Space/Science — HabitableZone

Space/Science » in reply to re: Though I suppose that is what you meant.

re: Though I suppose that is what you meant.
gbaikie — (archived)

"No.

As so often, what he said is what he MEANT, and what YOU read and thought you understood was a bunch of cotton wool dipped in yoghurt.

He said "The Sun's output is so many JOULES PER SECOND" - that's WATTS. Do you want it in BTU/Hr? or Calories per month?"

I'm quite aware that joules per second is equal to watts-
1 joule second equals 1 watt.

But other than measuring the energy from known earth distance or any known distance, I don't know how you arrive at the total solar output of energy.

"It doesn't matter where you measure it, how far away you are, or what hat you are wearing. That's how much energy it is producing. From that, you can calculate everything else you need to know."

Yes, assuming 3.847E+26 J/s is accurate.

Which it probably is or I at least have no reason to doubt it. But Andy brought up solar constant or solar "constant" and solar constant means:
"The solar constant is the amount of incoming solar electromagnetic radiation per unit area, measured on the outer surface of Earth's atmosphere in a plane perpendicular to the rays. The solar constant includes all types of solar radiation, not just the visible light."
http://en.wikipedia.org/wiki/Sunlight

Of course, solar constant isn't constant but varies depending upon the distance the earth is from the Sun:
continuing from wiki:
"It is measured by satellite to be roughly 1366 watts per square meter (W/m²),though this fluctuates by about 6.9% during a year (from 1412 W/m² in early January to 1321 W/m² in early July) due to the earth's varying distance from the Sun..."

To simply use solar constant [1366 watts per square meter] and average earth distance from the sun is NOT precisely correct. I imagine they allowed for this, but as I said, I simply wanted the reference of this number before relying on it as being an accurate number.
And as I said, if they are giving a precise number, I would guess they would take into account the actual variation of the sun output- this variation is small compared to the apparent variation caused by different distance of the Earth from the Sun- but sun does vary in the amount of energy it actually emits from day to day and year to year.

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