thomas.st wrote: ↑
Thu Aug 09, 2018 12:24 pm
For this lunar eclipse there was an interesting APOD on 2018 July 30 showing the lunar eclipse from Rio. In the discussion of that APOD I wrote: Interesting to see the position of the moon and Mars as seen from Rio. Here from northern Germany looking at the southern horizont, Mars was found south from the moon and a little bit westwards (see for example picture in https://www.bbc.com/news/science-environment-44945452
, where Mars and the Moon are given as we saw it from here (assume lower picture Edge as the southern horizont)). Botafogo beach is (approx.) in north (west)-south (east) direction. In the July 30 APOD MarkBour then replied to this comment showing a picture showing the line of sight of the moon from Botafogo beach on a google map picture. Now in today's APOD you see that in such a southern latitude as Australia Mars is placed north of the eclipsed Moon. Whereas in Australia the eclipse was seen in the morning twilight, in Germany we saw it between (approx) 9:30pm to 12:00pm, in Rio they saw at sunset. So everything fits perfectly together. It would nice to have for today APOD a google map picture showing the Morning Peninsula and the line of sight of the Moon from the point the picture was taken.
Sorry to take so long to respond, I was away. But I do find this an interesting visualization problem. From your comment "everything fits perfectly together", I guess you have it figured out to your satisfaction. But I have continued to muse about it some.
The top of this image shows the plot from Wikipedia of the visibility of the eclipse. The places where the Earth is shown in lighter shades (white) are not
places that were in daylight, but were the places that were in moonlight, I guess, roughly the opposite
of daylight at that time.
I tried using NASA's Eyes visualization tool to get another view of what was going on. I'm not very adept with it. The three images along the bottom are my attempt to look from the direction of the Sun to show it from that perspective. You can see that Mars was in near-perfect opposition and it even looks to me as though the Moon would have appeared to be passing Mars during the event. I hand drew some yellow bars to indicate the Earth's North Pole, quite approximately. If this is accurate, then during the eclipse, to an observer standing at our North Pole, Mars would have appeared to the south of the Moon, or below it. To an observer standing on our South Pole at the same time, they would have also seen Mars to the south of the Moon, but it would have been above it from their view (that is, until they fell off of the Earth, of course
) To an observer from Australia they would have seen this with the Moon setting to their west and the Sun about to rise from the East. To a person in Rio, it happened a while after sunset with the Moon rising in the East. To a person in Europe or Africa, it would have happened in the middle of the night.
The two main effects I see from the different positions on the Earth are (a) the way the person is standing and facing toward the event can differ a lot; and (b) there would be some parallax movement: although both are far away, Mars is much farther than the Moon, so if one quickly zipped a great distance across the surface of the Earth, Mars should appear to move with you
compared to the Moon. (e.g. from both Australia and Brasil, Mars appeared higher in the sky.)
This is all making sense to me to the extent that I have seen photos and considered these facts. It might be interesting to hear how others would describe it, or if there are any other tools that would give good perspectives on it.
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