SEATTLE — Charles Simonyi may still be described as a space tourist even though the Microsoft billionaire has no plans to take a third vacation on the International Space Station and hasn't hung out in outer space for a few years.

He's still obsessed with space and is heavily involved in the Seattle Museum of Flight's new space gallery, which is named in the philanthropist's honor.

Since 2002, Simonyi has been running his own company called Intentional Software that specializes in creating industry-specific computer software, and he recently he took on a new title: book publisher.

The son of a Hungarian physicist, the 63-year-old just made one of his dad's dreams come true by helping translate the senior Simonyi's epic about physics into English.

"A Cultural History of Physics" by Karoly Simonyi, who died in 2001, is a heavy tome with an intimidating name but inside the non-scientist will find lots of pictures and stories that offer a whimsical side of physics.

Flip through the book, which has had five editions in Hungarian and three in German, and you'll find a full-page diagram showing how the scientists of the 17th century enjoyed dismissing each other's theories. A diagram and an explanation by Sir Isaac Newton of how rainbows are formed are on another page.

An illustration of a cat with its hair standing on end may catch your attention toward the end of the book. If you stop to find out why the cat is on the page, you'll find an explanation of quantum mechanics and radioactive decay.

Simonyi says that page is just one of many parts of the book that illustrate his father's sharp sense of humor.

1. Space news from NBCNews.com
   1. 

      KARE
      Teen's space mission fueled by social media

      Science editor Alan Boyle's blog: "Astronaut Abby" is at the controls of a social-media machine that is launching the 15-year-old from Minnesota to Kazakhstan this month for the liftoff of the International Space Station's next crew.

   2. Buzz Aldrin's vision for journey to Mars
   3. Giant black hole may be cooking up meals
   4. Watch a 'ring of fire' solar eclipse online

The project was personal for Simonyi but has elements of other things he does for work and fun: it was a challenge, it's about science and it has the potential to help people learn.

The man who led the Microsoft teams that developed Word and Excel also is great at explaining scientific concepts. From the stories he shares about his father, that's a quality he likely inherited from the former physics professor, who Simonyi says inspired generations of Hungarian electrical engineers.

(Msnbc.com is a joint venture of Microsoft and NBC Universal. Comcast holds a controlling interest in the latter.)

Charles Simonyi left Hungary at 17, and says his interest in space as a child helped him learn English — two of his first English words were "propellant" and "nozzle." His knowledge of space trivia led him to win a junior astronaut contest at age 13. The prize was a trip to Moscow to meet one of the first cosmonauts, Pavel Popovich.

His next project will be writing a book about his space trips in 2007 and 2009 with Virginia-based Space Adventures, which cost him a total of $60 million. The idea was inspired in part by all the questions he was asked on a website he set up during his space travels called "Charles in Space."

"I love talking about space flight," said Simonyi, who says the privilege of going to space can be measured by the fact that only about 500 people have ever left Earth's atmosphere. "If you've been there, then you kind of have this obligation to tell people about what it's like and share the experience."

Earlier this week, he dropped off a space toilet at the Museum of Flight.

Going to the bathroom in space is quite a bit more complicated than sleeping there, and Simonyi is enthusiastic about sharing all the personal, yet technical, details with anyone curious. He even made a video about the mechanics of bodily functions in zero gravity.

Sleeping is actually easier in space than on earth, Simonyi said.

"You can sleep anywhere in any position — vertical, horizontal or at an angle," he said, adding that he slept in a room where the Russian space suits were kept. "It was out of the way and pretty quiet. I enjoyed it very much."

Thanks to Simonyi, the museum also has one of the Russian Soyuz space capsules he used to ride back to earth from the space station. Simonyi gave $3 million to the museum to help build the space gallery, and has given the Soyuz capsule, a space suit, space toilet and other artifacts to the museum on a long-term loan.

Eventually the small cone-shaped capsule will sit beside the giant U.S. space shuttle trainer, for which the hangar-sized gallery was built.

Simonyi said he never felt claustrophobic on the space station or in the Russian ships to or from the station.

"I find the spacecraft very comfortable, very cozy," he said.

Nothing about the experience was scary, he said, even though he doesn't consider himself much of a daredevil. He is a pilot, flying both jets and helicopters.

He compared the experience of dropping back to earth in the Russian space capsule to snow skiing, from the s-turns the capsule makes as it falls through the atmosphere to the whooshing sound it makes as the air and heat blast off the surface.

Conversely, the idea of riding in a submarine miles beneath the surface of the ocean — like James Cameron did recently — that gives him the willies. "That takes guts," he said.