Another Hyped-up Full Moon

Here we go again — more of this “Supermoon” hype.  Here’s the unhyped reality.

A nice full moon. Probably not super.

This month’s full moon happens to occur when the moon is near perigee — its closest approach to Earth.  You’ll see all kinds of statistics:  “X% bigger! Y% brighter!” Of course, they rarely specify the reference point for the statistics. I’d guess the articles compare this full moon to a full moon near apogee (the farthest distance from Earth). That way, you get bigger numbers to toss around.

For the record: a full moon at perigee appears to be about 16% bigger and 30% brighter than a full moon at apogee.

So, will you see much of difference between the May full moon and any other full moon? It’s not likely.

The difference in size  won’t be easy to see without properly scaled side-by-side photos. The full moon illusion wouldn’t help either.

The difference in brightness sounds impressive, but our eyes gauge brightness on a logarithmic curve. It takes almost a doubling in brightness for the difference to be obvious.

In short, there won’t be much of a visual difference.  This sort of hype annoys me because it sets people up to be disappointed. That sours people on what could be a rewarding hobby.

Find someone you like spending time with. Then go out and enjoy a lovely full moon on a nice spring evening.


About Tim Cole

Astronomy enthusiast and educator, all-around fancier of dark skies and starry nights
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