A mathematical analysis of the virial theorem can be found at http://astrosun.tn.cornell.edu/courses/astro201/vt.htm
... - 3rd century - 4th century Decades: 190s 200s 210s 220s 230s - 240s - 250s 260s 270s 280s 290s Years: 237 238 239 240 241 - 242 - 243 244 245 246 ...