NASA followed one of the classic rules for Internet videos during its first space-to-Earth Google Hangout on Friday: If you want to bring in the viewers, don't forget the cats.

Astronaut Tom Marshburn's demonstration of how an astronaut in the International Space Station's zero-gravity environment can imitate a falling kitty was one of the highlights of the hourlong video chat, which addressed more than 30 questions sent in via YouTube, Twitter, Facebook, Google+ and real-time hookups with kids across the country.

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One of the questions, phrased in the form of a video, came from the host of the "Smarter Every Day" webcast series, a rocket engineer known as Destin. (He keeps mum about his last name to protect his kids, who appear in the webcasts.) Destin ran his own mini-video showing how a falling cat rights itself in the air to land on its feet, and asked if the astronauts could match that feat in zero-G.

"We don't have any cats onboard," said space station commander Kevin Ford, "but we have a medical doctor who maybe can try to demonstrate the next best thing to a cat."

Marshburn, who's a physician as well as an astronaut, then proceeded to float in front of the camera and twist his body to change position — not quite as adroitly as the cats, but not bad for a human.

"I hope you believe that what you saw happened with the cat isn't a mystery, and that it can happen in space, too," Ford concluded. You can watch the demonstration around the 33-minute mark in the Hangout video.

Other astronauts participating in the chat included Canada's Chris Hadfield aboard the station, and NASA's Ron Garan and Nicole Stott on the ground. They took questions passed along from social media by NASA moderator John Yembrick; from live-video hookups with classrooms at University High School in Orlando, Fla., and Mescalero Apache School in New Mexico; and from a youngster named Fred whose video link was facilitated by the Make-a-Wish Foundation.

Here are a few more nuggets from the video:

• Hadfield said that this week's communications outage on the space station was "not that big a deal," and that the crew members were well-trained to operate the station even when they were out of contact with ground controllers. "It wasn't any sort of panic or anything, it was just us dealing with a problem on the ground, and our crew dealing with the problem on board," he said. 
• Getting into the right sleep cycle is a big challenge on the space station, where there are 16 sunsets and sunrises every day. Garan said that when it gets close to bedtime, some astronauts avoid looking out the window at Earth's bright side. Stott said NASA is experimenting with a scheme that makes the lighting inside the space station more bluish for the "morning" of the astronauts' workday, and more orangish during the "evening."
• The station's crew members showed off the medical kits they kept on board for health problems, but if there's a life-threatening emergency on board, astronauts would get into one of the Russian Soyuz capsules attached to the station and fly the stricken crew member back to Earth. "Our Soyuz is our ambulance," Marshburn said. 
• When the astronauts were asked which scientist from the past they wish they could bring to the space station, Marshburn instantly said Isaac Newton, who drew up physics' three laws of motion in the 17th century. "We see what he could only imagine," Marshburn said. 
• Taking pictures from space is a challenging task that requires advance training, due to the sharp contrast between the blackness of outer space and the brilliance of the planet below, Hadfield said. But there's one big plus: Because of the zero-G environment, it's a lot easier to handle huge telephoto lenses. "Every photographer in the world would love to have that much glass in front of their eyes ... and not have to balance it," Hadfield said.
• When the astronauts were asked about their growing social-media stardom, Hadfield said, "I don't think anybody tries to push the edge of human experience more than we do." Being able to see the whole world below is "too good an experience not to share," and avenues such as Twitter, Facebook and Google+ help facilitate that, he said. He noted that a lot of the astronauts' popularity had to do with their unique perspective. "We know just how lucky we are to be here," Hadfield said.

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For more outer-space video goodness, tune in the Weekly Space Hangout at 3 p.m. ET Friday. Yours truly will be on the screen along with other scribes to review the week's space news, including the meteor blast that hit Russia a week ago.

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

Friday's live Google+ Hangout represents one small step for NASA, one giant leap for the Web-based videoconferencing tool.

