The Moon is full tonight,
actually an hour before the end of the Universal Time day, 11 PM in Britain, 6 PM or earlier in American time zones.
This is one of the full Moons most distant from Earth – near apogee – as shown in the Moon-distance graph in Astronomical Calendar 2023.
But we don’t notice the differing apparent size of the Moon due to distance. What is significant is that the Moon’s orbit is “squeezed” – more elliptical – so that the following new Moon, Jann. 21, will be near perigee and a bringer of high tides.
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Of course the study would need to be a double-blind randomized controlled trial and need to be free of the corrupting influence of corporate greed to get unbiased results LOL. According to wikipedia, the size of the Moon at perigee is 33.48′ and at apogee is 29.40′, which is a ratio of 1.139, so it’s nearly 14% larger in terms of diameter. But in terms of area, the ratio of the area of the Moon at perigee versus apogee is 1.2968, so 29.7% larger with respect to area. I wonder which metric is the one we sense when looking at the Moon?
Diameter, I think. You can eyeball the width of a thing you see, sort-of-measure it, area is subtler.
So, we should be able to perceive that the moon looks 14 percent wider. Trouble is, we are comparing it to something we saw about 14 days ago (half of the “anomalisttic month”, the period from perigee to perigee). Or to a moon we saw fewer days ago, in which case the difference would be smaller.
I was out walking tonight under beautifully clear skies: Jupiter in the west, Mars above, and the full Moon high in the east. Unfortunately, I had read your blog entry earlier today so I knew the Moon was near apogee, which made me wonder if my impression that the Moon looked exceptionally small was genuine, or the result of foreknowledge LOL.
It’s subjective, isn’t it? Only way to determine whether “we don’t notice the differing apparent size of the Moon due to distance” would be for someone to make a study, asking lots of subjects.