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Some say the Earth isn't just a rock we live on; it's actually humanity's spaceship. For this Earth Day, a handful of astronauts aboard the International Space Station filmed an Imax movie to spread the message that we all need to perform some maintenance to keep our ship's life support working properly.

CNET spoke about the film to NASA astronaut Kjell Lindgren, who returned in December from half a year on the space station. In the film, called "A Beautiful Planet," Lindgren is seen playing his bagpipes in orbit and eating space lettuce. He and a handful of other astronauts also shot much of the footage themselves from the space station after learning how to operate Imax cameras.

"It was like a mini film school and we were able to learn from one of the masters," Lindgren said of director Toni Myers, who directed the Imax film "Hubble 3D." "I took it on as something of a personal project."

In addition to showcasing the unique vantage point the space station has in observing Earth's beauty, the film deals with how planet is changing or, more accurately, the way it is being changed.

"You can see the effects of humanity on the planet, from agriculture, from pollution. It can be impossible to see some cities below" the smog, Lindgren told me from NASA in Houston. "You can also see that even though we are having an effect, there are actions that can be taken to change a lot of that."

Lindgren recalled how one major Chinese city shut down traffic to clear up the weather for the weekend and that the smog dissipated, making the once-hidden metropolis viewable again from orbit. He said his time aboard the space station helped reinforce the idea that people are capable of great things when working toward a common goal.

"If we can build a space station while living in it -- that's kind of like building a 747 while it flying it around the Earth -- then we can look at the Earth and limit these changes and keep our spaceship healthy," he said.

"A Beautiful Planet" premieres April 29.