measure of starshine, come on please help me out its greatly appreiciated?

Answer 1

Brightness as seen on earth is called Magnitude.
Brightness as would be seen from orbit around star is called Luminosity.

Answer 2

If you want to convert apparent visual magnitudes into energy or photon flux (units of energy/photons per second per area) I recommend Allen's Astrophysical Quantities (look it up on Amazon or at the library.) You could use this same conversion to estimate the flux of all the stars in the night sky by assuming the 8000 visible stars each have a magnitude of around 5. (Faintest naked eye visible in dark skies is six). Even though the median magnitude is probably 6, since the magnitude scaling is logarithmic (5 is 2.5 times brighter than 6; 1 is 100 times brighter than 6, and the brightest star in the sky, Sirius counts for about 1000 magnitude 6 stars) you are likely safer assuming a mag of 5, or you could bump up the total count to maybe 10,000 and be just as accurate.

Answer 3

The brightness of stars is usually given on the magnitude scale. The brightest star is Sirius at magnitude -1.6. Magnitude is a logarithmic scale on which smaller numbers are brighter, and an increase of 5 magnitudes means 100 times dimmer. Stars dimmer than 6th or 7th magnitude are too dim to see with the naked eye, even in very dark skies.

Magnitude (m) is related to intensity (I) by m = -2.5 log I - 14.2, where I is in lux. The standard conversion to power units is given as 1 Watt/meter^2 = 683 lux. The lux is weighted for the sensitivity of the human eye, so the actual total power flux at a given visual magnitude will vary with the color temperature of the star.

To measure the total energy from a star, astronomers use what is called bolometric magnitude. This relates to flux as f= 2.54 x 10-8 x 10^(0.4m) watts per square meter, where m is the bolometric magnitude. Bolometric magnitude is approximately equal to visual magnitude for G type stars, and is lower (brighter) for other stars as more of their energy is in the ultraviolet or infrared range.

Or, to put it in simple terms, there's no simple answer.

Answer 4

3 inches