Can a nuclear blast be seen from the moon?

Getting back on topic, of course you could see a nuclear detonation on the Earth from the moon, and vice versa. For a second or so, an area on the order of a kilometer or more would be brighter than the surface of the sun.

Dating back in the middle ages, there is a written report by a member of the clergy, a monk iirc. He describes a bright point of light dimming to red followed by a spreading dark cloud on the moon. Most likely a moderate sized meteor strike, which would be roughly equivalent visually to a small nuke.

 

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Only-Me, I'm pretty sure the very nastiest of arguments involving all of politics, God and the skinning of puppies doesn't deserve this many exclamation points. Breathe...

I agree with you though. If a shirt has 10% of the original dirt on it after using XYZ detergent we should not say that it's "1000% cleaner!!!!". The problem is that marketing departments like BIGGER numbers rather than smaller ones.

 

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if light is view from d and also from D, where D = 2d its intensity is 4 times lower (or 4 times reduced at D) than at d. It is not totally extinguished as you assert but is 25% as stong.

As I said in the first reply to your post 7 there is a difference between a reduction factor and the percent reduction. There are two valid ways to descibe this 4 times reduction: You can say that there has been a 75% reduction or that the strength is 4 times less. (or 71,000 times less in the viewing from the moon case)

If B is 1 and A =4, then it is valid to say: "B is 4 times smaller," "B is 4 times lesser," & "B is 4 times reduced etc. compared to A."

Or B is 25% of A.

The original post you complained about does not use the "percent form" to tell the reduction. It uses the equally valid "factor form" Your error is to not realize the factor form exists. Or perhaps only to think / assume that factors can not be less than unity.

You seems quite willing to say:"A is 4 times greater than B" but not the converse. I.e. think it wrong to say: "B is 4 times smaller than A." Why?
The original post said the light at the moon was 71,000 times smaller (dimmer) than at the point on Earth - nothing wrong with that.

 

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Hi Read-Only,
It's a trivial and unambiguous idiom. You should be taking it 10 times less seriously than you are.

 

Also note that the Captain said:

The words "You CANNOT reduce anything by 71,000 TIMES it's original value." are your invention - and are not with a clear meaning as what was actually said.

There is absolutely nothing wrong with saying: "a light at D is 71,000 times dimmer than at d" where D >>>> d.

No that is NOT "precisely what the original statement actually says." That is your confused and un clear fabrication.

 

@Billy
If the fraction is small, people will generally express it as the fraction.
You wouldn't say "John is two times smaller than Bill", you would say "John is half the size of Bill".

As the number goes up, the first method is used more often.
I don't think it is wrong, but googling it, I can see it has been discussed quite often, and mathematicians in particular don't like it.

Probably best avoided. If only to avoid a needless argument.

 

I agree completely, but when the ratio is 71,000 the "first method" is the ONLY method, not just a "used more often" method.

There is no word like "half" in the English language for the fraction (1 / 71,000 ) as there is for the fraction (1/2). Thus, it is not possible to use the "second" or named fraction method.

 

I have a feeling you are talking about looking directly at Venus. Illuminance is more like how well you would be able to read the paper at night with Venus as the only source of light.

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Yes, he's talking about looking directly at Venus, just like the thread is about looking directly at a nuclear blast.

The perceived brightness of a point source depends on how much it illuminates your eye.

Venus illuminates your eye on Earth with 0.00014 lux.
A nuclear detonation on Earth would illuminate your eye on the Moon with 0.015 lux.

 

On the other hand, if you had a hundred nuclear explosions going off together in the same place on earth, you would experience an initial flash of 1.5 lux from your seat on the Moon, and could read a newspaper for a fraction of a second.
Perhaps just enough time to read the Title.

If you set off all the nukes in the world, at set intervals, you might just read a paragraph.

 

perfect - thank you everyone, this is just the information I was looking for.

 

If it is brighter we multiply.
If it is dimmer we divide.

That is the convention. The Kaptain was correct in his usage as was Billy T is his defence of it.

Adopting an arrogant posture does not make you correct Read-Only, but I don't expect you to understand that.

 

Hang on, Oph, I wasn't being arrogant in the least. Simply trying to point out that reducing something one TIMES one leaves exactly nothing. And saying something is LESS (as in dimmer) by 17,000 TIMES is indeed ignorant usage of both the English language AND mathematics. (Bear in mind the actual context of the original statement - perhaps read it again?)

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I would agree with the statement if it had said 1/17,000 times but not as it was written.

