Astronomy - Embracing the “Supermoon,” Hyped or Not

Much has been said and written about the Moon's proximity to Earth today. Is that a good thing or a bad thing?

About an hour ago I headed for the studios of WBUR, a terrific public-radio station in Boston, for a live interview on its syndicated "Here and Now" program. H&N's award-winning cohosts, Robin Young and Jeremy Hobson, are both really into what goes on in the skies above, and we often chat about celestial matters arising.

S&T Senior Editor Kelly Beatty, at left, chats about the November 14th "supermoon" with Here and Now cohosts Jeremy Hobson and Robin Young at the WBUR studios in Boston.
WBUR

Yet it was with mixed emotions that I agreed to be on the show. On one hand, we here at Sky & Telescope really don't think today's so-called "supermoon" is that big a deal. Yes, the Moon is closer today than at any time since 1948. And, yes, it's about 8% bigger across and thus 16% bigger in area and brighter than average. And, yes, it's occurring during a full Moon.

In their respective blogs for S&T.com, veteran observersBob King and Daniel Fischer offered some interesting ideas about perceiving the Moon's swollen orb. Fischer, in particular, believes the larger size can be noticeable.

Yet last night, which was wonderfully clear and even a little balmy by November standards, I looked at the Moon for a long time, intently — knowing that all those geometric rarities were occurring — and I couldn't convince myself that the Moon indeed looked bigger than usual.

Top: Here's how the not-quite-full Moon looked as it rose last night over Rick Fienberg's observatory in southern New Hampshire. Bottom: And here is Rick's image morphed to show the kind of swollen orb many people think they're going to see during a "supermoon."
Richard Tresch Fienberg

Am I an inexperienced observer? Hardly. Is my eyesight that bad? Hmm.  I asked around the S&T office. Most of my colleagues didn't think the enlargement was obvious, though one or two did. There was some consensus that the Moon looked brighter than usual, if not necessarily bigger. Here's Web Editor Monica Young's take:

"If I hadn't known last night's full Moon was 'super,' I probably wouldn't have noticed any difference when gazing up in a beautifully clear sky last night. I wasn't looking alone, though — and I have media hype to thank for that. The headlines inspired an impromptu star party at my house with a pair of five-year-olds who couldn't have been more excited to look at the Moon through my telescope. They noticed that the Moon was bumpy instead of smooth and that it was covered in circles. (That was before they began running in circles themselves.) Even the two-year-old was clamoring for a look."

And that's the crux of it. We all agree that the term "supermoon" creates artificially high expectations as to what an everyday person is going to see. On the other hand, it's undeniably a plus that lots of folks who wouldn't otherwise give the Moon a second look (or even a first one, for that matter) are heading outdoors to gaze upon the closest full Moon that many of them will likely see in their lifetimes.

. . . though probably not the brightest, due to something called the opposition surge. Right now the Moon is about 5½° south of the ecliptic, so each and every crater shows us a tiny bit of shadow. Were the full Moon right on the ecliptic — as it is just before and after a total lunar eclipse — there'd be no shadows at all and the opposition surge would cause the disk's brightness to jump upward of 20%. (I wish I had measurements to compare the brightness of last night's Moon with the extra-close one that coincided with September 2015's total lunar eclipse.)

But I digress. What do you think about this supermoon stuff? Can you see a difference? Do you care? Drop a comment below to let us know your thoughts.