How Much Bigger is a Super Moon?

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I haven’t had the chance to take my telescope out for a while, but the moon has been really beautiful the last few days. I got to thinking that over the last year or two I’ve taken a lot of pictures of the moon all using the same method. If I look back and check the dates of those images I may be able to see the difference between a ‘supermoon’ and a ‘micromoon’.

You’ve probably seen the term ‘super moon’ online a lot recently, it’s a popular click-bait headline word that blog posts like to throw around. Like all orbiting objects the moon orbits in a slight ellipse, not a perfect circle. A super moon is a full moon that occurs when the moon is closer to the Earth, also known as perigee. A micro moon is a full moon that occurs when the moon is furthest from the Earth, also known as apogee.

The moon’s average distance from the Earth is 239,000 miles, but has a perigee of 225,700 miles and an apogee of 251,900 miles.

I made a list of all the moon pictures I had taken in 2019 and compared it to a list of perigee and apogee dates. It turns out that I had a full moon image from January 20th (the night of the Lunar eclipse), which was only one day away from the January 21st perigee. I also had an image from November 8th, and though it wasn’t a full moon it was enough to make the image I was thinking of. November 8th was only one day away from the November 7th apogee.

Thankfully I already have the moon images I want! One day off for each is definitely close enough for my purposes. So how much bigger is a super moon?

combination_01 annotated.jpg

Both images were taken with my 10” telescope, a 2x barlow lens, and my Fuji XA2 mirrorless camera. Each image is a photo-stitch of multiple images. Camera settings were ISO 400 and shutter speed 1/140s. Raw images were combined into the side by side comparison in GIMP and then levels were adjusted in darktable.

I’m actually pretty surprised that the difference is so large, I was expecting a more subtle difference. Obviously this size difference isn’t shocking to the naked eye, but it’s definitely real!