Space-to-Earth hookups are nothing new for the International Space Station: NASA TV regularly broadcasts video from the orbital outpost as it circles the globe at an altitude of 240 miles (385 kilometers). Astronauts have been sending Twitter updates and Flickr photos from space for years. Heck, even NASA's robots have Facebook pages. But Friday's hourlong event, scheduled to run from 10:30 to 11:30 a.m. ET, marks the first time that NASA has done a Hangout.

"We're looking forward to it," said Jason Townsend, a spokesman at NASA Headquarters in Washington.

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He said NASA has selected 20 video questions from the scads that were sent in by the agency's social-media followers, and at least some of those questions will be aired for the space station astronauts to answer during a 20-minute downlink opportunity starting at 11 a.m. ET. "We're angling to fill every minute," Townsend told NBC News.

Three of the space station's six astronauts — station commander Kevin Ford, NASA colleague Tom Marshburn and Canada's Chris Hadfield — will participate in the space-plus-Earth Hangout. (The three others, all Russians, will presumably be minding the store.)

Townsend said that for the balance of the hour, questions will be handled by two NASA astronauts on the ground: Ron Garan, a social-media star who's in nearly 3 million Google+ circles; and Nicole Stott, who participated in the space station's first live NASA Tweetup in 2009.

Questions can be submitted during the Hangout via Google+, via Twitter (by including the hashtag #askAstro) and via NASA's Facebook page.

The outer-space Hangout is just the latest leap for NASA's social-media strategy: The Tweetups of the late space shuttle era have given way to a string of NASA Social gatherings. One took place just this week at NASA Headquarters. NASA regularly sets aside seats for social-media mavens at big events, including next month's SpaceX Dragon launch.

Last year, NASA's social-media teams presented 16 events that brought more than 1,000 followers to NASA facilities and other spacey locales. Mars Curiosity rover has been the star of the show, thanks in part to her (yes, her) 1.3 million Twitter followers. During the rover's landing last August, NASA served up a record 36 million webcast streams, and the six-wheeled robot has been known to check in to Foursquare from Mars.

How can the Three Amigos on the space station possibly compete with Curiosity (and her cantankerous, non-NASA-sponsored alter ego, Sarcastic Rover)? Tune in on Friday and find out.

More marvels from the space station:

• Astronaut's artistry hits warp speed
• Space-plus-Earth duet makes debut
• Online contest to boost space station power

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After NASA's Hangout, keep an eye out for the Weekly Space Hangout, which brings space scribes together for an hour starting at 3 p.m. ET. Universe Today's Fraser Cain and Astrosphere's Scott Lewis (the Bald Astronomer) are among the ringleaders.

Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.

Even the astronomers on the science team for NASA's Kepler planet-hunting mission are marveling at the new worlds they're finding.

There's certainly a lot to marvel at: Just this week, Kepler astronomers announced the discovery of not just one, but two binary-star systems that have at least one planet each, reviving visions of the double sunset on Luke Skywalker's home world in the "Star Wars" saga. Another group of scientists drew on data from Kepler to detect the three smallest exoplanets yet discovered, including one just about the size of Mars.

The revelations at the American Astronomical Society's winter meeting in Austin, Texas, demonstrated that the number and diversity of the planets being found beyond our own solar system is growing by leaps and bounds. An august group of space commentators, including yours truly, celebrated the diversity during today's Weekly Space Hangout. And astronomers were celebrating in Austin as well.

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"Any kind of system you can think of, if it doesn't violate the laws of nature, it probably exists somewhere out there," Virginia Trimble, an astronomer at the University of California at Irvine, told reporters. "So as long as people think up new techniques, they will also find new types of planets. There will surely be lots of new, neat stuff in the coming years."

In an email, Berkeley astronomer Geoffrey Marcy, who has been in on the planet quest for 20 years and is a member of the Kepler science team, went positively gushy over the latest findings ... but also pointed out that the quest has really just begun:

"The NASA Kepler space telescope has discovered well over 2,000 strong candidate planets around other stars.  No exoplanet survey is even close to this coverage and statistical integrity.

