Originally Posted by

**skeske1234** The stellar magnitude scale compares the brightness of stars using the equation **m_2 - m_1 = log(b_1/b_2)**. where m_2 and m_1 are the apparent magnitude of the two stars being compared (how bright they appear in the sky) and B_2 and B_1 are their brightness (how much light they actually emit). This relationship does not factor in how far from Earth the stars are.

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**b) The sun appears about 1.3 x 10^10 times as brightly in our sky as does Sirius. What is the apparent magnitude of the sun?**

I need help on this part.

I subed in m_1 = -1.5 and (b_1/b_2) = (1.3 x 10^10)

and then solved for m_2

m_2 - m_1 = log (1.3x10^10)

m_2 - (-1.5) = log (1.3 x 10^10)

m_2 + 1.5 = log (1.3 x 10^10)

m_2=log (1.3 x 10^10) - 1.5

m_2=8.61

therefore the apparent mag of the sun is 8.61.

However, the back of the book says that it is -11.61.. How do I get it and what did I do wrong?