The Same Moon

We recently recorded this question.

Melissa: Hi, my name is Melissa and I’m from Chicago, Illinois, and my question is: if I’m living in California and I’m talking to a friend in New York City, and we look at the moon at the same time, does it look the same to both of us? If I’m in the United States and I’m looking up at the moon and I have a friend that’s looking up at the moon in Australia, does the moon look the same?

The short answer is yes. On any given day, we all see the same moon in the same phase — all across the globe.

But we don’t see the moon at the same time — just as we don’t see the sun at the same time. Earth’s spin on its axis swings you around to where the moon is in space — just as it brings the sun into view at sunrise. The moon rises later in California than in New York, just as the sun does — and it rises much later, half a day later, in Australia.

So just after moonrise in California, your moon might look big, orange and near the horizon — while your friend in New York might see it as whiter and higher in the sky. Those are local, sometimes atmospheric effects. Meanwhile, the moon might not be up yet in Australia. And while it’s true we all see the moon’s phase as basically the same — all the while its phase is shifting, ever so slightly, as the moon moves in orbit around Earth.

What you have in your mind?