47 years ago today, Apollo 11 landed on the moon

Buzz Aldrin on the moon, carrying two scientific instruments. (NASA)

Wednesday marks the 47th anniversary of when NASA astronauts first landed on the moon, a giant leap of an accomplishment that still resonates today, over four and a half decades later.

Astronauts Neil Armstrong, Buzz Aldrin, and Michael Collins blasted off from Earth on a massive Saturn V rocket on July 16, 1969. Four days later, the Eagle module landed on the surface with Aldrin and Armstrong inside; Collins stayed behind in the orbiting Columbia craft.

Millions of people back on Earth watched, captivated, as Armstrong was the first down the ladder, then uttered his now-famous line: “That’s one small step for man, one giant leap for mankind.”

Armstrong described the moon’s surface as being “very, very fine-grained as you get close to it— it’s almost like a powder.”

The astronauts eventually returned to Earth, splashing down four days later in the Pacific. On the moon, an American flag and a plaque that read, in part, “We came in peace for all mankind,” remained.

Wednesday, 47 years later, Aldrin took to Twitter, posting a short clip of the lunar lander’s descent, followed by Armstrong saying “the Eagle has landed,” as well as a GIF of the ship in orbit around the moon.

Aldrin, wearing a pair of red, white and blue suspenders, and a black T-shirt with an astronaut and an eagle on it, also appeared in a Facebook Live event commemorating the anniversary Wednesday.

Only 12 people have ever walked on the moon.

NASA also celebrated another important milestone on Wednesday: the 40th anniversary of the Viking 1 lander's arrival on the surface of Mars. Viking 1 and 2 were launched from Earth in 1975, and on July 20, 1976, Viking 1 landed on the red planet-- the first time an American craft had done so. (Its originally scheduled landing date was July 4, 1976.) Viking 1 beamed back pictures, analyzed the planet, and even kept transmitting information until November, 1982.

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