"For each of those exoplanets Kepler finds, we have detailed knowledge of the planet's orbital period and the planet's orbital distance from its host star. More impressively, we know the planet's size (diameter) quite accurately. For some of the planets, we have also measured their mass and density, with some planets found to be definitively solid.

"With this wealth of information about over 2,000 planets, we continue to study the occurrence of planets around other stars. This work gives us a census of planets in the Milky Way galaxy. The 2,000 exoplanets is still too few to give an accurate answer. A useful census of humans on Earth requires that well over 2,000 people be surveyed. So it is with planets in the Milky Way galaxy. A useful census requires that thousands be sampled, and with accuracy. We desire integrity in our surveys of planets and people.

"Three weeks ago, the Kepler team announced the first two Earth-size planets. Only Kepler has sensitivity to Earth-size planets. [Now we have announced] the first Mars-size planet around another star. ... These discoveries by Kepler will mark an historic moment in the history of science, approaching the trans-oceanic voyages of the 15th century and the first steps on the moon.   Kepler is indeed finding new worlds."

The Kepler mission identifies potential new worlds by looking for the telltale dips of starlight that occur when a planet passes over the disk of its parent sun. Other methods are used to confirm the mass of alien planets, including a method that checks for a characteristic gravitational wobble in stars that have planets. And yet another method, called microlensing, was used in another study released this week that estimated there could be 160 billion planets in the Milky Way. There's a chance that estimate will turn out to be too high. There's a better chance it'll turn out to be too low. But in either case, astronomers now recognize there could be tens of billions of new worlds out there.

Some of those worlds no doubt will have the conditions conducive to life as we know it. Studying such planets could help us one of the deepest questions we have about the universe: Are we alone?

But in order to do that, the quest has to continue. Right now, funding for the $600 million Kepler mission is due to run out in November, and discussions about an extension are under way. Theoretically, Kepler could gather enough data by November to detect Earth-size planets in Earth-scale orbits around sunlike stars, but an extension would provide scientists with more confidence about their existing candidates — and also give them the chance to cast a wider net.

Chances are the mission will be extended. "It would seem to me just nuts to have it out there and turn it off," one astronomer, Greg Laughlin of the University of California at Santa Cruz, told Space.com. But the success of Kepler (and its European counterpart, COROT) should get people talking about what to do for an encore. So brace yourself for an alphabet soup of exoplanet-mission acronyms ranging from EChO to MPF to PLATO to WFIRST.

Odds and ends from the week in space:

• Hey, kids! Want to keep up with the lengthening list of exoplanets? Check out Hanno Rein's free Exoplanet app for iPhone, iPad and iPod Touch. There are planet catalogs for other mobile platforms as well, such as Exoplanet Catalog for Android and the Astronomy app for Windows Phone. Got more apps? Add your recommendations in a comment below.
• Speaking of apps, Powellware's newly released Mars Images app is getting some good reviews. The app for iPhone/iPad/iPod Touch/Android delivers the latest images from NASA's Opportunity rover on Mars.
• Remember the big radio-telescope array that Jodie Foster was plugged into when she heard the alien transmissions in the movie "Contact"? The real-life telescope complex in New Mexico where those scenes were filmed has been known as the Very Large Array, but during the AAS meeting, the National Radio Astronomy Observatory announced that it'll be renamed the Karl G. Jansky Very Large Array to honor Karl Jansky, the founder of radio astronomy. The name was selected from among 23,331 suggestions submitted by 17,023 people from more than 65 countries, the NRAO said. The new moniker will no doubt be shortened to the Jansky VLA, or the Jansky Array.
• If you've got an hour to spare, watch the Weekly Space Hangout video above, in which I and other Web-based worthies hold forth on a variety of out-of-this-world topics. And if you've got another hour to spare, perhaps while you're exercising at the gym, listen to last week's "Virtually Speaking Science" podcast, featuring my chat with Ig Nobel impresario Marc Abrahams. And stay tuned for the Feb. 1 installment of "Virtually Speaking Science," when we'll be talking about science policy and politics.

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Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.