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How to use moon map?

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#1 keroppilee

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Posted 17 January 2013 - 02:12 PM

I use an xt8. Bought Sky and Telescope's Field Map to the moon. Tried to orient myself with the map last night and just could not sort it out. I thought I saw a good landmark but it wouldnt have matched the map flipped upside down. (for newtonians) Any tips?

#2 csrlice12

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Posted 17 January 2013 - 02:14 PM

I honestly can't remember where, but I did see a thread somewhere's that had a link to "reverse" moon maps that were printed up like you would see the moon thru a refractor and a reflector. Anybody remember this one?

#3 keroppilee

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Posted 17 January 2013 - 02:29 PM

I'm pretty sure i bought the right moon map. It's a normal view (binoculars) but newtonians just rotate the image 180 degrees so rotating the map should give the same view.

#4 csrlice12

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Posted 17 January 2013 - 02:35 PM

These maps were specially printed so that it looks like just what you'd see thru the eyepiece of the scopes. For a dob/newt, they were totally flipped, for the refractor, they were just flipped right to left I believe. These were from a vendor, they are not free.

#5 csrlice12

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Posted 17 January 2013 - 02:39 PM

Did a quick search. Here you go! AND, they appear to be free! http://pruss.mobi/moon.html

#6 spencerj

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Posted 17 January 2013 - 02:54 PM

Isn't the view through a Newtonian reversed left to right as well as up and down? Honestly, I don't remember anymore.

With star charts and moon maps, I always look for patterns in the eyepiece that I can match up to the chart or map. Then I move in a known direction from the known pattern to another feature that can be identified. Give it enough time and down and up and left and right lose all meaning.

#7 S.Boerner

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Posted 17 January 2013 - 02:54 PM

Virtual Moon Atlas although you'd need to use a laptop.
http://ap-i.net/avl/en/start

#8 csrlice12

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Posted 17 January 2013 - 03:07 PM

Refractors do a right/left flip. A Newt/Dob is upside down and backwards (don't tell the refractor folks that though)...

#9 SteveNH

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Posted 17 January 2013 - 03:25 PM

Actually, it depends on whether you are using a diagonal or not. Very importantly, on a Newtonian, it also depends on which side of the tube you are standing and how the tube is oriented - horizontally or vertically with respect to your head.

Without a diagonal, as is usually the case, a Newtonian has an even number of reflective surfaces. This means the Newtonian image is right reading and not flopped (but may be rotated depending on where you are standing with respect to the tube). Same is true for an SCT without a diagonal - two mirrors = right reading (not flopped).

A refractor does not flop the image left-right (even number of reflective surfaces; i.e., none). When used with a diagonal though, the image then becomes flopped (1 mirror = an odd number of reflective optics).

Because you usually sit at the end of the refractor to view, it's safe to assume your head will point to the object as you peer through the eyepiece in a diagonal pointing up. Then your view is right side up but reversed left-right.

#10 Tony Flanders

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Posted 17 January 2013 - 04:01 PM

I use an xt8. Bought Sky and Telescope's Field Map to the moon. Tried to orient myself with the map last night and just could not sort it out. I thought I saw a good landmark but it wouldnt have matched the map flipped upside down. (for newtonians) Any tips?


Yes, you're using the right map. It might be nice to have the exact same map with the lettering upside-down, but as far as I know nobody sells such a thing. I predict you'll get used to it soon.

Remember that when the Moon is setting or rising, it's rotated quite a lot. But the line connecting the cusps of the crescent (when it's a crescent) always points almost due north-south. So you have to rotate the map to match that.

The really obvious feature to start with is Mare Crisium. It's hard to miss, since it's a "sea" that's completely cut off from all the others. Once you have that, it should be easy to decipher the rest.

#11 beatlejuice

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Posted 17 January 2013 - 06:56 PM

You might be interested in this little gem, Discover the Moon The maps with highlights for each day of the moons transition through its phases are shown as a mirror image on one side of each page and upside down on the other side of each page so that no matter which scope you are using the appropriate map will match what you see in the eyepiece.
It's a great beginners guide to observing the moon.

