I'm not good at this stuff, so I need some help from some smarter people... The speed of the Sun in its orbit about the Galactic center is 220 km/sec. Its distance from the center is 8500 pc. Assuming that the Sun's orbit is circular, calculate the mass of the Galaxy (in solar masses) interior to the Sun's orbit from Kepler's Third Law. Recall that the circumference of a circle is 2 pi r, where r is the radius. Remember that 1 pc is 206265 AU and 1 AU is 1.5x10^8 km. Any help would be greatly appreciated!!!