APOD: The Lunar X (V) (2018 Mar 01)

Comments and questions about the APOD on the main view screen.
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APOD: The Lunar X (V) (2018 Mar 01)

Post by APOD Robot » Thu Mar 01, 2018 5:10 am

Image The Lunar X (V)

Explanation: The striking X in this lunarscape is easily visible in binoculars or a small telescope, but not too many have seen it. The catch is, this lunar X is fleeting and only apparent in the hours before the Moon's first quarter phase. Along the shadow line between lunar day and night, the X illusion is produced by a configuration of craters seen here toward the left, Blanchinus, La Caille and Purbach. Near the Moon's first quarter phase, an astronaut standing close to the craters' position would see the slowly rising Sun very near the horizon. Temporarily, crater walls would be in sunlight while crater floors would still be in darkness. Seen from planet Earth, contrasting sections of bright walls against the dark floors by chance look remarkably like an X. This sharp image of the Lunar X was captured on February 22nd. For extra credit, sweep your gaze along the lunar terminator and you can also spot the Lunar V.

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JerryO

Re: APOD: The Lunar X (V) (2018 Mar 01)

Post by JerryO » Thu Mar 01, 2018 6:27 am

The shadow inside the V looks like a rock 'n' roll guitarist a couple hours after the X and V are at their best. I call it the Lunar Elvis and look for it every first quarter. Once you see it at the right phase, it's amazing how much it looks like a guitarist. Head and body are obvious, legs are spread, guitar neck is held high, and the other arm crooks around to strum.

Confused
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Re: APOD: The Lunar X (V) (2018 Mar 01)

Post by Confused » Thu Mar 01, 2018 8:01 am

Is the X closer to being a quarter-circle on top of a Caret (^)? If so then I see it. Is the V near the middle with the bottom line nearly horizontal and the V pointing to the left??

HellCat
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Re: APOD: The Lunar X (V) (2018 Mar 01)

Post by HellCat » Thu Mar 01, 2018 9:07 am

Crater's ...

Not craters' ...

haarkon

Re: APOD: The Lunar X (V) (2018 Mar 01)

Post by haarkon » Thu Mar 01, 2018 9:32 am

Moon is just beautiful. And resolution is nice

Just one question :
There is a long, almost straight, line a bit above the V, any idea of the phenomenon behind ?
Thanks by advance.

peterLl

Re: APOD: The Lunar X (V) (2018 Mar 01)

Post by peterLl » Thu Mar 01, 2018 9:36 am

This picture is a mirror image. Why not print it correctly?

edgardine

Re: APOD: The Lunar X (V) (2018 Mar 01)

Post by edgardine » Thu Mar 01, 2018 11:32 am

peterLl wrote:This picture is a mirror image. Why not print it correctly?
I agree. APOD has a pedagogical purpose, it is a weird idea to show the moon in mirror, especially since many people have trouble figuring out its phases. Don't add another misrepresentation.

mister T
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Re: APOD: The Lunar X (V) (2018 Mar 01)

Post by mister T » Thu Mar 01, 2018 11:45 am

I see a Lunar O!

Tmartin@greensboroday.org

Re: APOD: The Lunar X (V) (2018 Mar 01)

Post by Tmartin@greensboroday.org » Thu Mar 01, 2018 11:53 am

I have a problem with the caption as it indicates that the lunar x is only visible a bit before first quarter... As I have imaged the same feature coming into sunlight a bit after first quarter. This made me re-consider and look back at my previous images. Indeed mine show the same feature but at a greater phase. This is of course due to the libration of the Moon. So clearly at some times, the X can be seen at different phases.
Image taken May of 2016
https://www.facebook.com/photo.php?fbid ... =3&theater

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Ann
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Re: APOD: The Lunar X (V) (2018 Mar 01)

Post by Ann » Thu Mar 01, 2018 12:13 pm

Tmartin@greensboroday.org wrote:I have a problem with the caption as it indicates that the lunar x is only visible a bit before first quarter... As I have imaged the same feature coming into sunlight a bit after first quarter. This made me re-consider and look back at my previous images. Indeed mine show the same feature but at a greater phase. This is of course due to the libration of the Moon. So clearly at some times, the X can be seen at different phases.
Image taken May of 2016
https://www.facebook.com/photo.php?fbid ... =3&theater
I don't have Facebook, and Facebook refuses to let me see your picture. Can you post it here?

Ann
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Tmartin@greensboroday.org

Re: APOD: The Lunar X (V) (2018 Mar 01)

Post by Tmartin@greensboroday.org » Thu Mar 01, 2018 1:17 pm


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neufer
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Re: APOD: The Lunar X (V) (2018 Mar 01)

Post by neufer » Thu Mar 01, 2018 2:13 pm

Click to play embedded YouTube video.
Art Neuendorffer

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Ann
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Re: APOD: The Lunar X (V) (2018 Mar 01)

Post by Ann » Thu Mar 01, 2018 4:51 pm

Tmartin@greensboroday.org wrote:I can't seem to post images directly ...Try this...
https://drive.google.com/file/d/1jQ3196 ... HHgMM/view

and this

https://drive.google.com/open?id=1Sbo-k ... 8q8h30Gw-P
Thanks! :D

Ann
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earthltd

Re: APOD: The Lunar X (V) (2018 Mar 01)

Post by earthltd » Thu Mar 01, 2018 11:28 pm

I found a nice "S" this spring. I'll dig it up and send it in.

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neufer
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Re: APOD: The Lunar X (V) (2018 Mar 01)

Post by neufer » Sat Mar 03, 2018 4:02 am

earthltd wrote:
Thu Mar 01, 2018 11:28 pm

I found a nice "S" this spring. I'll dig it up and send it in.
One generally only sees the "S" during a Supermoon.
Art Neuendorffer