Hi,
I haven't put too much thought into this, but has wondering if during solar eclipses is the dark side of the moon lite up?
Can anyone shed some light on this for me?

Welcome to the BAUT Forum.

Shed light. I get it.

Yes. The "dark" side is illuminated just like the near side. During a solar eclipse, when the Moon is between the Sun and the Earth, the far side, the "dark" side, is fully illuminated by the Sun. And, the near side is in complete shadow and appears dark.

Part of the problem is that there is a secondary, less common, meaning to "dark": hidden, secret. That's what it means applied to the Moon. The dark side doesn't lack light. It is hidden from us.

It might be best to call them the near and far sides, but the tradition of calling the far side the "dark side" is old and strong.

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The "darkside of the moon" is a rather stubborn misnomer. There simply is no "darkside".

BA has a good note on this: http://www.badastronomy.com/bad/misc/dark_side.html

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---"Why do things have to suck so bad?" a friend once asked me.
"Because space is a vacuum and that's a lot of suck." I replied.
(Actual quote)---

Even the BA, I wish, would stop saying this. It ignores the fact that "dark" has more than one meaning. It's bad English.

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Thanks, I had heard it refereed as perpetually dark in Episode 80: Craters of Astronomy Cast and questioned it. Thanks for your help!

Still, the non-literal meanings are so rare in any context like this that the designation is pedagogically terrible, and those of us regularly teaching beginners would shed no tears were the phrase to be completely replaced by "far side".

I haven't listened to that episode, but I would suggest a couple of possibilities: Either this is an issue of confused terminology, or they were talking about the occasional crater with areas that are never reached by sunlight. I would never refer to the far side of the moon (the part we don't see from Earth) as the "dark side." It's just too confusing. If I'm talking about the "dark side" (a term I usually avoid) I'm referring to lunar night, so by definition, that part of the moon wouldn't be in sunlight. Of course, we often see part of the moon in lunar night, its "dark side."

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I say there is an invisible elf in my backyard. How do you prove that I am wrong?

Disclaimer: Avatar is not an official NASA image and does not imply any specific interplanetary or interstellar capability.

The Leif Ericson Cruiser

Replaced? Me, too. That is one thing. But, to say that "dark side" is wrong, is wrong.

It's not that rare. There are still dark secrets, and I've been kept in the dark, as recently as my last surprise party. There is the slightly archaic (and eurocentric) but still familiar to most, darkest Africa. Ever heard of a dark horse? The Dark Ages? It's not always about illumination.

And did I mention the Moon has a dark side?

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I don't mind calling it the dark side, although I usually go with far side unless someone doesn't recognize that.

After all, it is the one surface we can't even try to image from earth orbit.

The “far side” is perpetually facing away from the earth, so we never get to see it. As the moon swings around the earth in its orbit, which takes about 27.3 days, it always keeps one side aimed at the earth, and the other side always faces away from the earth. However, both sides eventually face the sun every month.

When we don’t see the moon at all, just before it becomes a new moon, a new crescent moon, the far side is mostly lit up at that time, but we can’t see it.

When we see a “half moon”, half of the side facing us is lit by the sun, and half of the other side is lit by the sun (but we can’t see that other side from the earth).

http://en.wikipedia.org/wiki/Moon

It's ambiguous. You might refer to the far side as the dark side, but I'll refer to the unlit side as the dark side, and far too many people think that the far side is always dark.

So, sorry, but I think it is a very poor usage of the term. Most people intuitively understand that the dark ages weren't years without sunlight. That's not the case with the moon.

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I say there is an invisible elf in my backyard. How do you prove that I am wrong?

Disclaimer: Avatar is not an official NASA image and does not imply any specific interplanetary or interstellar capability.

The Leif Ericson Cruiser

I love ambiguity. Art is ambiguous. Life is ambiguous.

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Well said, and I agree. About the dark side of the moon, it's precisely because of the ambiguity that we get to talk to each other about these kinds of things. Since we're humans and not computers, I think it's a good thing to talk about things that might seem silly.

BTW, just as an additional piece of data for the OP, my intuition is that since the moon orbits the earth every 29 days or so, and the moon is tidelocked, the length of one day (cycle of day and night) on the moon is about 29 days. So the sun rises very slowly by our standards.

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As above, so below

It is the dark side not, but the far side!
Too many dark siders already, have we. Hmmmmmm.

US constellation program! Come to the dark side!

I'm with 01101001 on this, the ambiguity is what gets people to actually think about it.

For those who appreciate a good moving picture, here's a Flash animation of the moon illustrating its two sorts of dark sides: Nebraska Astronomy Applet Project: Lunar Phase Simulator

Watch the Moon take a tour around the Earth. Keep in mind that it always keeps the same face pointing at Earth, like a subject walking around his king.

1) Notice how some constantly changing half of it is always not illuminated.

2) Notice how its hidden, distant side from Earth is sometimes not illuminated and sometimes fully illuminated -- and everything in between.

(Speaking of movies, The Dark Knight -- who doesn't just avoid illumination, but dresses in black, has secrets, hides, is sinister, and broods -- might help us embrace the many meanings of "dark".)

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I disagree. I think very few people do think about it, and while "dark" can also mean "hidden," that's not what most people mean. Most people that I know, and I know quite a lot of intelligent people, still think the "dark side" receives no light. "Far side" is a better term.

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Gillian

"Now everyone was giving her that kind of look UFOlogists get when they suddenly say, 'Hey, if you shade your eyes you can see it is just a flock of geese after all.'"

"You can't erase icing."

"I can't believe it doesn't work! I found it on the internet, man!"

I came across a similar issue recently with the word "police" a boyscout troop was asked for volunteers to "police" the area where a festival was being held. There were several very eager volunteers who were very disappointed to find out that they were picking up trash, and not arresting perps.

Here's my stab at Yoddish:

Dark side, it is not, but far, it is.
Already too many dark sides, we have. Hmmmm....

Here's an Internet Yoda Speak translation:

"The far side, it is, not the dark side. To many dark sides, we already have. Hmmmmmm."

Although, given the fact that the site is maintained in the UK, I can't for the life of me how they managed to keep the British accent out of it...

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I am Mugs, of the Alien clan of Usa, Nordamerica, a Terran, of Sol.

Mine: "Perception isn't reality. It's merely an abstraction thereof, and quite often not a very good one at that."

Heinlein's: "Staying young requires the unceasing cultivation of the ability to unlearn old falsehoods." "Freedom begins when you tell Ms. Grundy to go fly a kite."