APOD: An Almost Eclipse of the Moon (2020 Jan 18)

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APOD: An Almost Eclipse of the Moon (2020 Jan 18)

Post by APOD Robot » Sat Jan 18, 2020 5:06 am

Image An Almost Eclipse of the Moon

Explanation: This composited series of images follows the Moon on January 10, the first Full Moon of 2020, in Hungarian skies. The lunar disk is in mid-eclipse at the center of the sequence though. It looks only slightly darker there as it passes through the light outer shadow or penumbra of planet Earth. In fact during this penumbral lunar eclipse the Moon almost crossed into the northern edge of Earth's dark central shadow or umbra. Subtle and hard to see, this penumbral lunar eclipse was the first of four lunar eclipses in 2020, all of which will be penumbral lunar eclipses.

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Ann
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Re: APOD: An Almost Eclipse of the Moon (2020 Jan 18)

Post by Ann » Sat Jan 18, 2020 10:29 am

György Soponyai posted a composite image of three lovely lunar eclipses in the Recent Submissions forum recently.

viewtopic.php?p=298686#p298686

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Re: APOD: An Almost Eclipse of the Moon (2020 Jan 18)

Post by BDanielMayfield » Sat Jan 18, 2020 10:44 am

Ann wrote:
Sat Jan 18, 2020 10:29 am
György Soponyai posted a composite image of three lovely lunar eclipses in the Recent Submissions forum recently.

viewtopic.php?p=298686#p298686

Ann
Thanks for sharing that Ann. Outstanding work!
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Re: APOD: An Almost Eclipse of the Moon (2020 Jan 18)

Post by dhkaiser » Sat Jan 18, 2020 12:25 pm

No mention of the size differences in the images?

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Re: APOD: An Almost Eclipse of the Moon (2020 Jan 18)

Post by orin stepanek » Sat Jan 18, 2020 1:34 pm

Penumbra; Like close in horseshoe! :rocketship: :mrgreen:
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Re: APOD: An Almost Eclipse of the Moon (2020 Jan 18)

Post by Dan » Sat Jan 18, 2020 1:53 pm

Noticed that as well, but all the same size... I measured.
dhkaiser wrote:
Sat Jan 18, 2020 12:25 pm
No mention of the size differences in the images?

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Re: APOD: An Almost Eclipse of the Moon (2020 Jan 18)

Post by Chris Peterson » Sat Jan 18, 2020 2:50 pm

dhkaiser wrote:
Sat Jan 18, 2020 12:25 pm
No mention of the size differences in the images?
APOD-Soponyai-PenumbralEclipse_size.jpg
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Re: APOD: An Almost Eclipse of the Moon (2020 Jan 18)

Post by shaileshs » Sat Jan 18, 2020 3:08 pm

Chris Peterson wrote:
Sat Jan 18, 2020 2:50 pm
dhkaiser wrote:
Sat Jan 18, 2020 12:25 pm
No mention of the size differences in the images?
APOD-Soponyai-PenumbralEclipse_size.jpg
And we are supposed to believe the green lines drawn along the edges are really perfectly parallel ? Not just drawn at the edges and tapering slightly ? ;-) Ha ha ha.. Just kidding! I know it's just a visual perception/confusion. I was about to post funny comment "I didn't know eclipses make the moon smaller ;-)" and I saw this being mentioned already..

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Ictinus and Callicrates

Post by neufer » Sat Jan 18, 2020 4:00 pm

shaileshs wrote:
Sat Jan 18, 2020 3:08 pm
Chris Peterson wrote:
Sat Jan 18, 2020 2:50 pm
dhkaiser wrote:
Sat Jan 18, 2020 12:25 pm

No mention of the size differences in the images?

And we are supposed to believe the green lines drawn along the edges are really perfectly parallel ? Not just drawn at the edges and tapering slightly ? ;-) Ha ha ha.. Just kidding! I know it's just a visual perception/confusion. I was about to post funny comment "I didn't know eclipses make the moon smaller ;-)" and I saw this being mentioned already..
http://www.greece-is.com/the-optical-illusions-that-make-the-parthenon-perfect/ wrote:

The Optical Illusions That Make the Parthenon Perfect
John Leonard | January 12th, 2018

<<As viewers, we welcome and accept the Parthenon’s outward beauty and seeming perfection, but we don’t often stop to ask ourselves why the building so affects us. The answer is that the Parthenon’s architects, Ictinus and Callicrates, and its chief sculptural artist, Phidias, have incorporated numerous “hidden” devices within its marble construction and carved decorations that were designed to trick the viewers’ eye, to make us believe we are witnessing something perfectly regular, sensible and balanced in all its aspects.

Looks certainly can be deceiving! Who would believe that, in fact, there are virtually no straight lines or right angles in the Parthenon? This enormous temple appears at first glance to be a giant rectilinear construction, all of whose lines are straight! And does it seem sensible to the rational mind that the base of the temple – its stepped pedestal or stylobate – is actually domed, not flat?

The four corners of the pedestal droop gracefully downward, such that if one were to stand on the top step and look lengthwise along the building at someone else also standing on the same step at the opposite end, these two observers would only see each other from about the knees up. This doming of the temple base was reputedly done to avoid an optical “sagging” of the building’s middle that would have been perceived along its east and west ends and especially along its long north and south sides, if its lines were actually designed and built to be perfectly straight.

Additional refinements in the Parthenon include the slight inward leaning of all the columns in the Doric colonnade surrounding the building. The corner columns are slightly larger in diameter than the others and lean inward in two directions; that is, diagonally to the corner. They also are set in such a way that there exists a smaller space, or intercolumniation, between them and the next column.

Meanwhile, the columns themselves are not straight along their vertical axes, but swell in their middles. This phenomenon, called “entasis,” intended to counteract another optical effect in which columns with straight sides appear to the eye to be slenderer in their middles and to have a waist. Furthermore, the whole superstructure of the outer facades of the temple, above the level of the columns (the “entablature”), also curves downward at the corners, to mirror the stylobate and carry upward the temple’s overall domed curvature.>>
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Re: APOD: An Almost Eclipse of the Moon (2020 Jan 18)

Post by Boomer12k » Sat Jan 18, 2020 8:52 pm

A dime... grazing past the shadow of a silver dollar....

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