APOD: Direct Projection: The Moon in My Hands (2022 Feb 28)

Comments and questions about the APOD on the main view screen.
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APOD: Direct Projection: The Moon in My Hands (2022 Feb 28)

Post by APOD Robot » Mon Feb 28, 2022 5:08 am

Image Direct Projection: The Moon in My Hands

Explanation: You don't have to look through a telescope to know where it's pointing. Allowing the telescope to project its image onto a large surface can be useful because it dilutes the intense brightness of very bright sources. Such dilution is useful for looking at the Sun, for example during a solar eclipse. In the featured single-exposure image, though, it is a too-bright full moon that is projected. This February full moon occurred two weeks ago and is called the Snow Moon by some northern cultures. The projecting instrument is the main 62-centimeter telescope at the Saint-Véran Observatory high in the French Alps. Seeing a full moon directly is easier because it is not too bright, although you won't see this level of detail. Your next chance will occur on March 17.

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Re: APOD: Direct Projection: The Moon in My Hands (2022 Feb 28)

Post by orin stepanek » Mon Feb 28, 2022 12:55 pm

MoonHands_Graphy_960.jpg
What a wonderful Idea for looking at bright
objects! I'm not sure bi want to look at the sun
like that though! :mrgreen:
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Re: APOD: Direct Projection: The Moon in My Hands (2022 Feb 28)

Post by Chris Peterson » Mon Feb 28, 2022 2:05 pm

orin stepanek wrote: Mon Feb 28, 2022 12:55 pm MoonHands_Graphy_960.jpg
What a wonderful Idea for looking at bright
objects! I'm not sure bi want to look at the sun
like that though! :mrgreen:
Well, the Moon isn't really that bright through a telescope. It just seems that way because you're normally pretty dark adapted when you first look, so it dazzles. They make neutral density filters, but if you talk with experienced observers, the best way to view the Moon is through an unfiltered eyepiece. You'll see more detail that way than by projection, or if you use a filter.

Before all the big solar telescopes converted to digital imaging, this kind of projection was the normal way the Sun was studied. I remember this kind of setup when I worked at Big Bear Solar Observatory, and I've seen it operate at Kitt Peak.
Chris

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Re: APOD: Direct Projection: The Moon in My Hands (2022 Feb 28)

Post by Stargeezer » Mon Feb 28, 2022 2:28 pm

My best views of the full (or near full) moon are via binoviewers. The moon takes on an almost 3D appearance and there is no difference in brightness between my eyes, so no dazzling or eye strain.

Starman2233

Re: APOD: Direct Projection: The Moon in My Hands (2022 Feb 28)

Post by Starman2233 » Mon Feb 28, 2022 2:31 pm

Can anyone tell if they're using prime focus or eyepiece projection? The distance seems great enough that I would think prime focus.

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Re: APOD: Direct Projection: The Moon in My Hands (2022 Feb 28)

Post by Chris Peterson » Mon Feb 28, 2022 2:34 pm

Stargeezer wrote: Mon Feb 28, 2022 2:28 pm My best views of the full (or near full) moon are via binoviewers. The moon takes on an almost 3D appearance and there is no difference in brightness between my eyes, so no dazzling or eye strain.
Yeah, good point about both eyes. One of the things that makes lunar viewing somewhat uncomfortable with an eyepiece is the huge loss of dark adaptation on one side only. When you back away from the scope, the imbalance makes you feel blind in one eye, or like you're having a stroke or something! Binoviewers are good for telescopic viewing of everything. You're doubling the signal to your brain.
Chris

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Re: APOD: Direct Projection: The Moon in My Hands (2022 Feb 28)

Post by Chris Peterson » Mon Feb 28, 2022 2:44 pm

Starman2233 wrote: Mon Feb 28, 2022 2:31 pm Can anyone tell if they're using prime focus or eyepiece projection? The distance seems great enough that I would think prime focus.
The telescope has a 9 m focal length, so the prime focus size of the Moon is about 80 mm. Has to be eyepiece projection... and you can see the eyepiece in the image.
Chris

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Re: APOD: Direct Projection: The Moon in My Hands (2022 Feb 28)

Post by JohnD » Mon Feb 28, 2022 3:51 pm

"called the Snow Moon by some northern cultures" No they don't.
Even the link says "Some North American tribes named it the Hunger Moon" and lists some other fanciful names without any attribution.

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Re: APOD: Direct Projection: The Moon in My Hands (2022 Feb 28)

Post by Chris Peterson » Mon Feb 28, 2022 4:06 pm

JohnD wrote: Mon Feb 28, 2022 3:51 pm "called the Snow Moon by some northern cultures" No they don't.
Even the link says "Some North American tribes named it the Hunger Moon" and lists some other fanciful names without any attribution.
Well, it's commonly called that by many North Americans, so I'd say the comment is accurate.
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Re: APOD: Direct Projection: The Moon in My Hands (2022 Feb 28)

Post by orin stepanek » Mon Feb 28, 2022 4:44 pm

Thanks Chris: your insight helps make it all easier to understand! :)
Orin

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Re: APOD: Direct Projection: The Moon in My Hands (2022 Feb 28)

Post by Fred the Cat » Mon Feb 28, 2022 5:20 pm

Using the telescope to project the image onto a spherical screen you'd need a complex complex. :yes:
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Re: APOD: Direct Projection: The Moon in My Hands (2022 Feb 28)

Post by MarkBour » Mon Feb 28, 2022 10:58 pm

JohnD wrote: Mon Feb 28, 2022 3:51 pm "called the Snow Moon by some northern cultures" No they don't.
Even the link says "Some North American tribes named it the Hunger Moon" and lists some other fanciful names without any attribution.
Are you an expert in North American Native cultures?
The link goes to an article that says:
Capture2.png
So yes, they are saying that many of them called it the "Snow Moon".
More reinforcing detail is at: https://www.farmersalmanac.com/february ... moon-18217
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Re: APOD: Direct Projection: The Moon in My Hands (2022 Feb 28)

Post by Sa Ji Tario » Tue Mar 01, 2022 4:18 am


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Re: APOD: Direct Projection: The Moon in My Hands (2022 Feb 28)

Post by JohnD » Tue Mar 01, 2022 3:19 pm

And your evidence is the "Farmers Almanack"?
That would be funny if this was a Snark we're hunting!

And the link to the Wiki page leads to this statement: "Since the introduction of the solar Julian calendar in the Roman Empire, and later the Gregorian calendar worldwide, people no longer perceive month names as "moon" names."

John

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Re: APOD: Direct Projection: The Moon in My Hands (2022 Feb 28)

Post by Chris Peterson » Tue Mar 01, 2022 3:26 pm

JohnD wrote: Tue Mar 01, 2022 3:19 pm And your evidence is the "Farmers Almanack"?
That would be funny if this was a Snark we're hunting!

And the link to the Wiki page leads to this statement: "Since the introduction of the solar Julian calendar in the Roman Empire, and later the Gregorian calendar worldwide, people no longer perceive month names as "moon" names."

John
Again, this is rubbish. My culture, which is certainly North American, most certainly adopts named moons.
Chris

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