On Sunday, July 20, NASA marked a major milestone. Forty-five years ago, Sunday, people flocked to their televisions to witness Neil Armstrong and Buzz Aldrin landing on the moon.

That evening the astronauts opened the hatch to the Apollo 11 lunar module and stepped onto the moon's surface with Armstrong's immortal words, "one small step for a man, one giant leap for mankind."

image credit: NASA

image credit: NASA