Assume that the sun orbits the center of the galaxy at a speed of 220 km/s and a distance of 26,000 light-years from the center.
calculate the circumference of the sun’s orbit, assuming it to be approximately circular. (remember that the circumference of a circle is given by 2πr, where r is the radius of the circle. be sure to use consistent units. the conversion from light-years to km/s can be found in an online calculator or appendix, or you can calculate it for yourself: the speed of light is 300,000 km/s, and you can determine the number of seconds in a year.)
calculate the sun’s period, the “galactic year.” again, be careful with the units. does it agree with the number we gave above?