Now the European Space Agency released an epic time-lapse video of his work.
Gerst was a geophysicist in Germany before the ESA picked him to become an astronaut in 2009.
His background made him well-suited for this year's "Blue Dot" mission on the International Space Station.
According to the ESA, the mission is a six-month scientific program designed to "improve life on Earth or prepare for further human exploration of our solar system."
During the mission, which lasted from May to November, Gerst worked on experiments in physical science, biology, human physiology and radiation, and he was also responsible for docking spacecraft, unloading cargo and other general space-station chores — including a spacewalk.
Although he was busy, Gerst managed to set up a camera to automatically take photos of Earth.
Now the ESA used 12,500 of those photos to produce the ultra-HD time-lapse video.
The six-minute clip may seem long by Internet standards, but it squeezes a lot of Earthly delights into 360 seconds. Source