Earth is 150 million kilometers from the sun and the apparent brightness of the sun in our sky is about 1300 watts/m2. use these two facts and inverse square law of light to determine the apparent brightness that would measure for the sun if we were located three times earth's distance. 2 suppose a star has the same apparent brightness as as alpha centauri a (2.7 x 10-8 watts/m2 but located at distance of 100 light-years. what is its luminosity? 1 light-year = 9.5 x 1015 m. use scientific notation to input your answer. example 9.5 x 1015e 9.5e15 3 earth is 150 million kilometers from the sun and the apparent brightness of the sun in our sky is about 1300 watts/m2. use these two facts and inverse square law of light to determine the apparent brightness (in watts/m2) that would measure for the sun if we were located one-third earth's distance. input the numerical value, you don't need to add the unit. 4 alpha centauri a lies a distance. of.4.4 light years and has an apparent brightness in our night 2.7 x 10-8 watts/m2. use the inverse square law of light to calculate luminosity of alpha centauri a. 1 light-year = 9.5 x 1012 km = 9.5 x 1015m you can enter your answer in scientific notation. for example to enter 9.5 x 1015 9.5 e15 upper case e should be used. 5 suppose a star has the same luminosity as our sun (l = 3.8 x 1026 watts) but is located at a distance of 7 light years. what is its apparent brightness? 1 light-year = 9.5 x 1015 m put the numeric value only without the unit you can enter your answer in scientific notation. for example to enter 9.5 x 10-9 = 9.5 e-09 upper case e should be used.