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55 Photos from Astronaut Scott Kelly's First Five Months in Space

Astronaut Scott Kelly and Russian Federal Space Agency cosmonaut Mikhail Kornieko are well into their year-long stay in space. The two just passed the five-month mark at the end of August.

The mission will focus on space's effects on the human body over the course of the year. From sleep studies to visual impairment, metabolic changes to crew relations, the data gathered from the expedition will be used to determine the risks and the room for improvement for future long-term missions, NASA reports.

There couldn't have been a better control for NASA's experiments than Kelly's identical twin brother, former NASA astronaut Mark Kelly. NASA plans to conduct a number of comparative studies on the two, as Mark Kelly remains on Earth.

(MORE: NASA Astronaut Scott Kelly Embarks on First-Ever Year-Long International Space Station Mission)

"It's not going to be easy to spend a year in that kind of isolated environment," Kelly, who left his girlfriend and two daughters, ages 20 and 11, on Earth for the duration of the mission, told USA Today. "But I think I'm up for the challenge."

Isolated as it may be, Kelly has been tweeting daily photos of his view from the International Space Station. View the slideshow above for photos of our planet from space from Kelly's first five months 200 miles above it.

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