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 Definition/Summary Irradiance is the power per area of the radiation received by a surface. It is measured in SI units of watts per square meter ($W.m^{-2}$), or cgs units of ergs per square centimeter per second ($erg.cm^{-2}.s^{-1}$, often used in astronomy).

 Equations surface area of star: $$4\pi R^2$$ total power radiated (Luminosity): $$L\ =\ 4\pi R^2\sigma T^4$$ power per area at distance d (Irradiance): $$I\ =\ \frac{L}{4\pi d^2}\ =\ \frac{R^2}{d^2}\sigma T^4$$ ($\sigma$ is the Stefan-Boltzmann constant, $5.67×10^{-8} \, W\cdot m^{-2}\cdot K^{-4}$)

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 gabe69 @ 05:06 AM Jul10-11 Who is the nitwit that removed all the exoplanet examples, the practically vandalized the explanation, how do you revert that???

 tiny-tim @ 11:41 AM May12-11 gabe69, you'll find it easier if you use the preview facility in any thread … choose a thread with no replies (I like the Science Jobs ones), click "QUOTE", and do your preview there (remembering to click "Refresh" on your browser each time, to get the LaTeX working properly). That'll save you time, and prevent the Edit Log going into several pages.

 gabe69 @ 12:40 AM May9-11 I don't understand the importance of autolinking, this is the first I have done anything here, but since no one else seems to know these basic formulas or bothers to add it to scientific publications I thought I would share it. Isn't there a way to use the title with sort of split tags, with commas or something. I did as you suggested and added the general definition. I suspect that it still could see some improvement overall.

 tiny-tim @ 04:38 AM May4-11 But, gabe69, you've done all this work, and nobody will ever see it (once it leaves the "ten latest" list) if it doesn't get autolinking. Just chuck in a general definition of "irradiance" (which btw I couldn't give from memory), change the title back, and everything fits!

 gabe69 @ 03:44 AM May3-11 I agree "Irradiance" itself doesn't necessarily include extrasolar planets, ... "If a point source radiates light uniformly in all directions and there is no absorption, then the irradiance drops off in proportion to the distance from the object squared, since the total power is constant and it is spread over an area that increases with the square of the distance from the source." it doesn't necessarily mean stars either. So just because it is in the Astronomy section doesn't mean that "Irradiance" is enough. This is only an in-depth example. "Irradiance of Planets" perhaps.