in Earth orbit," he told me.

So what will happen to "First Orbit" when Yuri's Night is over? "It's a bit like a dead lottery ticket," Riley joked. "I suspect no one's going to be interested in the film for a few months after April 12. But I think this film will be like a good Christmas movie. It'll come back every year, around April 12."

What will you be doing for Yuri's Night? Do you remember what it was like 50 years ago, when Gagarin flew? Or 30 years ago, when a space shuttle blasted off for the first time? Or even 10 years ago, when Yuri's Night got its start? Take this opportunity to share your spaceflight memories in a comment below.

More about space history:

• Why the world remembers its first spaceman
• Where were you when Apollo flew?
• Audio slideshow: Voyage of the millennium
• Timeline: Glory days on the final frontier
• Timeline: Trace the space shuttle era