Eric

#12 keroppilee

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Posted 17 January 2013 - 07:05 PM

I see so even though the same face always faces us, it's not always rotated the same way? That might explain it....I thought the bottom would always be S and the top always N.

#13 Phred Smith

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Posted 17 January 2013 - 07:27 PM

You might want to check out the Lunar Field Atlas on my website. It's free. There's a version for any type telescope anywhere in the world. You'll either have to print it out or use the interactive version on a laptop in the field.

#14 Tim2723

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Posted 17 January 2013 - 07:45 PM

It is a fundamental skill of the Lunar observer to read upside down and backwards in dim light with annoying reflections on the paper.

#15 mfromb

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Posted 17 January 2013 - 07:54 PM

Thanks to all who have posted links to maps, sites, etc. Some really good stuff there. Especially the large maps with grids, with and without color coding, tags, etc.

Firing up the large format color printer. There goes the "free". :-)

#16 Tony Flanders

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Posted 18 January 2013 - 05:06 AM

I see so even though the same face always faces us, it's not always rotated the same way? That might explain it....I thought the bottom would always be S and the top always N.


No, like everything else in the sky, the Moon rotates as it traverses from east to west. Orion does the same; it rises on its back, straightens out when overhead, and bellyflops back down to the west.

The classic view of the Man in the Moon only makes sense when the full Moon is rising, with north directly to the left.

North is toward Polaris. Only when an object is at its highest due south of you is north directly up.

#17 csrlice12

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Posted 18 January 2013 - 10:08 AM

The reason we only see one side of the moon is that it rotates on it's axis once in the same amount of time it takes it to revolve around the Earth. Imagine the Earth only rotating on it's axis once a year insead of once a day........

#18 killdabuddha

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Posted 18 January 2013 - 12:03 PM

You might want to check out the Lunar Field Atlas on my website. It's free. There's a version for any type telescope anywhere in the world. You'll either have to print it out or use the interactive version on a laptop in the field.


Ah Phred,

So nice to meet summa the folks we "knew" during the build. Yer site was a delight to find as we were puttin everything together. Very nice site/resource and thank you.

#19 Billytk

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Posted 18 January 2013 - 04:50 PM

I see so even though the same face always faces us, it's not always rotated the same way? That might explain it....I thought the bottom would always be S and the top always N.


This is a GREAT video of the Moon as we see it over the course of a year. It wabbles alot.
http://www.newscient...-a-year-in-t...

#20 keroppilee

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Posted 18 January 2013 - 05:22 PM

it makes sense now. i thought i was crazy. i was looking at NW and SW at the same time thinking it doesn't "wobble" and was like *BLEEP*...

#21 Tony Flanders

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Posted 19 January 2013 - 06:18 AM

I see so even though the same face always faces us, it's not always rotated the same way? That might explain it....I thought the bottom would always be S and the top always N.


This is a GREAT video of the Moon as we see it over the course of a year. It wabbles alot.
http://www.newscient...-a-year-in-t...


OK, we're confusing two different things.

The wobble shown on that video is rotation with respect to celestial north. Moon-north isn't quite the same as celestial north due to the fact that the planes of Earth's orbit, the Moon's orbit, and Earth's spin aren't quite the same. This effect is particular to the Moon, but the rotation involved is quite minor.

I'm talking about a completely different kind of rotation -- of celestial north with respect to up and down. This affects everything in the sky, often dramatically. In an extreme case like the Big Dipper, which makes a full rotation around Polaris without ever setting, celestial north makes a full, 360-degree rotation -- equal to up at one time of night and/or year and directly down at another time of night and/or year.

This is why you need to get used to tilting any kind of celestial chart to match the object, whether it's a chart of the Moon's features, Mars's features, or the constellations.






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