This came up on another web site I read, and it got me to wondering, so I am certain someone here could answer this. The sun is constantly losing mass, as it converts its mass to energy. As it loses mass, its gravitational field weakens, because the gravitational field of a body is directly related to its mass. The gravitational field is what holds the planets in orbit around the sun. At some point, the mass of the sun decreases to a critical level, at which the sun's gravitational field is too weak to hold the planets in orbit any more, so they would just leave orbit and fly off into space. When does this happen? Has anyone tried to calculate this? Or does some other event intervene before this happens? Thanks for any answers or insight.