10.

Apollo 11 astronaut Buzz Aldrin stands on the moon on July 20, 1969. The plexiglass of his helmet reflects astronaut Neil Armstrong, taking his picture.

Walking on the Moon's surface a quarter million miles away from Earth presented a new set of problems to spacesuit designers. Not only did the moon explorers' spacesuits have to offer protection from jagged rocks, but the suits also had to be flexible enough to permit stooping and bending.

The suits had to provide protection from bombardment by micrometeoroids, tiny particles that constantly pelt the lunar surface from deep space, but also insulate the wearer from the temperature extremes of space.

Without the Earth's atmosphere to filter the sunlight, the side of a suit facing the Sun may be heated to a temperature as high as 250 degrees Fahrenheit; the other side, exposed to darkness of deep space, may get as cold as -250 degrees Fahrenheit.

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From Mercury to Starliner: The Evolution of the Spacesuit - NBCNews.com