APOD: Red Planet, Red Moon, and Mars (2018 Aug 09)

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APOD: Red Planet, Red Moon, and Mars (2018 Aug 09)

Post by APOD Robot » Thu Aug 09, 2018 4:13 am

[img]https://apod.nasa.gov/apod/calendar/S_180809.jpg[/img] Red Planet, Red Moon, and Mars

Explanation: Mars is also known as The Red Planet, often seen with a reddish tinge in dark night skies. Mars shines brightly at the upper left of this gorgeous morning twilight view from Mornington Peninsula, Victoria, Australia, but the Moon and planet Earth look redder still. Taken on July 27, the totally eclipsed Moon is setting. It looks reddened because the Earth's umbral shadow isn't completely dark. Instead Earth's shadow is suffused with a faint red light from all the planet's sunsets and sunrises seen from the perspective of an eclipsed Moon. The sunsets and sunrises are reddened because Earth's atmosphere scatters blue light more strongly than red, creating the faint bluish twilight sky. Of course, craggy seaside rocks also take on the reddened colors of this Australian sunrise.

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Ann
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Re: APOD: Red Planet, Red Moon, and Mars (2018 Aug 09)

Post by Ann » Thu Aug 09, 2018 8:40 am

Red planet. Right.

We can broadcast a message to all the ETs out there, encoded in some suitable mathematical language:

You can find us by searching for a planet that reflects an remarkable amount of light in the region of 600 to 700 nm".

Right.

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Re: APOD: Red Planet, Red Moon, and Mars (2018 Aug 09)

Post by Cousin Ricky » Thu Aug 09, 2018 11:16 am

The rock looks like an alligatorduck.

thomas.st

Re: APOD: Red Planet, Red Moon, and Mars (2018 Aug 09)

Post by thomas.st » 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.

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Re: APOD: Red Planet, Red Moon, and Mars (2018 Aug 09)

Post by gmPhil » Thu Aug 09, 2018 2:16 pm

This is one of those photos that needs a banana! The foreground "rock" could be just about any size you imagine….

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Re: APOD: Red Planet, Red Moon, and Mars (2018 Aug 09)

Post by neufer » Thu Aug 09, 2018 2:51 pm

Click to play embedded YouTube video.
gmPhil wrote:
Thu Aug 09, 2018 2:16 pm

This is one of those photos that needs a banana!

The foreground "rock" could be just about any size you imagine….
Art Neuendorffer

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Re: APOD: Red Planet, Red Moon, and Mars (2018 Aug 09)

Post by rstevenson » Thu Aug 09, 2018 4:08 pm

gmPhil wrote:
Thu Aug 09, 2018 2:16 pm
This is one of those photos that needs a banana! The foreground "rock" could be just about any size you imagine….
Bananas are good when photographing a bonsai rock like this, but its actual size can be estimated nevertheless. Zoom into the full size image, then scroll down. You'll see dark seaweed and light chips of what are likely broken shells. This gives us a rough sense of size, as does the frothy wave action to either side of the top of the rock. Based on those clues, I'd estimate this rock at about 6' high, plus or minus about 25%.

Rob

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Re: APOD: Red Planet, Red Moon, and Mars (2018 Aug 09)

Post by neufer » Thu Aug 09, 2018 4:49 pm

Click to play embedded YouTube video.
rstevenson wrote:
Thu Aug 09, 2018 4:08 pm
gmPhil wrote:
Thu Aug 09, 2018 2:16 pm

This is one of those photos that needs a banana! The foreground "rock" could be just about any size you imagine….
Bananas are good when photographing a bonsai rock like this, but its actual size can be estimated nevertheless. Zoom into the full size image, then scroll down. You'll see dark seaweed and light chips of what are likely broken shells. This gives us a rough sense of size, as does the frothy wave action to either side of the top of the rock. Based on those clues, I'd estimate this rock at about 6' high, plus or minus about 25%.
It looks taller than a man to me.
Art Neuendorffer

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Re: APOD: Red Planet, Red Moon, and Mars (2018 Aug 09)

Post by Boomer12k » Thu Aug 09, 2018 7:03 pm

Very nice....

We are having smoke from state and California fires again this year. So very smoky sky...
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Re: APOD: Red Planet, Red Moon, and Mars (2018 Aug 09)

Post by MarkBour » Sat Aug 25, 2018 1:04 am

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.
Capture2.png
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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