Amazingly enough, we've been there.

The moon is the only extraterrestrial world to have been visited in person by human explorers. And, even more astounding, we did it with slide rules and vacuum tubes! (Ask your grandparents.)

Of course, it made sense to go there first. At an average distance of 384,000 kilometers (239,00 miles), the moon is so near that no other known object in the sky can come close to showing the amount of detail visible to the earthbound stargazer.

The moon is also quite large relative to Earth. It's fully 27% of Earth's diameter, but only 1.2% of its mass. Not quite a double planet (as Pluto and its moon Charon are sometimes described) but it's close!

The moon is Earth's dancing partner in space as both waltz around the sun.