The Harvest Moon and Lunar Eclipse of September 17, 2024

On Tuesday night, at the designated time (9:35 PM), Trish talked me into going outside to observe the supermoon. I sighed, thinking about how comfortable I already was, but I grabbed my camera and out we went. Glad I did. A bonus was seeing a partial lunar eclipse at the same time. I got some nice photos.

What the heck is a supermoon, anyway? It's another word for harvest moon, which is a full moon when the moon is closer to Earth than usual. Technically, an astronomer would tell you this is when the moon is within 90% of perigee (which is the moon's closest approach to Earth in its orbit). Typically, the distance between Earth and the moon averages about 239,000 miles. On Tuesday night, it was at about 222,000 miles.

The traditional name harvest moon refers to the fact that it usually happens in the early fall, when many crops are almost ready for harvesting.

Okay, so what is a lunar eclipse? This is when the moon enters Earth's shadow. If you think about it, a lunar eclipse can only happen when the moon is full. Why? Because the moon is full only when Earth is directly between the sun and the moon. In other words, when you look up at the moon, the sun has to be directly behind your line of sight in order to fully illuminate the moon as you look at it. If the sun is not directly behind your line of sight, you see only a portion (a sliver) of the moon.

And on Tuesday, we were treated to a harvest moon AND a partial lunar eclipse at the same time. This is why it looks like there is a bite out of the top of the moon in my photo. That's Earth's shadow.