 

A good idea. You need to RE-READ as original does NOT say light at moon is 17000 times REDUCED (YOUR misreading or fabrication to then be critical of). Here is what it said:

"...{post4} The explosion seen from the moon would be 71,000 times dimmer than from Honolulu. "

I.e. the original said: "71,000 times DIMMER."

Agreed very little light remains. More would have remained if statement were "3 times dimmer." For example as in the statement:

The illumination given by one 100W bulb is three times dimmer than if three 100W light bulbs are used.

To call others names (who are correct, when you are wrong) is arrogant. Perhaps you want to reconsider this post and appoligize?

If A is "one times dimmer" (or "one times brighter") than B is a strange way to state that that A & B are giving the same light intensity. Not as you falsely claim: "ONE times dimmer would leave you with nothing at all to see!!"

If statement is: "A is X times dimmer than B" and X = 2 then A is givining 50% as much light as B.
If X = 1.01, then A is giving 99% as much light as B.

In the limit as X approaches 1, then A is giving the same (or 100% of the) light of B.

Consider again who is the simpleton, "obviously ignorant math-wise"

 

Woah, I don't think this has anything to do with people being ignorant on either side of the issue. It's more a semantic thing, and I happen to agree with Only-Me (but I can also understand your position, Billy).

When we say "X is 5 times brighter than Y" there is no ambiguity, because "brightness" is a measurement with a scale endpoint of zero. "X is 5 times dimmer than Y" only makes sense because we choose to interpret it such that we know what the speaker meant. The scale of "dimness" has no fixed scale endpoint. What units does "dimness" come in? How "dim" is 10,000 lux? No, you don't say "5 times dimmer", but rather "1/5th as bright".

Captain Kremmen's point is valid. We do not say "John is twice as short as Bill" because shortness has no (finite) fixed endpoint, whereas height does. Again, what units do we measure "shortness" in?? haha

Same thing with clean, as I said before:

In the end it's a semantic thing, based on convention, with a few of us on each side of the aisle; nothing to call people names over.

 

Brighter and dimmer are both relative terms – inherently a comparison of one source to another. Brightness and dimness are nouns and not well defined. They have no well defined units and are NOT terms making any comparison. (Nouns never do.)

No one was speaking in these noun terms until the original clear statement was twisting and then criticized.

“A is 50% dimmer than B” & “A is 2 times dimmer than B” & “A is half as bright as B.” all express correctly the same idea.

What is not so clear is: “A has twice the dimness of B.” and “A has half the brightness of B” as here you are using the nouns, brightness and dimness, in an effort to make a comparison. This makes no more sense than A has twice the blueness (or fatness etc.) of B. etc.

One does not use nouns in a comparison of A & B. On uses relative terms (brighter or dimmer; fatter or slimmer, etc.), not nouns, although admittedly this poor English grammatical construction is usually understood.

 

I'm afraid I disagree, and I've already explained why. Brightness DOES have a unit of measurement (the lumen), so I'm not sure why you would even say that. So do the following: tallness (height), hotness (temperature), quickness (speed or acceleration), smartness (IQ), fatness (weight). They are all absolute measurements bound to a scale.

Now, please contrast that with the LACK of measurement units or scale for the following: dimness, shortness, coldness, slowness, dumbness, and skinniness.

Also, I'd like to point out that by saying

...you've moved away from being semantically eccentric to technically WRONG. 'A' cannot be 50% dimmer AND half as bright as 'B' in any sort of logically-consistent manner. If that were true then "200% dimmer" and "200% brighter" would mean the same thing!

 

As I stated earlier the difference is because English does have a word meaning 0.5 but not one for (1/71,000).

English does have some words for large factors (million, trillion, etc) so it is easy to say: "A is million times brigher (or dimmer)" but not as easy to say 1,003,467 or 71,000 times dimmer, etc. However, saying A is 71,000 time dimmer (as in the original statement) is the most compact way to express this relationship in English. Better than: the light is down by a factor of 71,000 times. Or the light is only (1/71,000) times as bright, etc. "71,000 times dimmer" - three words - is the best you can do in English.

Plato had no Greek word meaning cubed. - It took him nearly a paragraph to state that something was the cube of something else (and still Greek scholars do not all agree that is what he was saying). How easy or hard it is to tell the size relationship between A & B stongly depends on what special words are in your language.

 

No A can be 99% dimmer, but not 200% dimmer, but A can be 2 times dimmer, as in:

The light produced by case A (one 100W light bulb) is two times dimmer than that produced by case B (two 100W light bulbs).

I.e. as I said: case A is 50% dimmer, or twice as dim, or half as bright as case A.