(WGN-AM)- It was 40 years ago Monday, Apollo 11 touched down on the moon, and American astronauts Neil Armstrong and Buzz Aldrin became the first people ever to walk on its surface. Millions of people from across the world watched the amazing feat unfold on live television. Upon setting foot on the moon, Armstrong said something that will forever be etched in people's minds and in history books: "That's one small step for man. One giant leap for mankind."

The Adler Planetarium in Chicago is marking the amazing accomplishment.

As long as the weather's good, the Museum will stay open late tonight so people can check-out space through a telescope. People will be allowed to touch a rock that came from the moon, they'll be allowed to create their own "moon footprint," and, there'll be free cake at 3:17pm. That's the exact time Apollo 11 landed on the moon.

(WGN-TV contributed to this story)

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