Facebook Live — from Space! Astronauts Chat with Mark Zuckerberg

Three space station astronauts chatted live today (June 1) with Facebook's founder about experiments and fun in space, the things that training can't prepare you for, and the true astronaut ice cream.

The live-streamed video marked the first use of Facebook Live in space, and the discussion among Facebook founder Mark Zuckerberg, NASA astronauts Jeff Williams and Tim Kopra, and British astronaut Tim Peake garnered hundreds of thousands of views as it was happening and 2.6 million views as of press time.

Zuckerberg read off questions asked by Facebook users, throwing in a few of his own as well, delving into how the astronauts spend their time in space. [Amazing Space Photos by British Astronaut Tim Peake]

Besides running experiments that take advantage of the lack of gravity — "physical science experiments that range from combustion to fluid flow to microbiology," Kopra said — the astronauts discussed how their existence itself is an experiment to measure microgravity's effect on the human body. So they're constantly exercising and measuring the changes in their physical attributes, like eyesight.

All three astronauts trained to prepare for those effects and the tasks they'd have to complete on orbit. But some aspects of life in space were impossible to convey through training, said astronaut Tim Peake, who's nearly six months into his first space mission. (Peake is the first British astronaut to stay on the International Space Station.)

"As a rookie astronaut on my first flight, there were so many new experiences," Peake said. "The training is phenomenal, and we have a wonderful training team all around the world, in all our international sites. [But] it's the real experience of launching in a Soyuz rocket, seeing that first orbit of planet Earth going through a sunset, seeing a moonrise, seeing a sunrise — you can't put into words how beautiful a planet is from up here.

"And also having the privilege of seeing it change over the nearly six months that we've been up here now already, and seeing the Northern Hemisphere going from winter to summer, seeing thunderstorms at nighttime, the aurora — it's just absolutely incredible," he continued. "It's all of those kinds of elements that the training just can't prepare you for."

The trio also discussed communicating with the other astronauts, using English, Russian or a mix of the two; the internet service in space, which is relatively new and incredibly useful for keeping in touch, albeit much slower than on Earth; and the cool new virtual reality tech they've been testing out in the space station's halls.

The astronauts also delved into what they do for fun. Williams, who is on his third long-duration stay on the station, mentioned he also particularly enjoys viewing the Earth: "All the different seasons and stuff that goes by, the different lighting conditions and weather patterns, and all the geography and geology and the ocean currents, and thunderstorms, seeing lightning ripple across a weather system — that's a lot of fun," he said. "So we spend a lot of time in the window," he said.

Another pastime, often done during meals, is playing around in microgravity. "We all, from time to time, especially around the dinner table, play with our food in unique ways," Williams added. "We all get to be kids again."

The astronauts discussed how food tastes very slightly differentin microgravity, probably because an increase of fluid in the head makes the astronauts feel slightly "stuffed up." They particularly enjoy spicy foods for that reason, Williams said.

And Zuckerberg asked another food-based question, getting the information that really matters: Is astronaut ice cream a real thing?

"We know that the astronaut ice cream that you buy in the gift store, that powdery stuff — yeah, that's not real," Kopra said. "But we've had ice cream on board. When SpaceX came up, they delivered a bunch of ice cream and a freezer, so that's been quite the treat. I think we're down to our last few bars. We're trying to ration it."

The three astronauts won't have much longer to save it, though; Kopra and Peake return to Earth June 18, along with Russian cosmonaut Yuri Malenchenko, and Jeff Williams will head down in September with cosmonauts Alexey Ovchinin and Oleg Skripochka.

June 24, three new team members will join the orbiting lab: American astronaut Kate Rubins, Russian cosmonaut Anatoly Ivanishin and Japanese astronaut Takuya Onishi. But they probably shouldn't count on any leftover ice cream.

Email Sarah Lewin at slewin@space.com or follow her @SarahExplains. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.