I Need help from some of you math wiz-bangs. I looked up on a chart of surface brightness that M1 has a surface brightness of 35 * 10 to the minus 6; or .000035. I found a formula for surface brightness (http://en.wikipedia.org/wiki/Surface_brightness) that states S = m + 2.5 * log10A where m is point-magnitude and A is the area in square arcseconds. I went on my planetarium software and measured M1 to be approximately 440” X 260” arcseconds or 114,400 square arcseconds. To further complicate maters I used an Excel spread sheet to do the math for me so I could use it for different objects. Excel is telling me that Log10(114,400) = 5.058, and plugging back into the formula 2.5 * 5.058 = 12.6 and + 8.4 = 21. 21 is a loooong ways from .000035. I figure the problem has to be in the Log10 area of my math. Or, they are saying to different things from which I am confused.