SOLAR SYSTEM

Detailed explanation-1: -Luminosity is the rate at which a star radiates energy into space. Apparent brightness is the rate at which a star’s radiated energy reaches an observer on Earth. Apparent brightness depends on both luminosity and distance.

Detailed explanation-2: -Luminosity is the quality of something that gives off light or shines with reflected light.

Detailed explanation-3: -The luminosity of the lightbulb is L = 100 W. The brightness is b = 0.1 W/m2. So the distance is given by d2 = (100 W)/(4 Pi x 0.1 W/m2). Since 4 Pi is approximately 10, this is d2 = (100 / 1) m2. Thus d2 = 100 m2. We now know what d2 is. So d = 10 m.