Today — April 12 — marks the anniversaries of two significant milestones in mankind's foray into space.

Forty-five years ago (1961) Russian cosmonaut Yuri Gagarin become the first human being to escape Earth's gravity and enter space. Gagarin made the 108-minute flight in the Vostok 1 spacecraft, achieving one orbit around Earth at a maximum altitude of 187.75 miles (302 kilometers) at a speed of 18,000 miles (27,400 kilometers) per hour.

Twenty-five years ago (1981) a new era in the space program began as NASA's first space shuttle, the Columbia, was launched in the morning skies above Cape Canaveral, Florida. The maiden mission, flown by veteran Apollo and Gemini astronaut John Young and first-time spacefarer Robert Crippen, spent more than 54 hours in Earth orbit putting Columbia through its paces before landing at Edwards Air Force Base in California.

A number of events are planned around the globe to commemorate this date. In 86 cities on all seven continents (including Antarctica), a worldwide party called "Yuri's Night" is scheduled at universities, observatories, museums, community centers, pubs and other venues. In the U.S., events are planned in Atlanta, Austin, Boston, Boulder, Cape Canaveral, Houston, Las Vegas, Los Angeles, Minneapolis, Oklahoma City, Orlando, Philadelphia, San Francisco, Seattle, Washington DC and numerous other towns. For more information, visit www.YurisNight.net.

NASA's Web site is celebrating the inaugural Columbia voyage, STS-1, as "the Boldest Test Flight in History." Visit www.nasa.gov for complete coverage, including a video retrospective, a podcast interview with Crippen, and other features.

Also, Young and Crippen were to mark the anniversary of their flight at an event this morning at the Johnson Space Center in Houston, appearing with Senator Kay Bailey Hutchison of Texas, according to Space.com.

"To fly on the first one was a test pilot's dream," Crippen told Space.com about his spaceflight debut. "It was an exciting ride."

However, remembrances of that maiden voyage are marred by the knowledge that the Columbia was lost in 2003 when it burned up on re-entry with seven astronauts aboard.

Star Trek: Enterprise honored the lost shuttle by naming the NX-02 starship after it. Conversely, the first space shuttle — which was used as a test vehicle and never launched into space — was named Enterprise as a result of a letter-writing campaign from Star Trek fans.

Gagarin, who has a crater on the Moon named after him, died in 1968 in the crash of a plane he was test-piloting. The planet Gagarin IV in "Unnatural Selection" (Star Trek: The Next Generation) also was named after him.

More information about this story can be found at the links below.