Puzzle Description:

A military search light,looking for enemy planes.

#1: Tom King (sgusa) on Jan 7, 2012

Nice puzzle, Aldege. I was thinking it was a headlight on a locomotive. Thanks!

very nice image and a wonderful line logic solve!

Wonderful puzzle Aldege, very fun solve, great idea, I know it's hard coming up with something new to create, I think this must be the only military search light on the site. Thank you :)

Powerful image, Aldege. Fun to solve.

Thx everyone,it is hard coming up with ideas,especially later in the evening when you want to get a last puzzle in before you put the kids to bed,lol. It's also hard to come up with a good title. I wanted to title this"How many lumens",then in the description ask"does it take to light up the sky"? I thought i could make this one of those educational type of puzzles where we all learn a bit from each other,however i couldn't find that information on-line.I found all kinds of history about the first search light,but that wasn't what i wanted at the time.lol. I'm glad the image was illuminating to everyone.:)

Nicely done.

The answer to your question would be very difficult to determine, because it depends on what you mean by "light up the sky" - the sky begins right here in front of my nose. I can see pretty far up into the sky, but it continues far beyond my field of vision.

Also, measuring light is very tricky. I did find an interesting article that explains the difference between radiance (light at the source) and illuminance (light at the point of the object), and how to measure candlepower and lumens.

http://www.theledlight.com/lumens.html

When I googled "searchlight" I found this page that has lots of photos and history. One of the photos (next to last) shows a searchlight from WWII that has been restored. The last photo shows the searchlight as it throws an 800 million candlepower beam at the sky.

http://www.skylighters.org/howalightworks/index.html

If you multiply 800 million candlepowers by 12.5, you get 10 billion lumens! But you would have to read the first link to understand what that means.


Did I do the math right?

LOL probably,but that sounds like an awful lot of lumens,all i know about lumens is that according to Canadian firecode you need at least a certain # of lumens to light the hallways of an apartment building,or else you could be fined.

My first thought when I completed this puzzle and read the description was "Now that I live on the south shore of Lake Ontario, I need one of these to look out for those pesky Canadians invading the US." LOL

Rofl Joel.:)

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