Apparently, I don’t know everything

Jacob was having an interesting and quite academic conversation with two of his buddies in the back of my van on the way to a field trip this Spring.

Friend #1: “The sun weighs 60 kabillion million pounds”

Jacob:  “No it doesn’t”

Friend # 2: “Ask your mom how much the sun weighs.”

Jacob:  “I don’t think she even knows that – and she knows a lot”.

By the way, noone knows exactly how much the sun weighs but using Newton’s Laws of motion and Newton’s revision of Kepler’s third law we can estimate the weight based on the following equation:

Mass_of_Sun=((4*pi2)/G) (a3/P2), where pi=3.14159, G is a fundamental constant, a is the radius of the Earth’s orbit about the Sun, and P is the orbital period of the Earth about the Sun.

This gives the value of the Sun’s mass to be about 2 x 1030 kg. (That’s 2 with 30 zeroes after it and that’s kg – to get pounds you’d have to multiple that number by 2.2)  Pretty big!

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~ by jenevangelista on July 9, 2008.

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