Author Topic: Lunar Eclipse 28 September  (Read 1008 times)

charles

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Lunar Eclipse 28 September
« on: September 28, 2015, 03:07:32 PM »
The weather in bath was perfect for this morning's lunar eclipse. I woke up in time to see the earth's main shadow (the umbra) half way across the moon at 2.30 or so, when the contrast between even the penumbral moon (partially in shadow)  and the umbra was very great; almost like seeing a partial phase moon. As the full umbra encroached the sky darkened noticeably. At totality (after 3.10) the moon was then a beautiful  orangey rosy colour. 15x70 binoculars seemed to give the best view. They also showed a pleasing and familiar pattern of not very bright stars in that part of Pisces which would have been completely washed out by an uneclipsed moon. Elsewhere the sky was dark enough for any kind of observing; one of my tests, M33, not so far from the Moon, was an easy pick up.

I wondered afterwards what magnitude the moon had at full eclipse. A full moon is about -12. My starting point was Venus at it brightest (-4.4), but the comparison (by memory) is difficult because Venus is for the naked eye a point source. But overall I would say the moon was not much brighter. -6 perhaps? That would make it x250 fainter than a normal full moon.

There was quite a lot of media publicity in advance for the eclipse, but unfortunately much of it banged on about this being a "supermoon" eclipse, as if this was something significant. The moon's orbit is not quite circular, and its distance from the earth varies about 6% either side of the mean, and therefore so, too, does its apparent size. This one happened to be more or less when the moon was at its closest, and therefore biggest. This makes no practical difference for observing the moon whether in eclipse or not, and the media (and some pundits who should know better) only confuse people by pretending it does. Eclipses of the sun, where the moon's distance matters a great deal, are another matter entirely. >:(
End of rant :)