# How bright would the moon be, as lightbulb?

sonhouse
Science 03 Feb '18 07:38
1. sonhouse
Fast and Curious
03 Feb '18 07:38
Saw this question in phys.org science forum, now closed.

I thought it would be an easy calc but then realized the reflection from the sun would be a variable across the surface since at the solar horizon, there would be no reflection to Earth so it would be zero to max.

How would you do the math there? If it was a flat surface it would just be the surface times the albedo (~12ðŸ˜µ times 1050 W/m^2 times r^2 (1.707 E6) divide by 2 because only half the moon, I get about 180 TW.

But that wouldn't be the full story since it is not a flat disk. How do you include the variable illumination in the total.

The question was how much light would there be from the moon if it was considered a light bulb, which of course it doesn't have a lot of radiation from itself but can be considered a reflector.
2. 04 Feb '18 03:52
yes, I agree..a light bulb is hollow, just like the moon..
3. sonhouse
Fast and Curious
04 Feb '18 15:031 edit
Originally posted by @ogb
yes, I agree..a light bulb is hollow, just like the moon..
Ah, you don't know about LED's then. If the moon is hollow, why do we still have lunar tides? Seems a big empty ball would not have enough mass to do that and Apollo dudes walked around on the moon so they experienced what, 1/6 Earth gravity so where do you get your info about the moon? Ancient Alien TV show?

About the OP, how do you calculate what the equivalent size of a flat disk that would intercept solar radiation, which is to say a smaller flat disc could represent the amount of total energy given by the sun. How do you calculate that?
4. 04 Feb '18 17:26
Originally posted by @sonhouse
Ah, you don't know about LED's then. If the moon is hollow, why do we still have lunar tides? Seems a big empty ball would not have enough mass to do that and Apollo dudes walked around on the moon so they experienced what, 1/6 Earth gravity so where do you get your info about the moon? Ancient Alien TV show?

About the OP, how do you calculate what th ...[text shortened]... at disc could represent the amount of total energy given by the sun. How do you calculate that?
I think he was joking (at least I hope so)
5. 04 Feb '18 17:372 edits
Originally posted by @ogb
...a light bulb is hollow, just like the moon..
don't be silly; The Moon is flat like the Earth and Sun and the whole universe. So how can it be hollow?
6. 04 Feb '18 21:35
don't be silly; The Moon is flat like the Earth and Sun and the whole universe. So how can it be hollow?
Good point..yes there are theories regarding one dimensional universe..
7. sonhouse
Fast and Curious
05 Feb '18 20:47
Originally posted by @ogb
Good point..yes there are theories regarding one dimensional universe..
How would you swing left and right and up and down and in and out in a one dimensional universe?
8. 05 Feb '18 21:54
Originally posted by @sonhouse
How would you swing left and right and up and down and in and out in a one dimensional universe?
moving left and right is easy because 1D space line goes from left to right.
You don't have to ever leave the 1D space line to move in the other directions because, to go up and down or forward and backwards, you stretch to bend the 1D space line up and down or forward and backwards you are in and thus you move up and down or forward and backwards with the movement of the 1D space line.
(can you spot the flaw in this explanation? )
9. lemon lime
ook ook ahchoo
06 Feb '18 00:03
Originally posted by @humy
moving left and right is easy because 1D space line goes from left to right.
You don't have to ever leave the 1D space line to move in the other directions because, to go up and down or forward and backwards, you stretch to bend the 1D space line up and down or forward and backwards you are in and thus you move up and down or forward and backwards with the movement of the 1D space line.
(can you spot the flaw in this explanation? )
How could up and down be defined in a 1D universe... up and down in relation to what?
10. 06 Feb '18 08:03
Originally posted by @lemon-lime
How could up and down be defined in a 1D universe... up and down in relation to what?
exactly.
11. sonhouse
Fast and Curious
06 Feb '18 21:04
Originally posted by @humy
exactly.
Anyway, what about the math that equates the total solar energy intercepting the moon comparing it to a smaller disk since the moon loses energy as the angle of the lunar surface aims away from the sun till it is at 90 degrees at horizon.