SCIE 1920U Chapter 7: 7 Planets around other stars
Document Summary
Extrasolar planets are planets the lie outside our solar system. All objects in a star system, including the star itself, orbit the system"s balance point, or center of mass. In principle, with sufficiently precise measurements of the sun"s orbital motion made over many decades, an extraterrestrial astronomer could deduce the existence of all the planets of our solar system. This is the astrometric method; in which we make very precise measurements of stellar positions in the sky. If a star wobbles gradually around its average position, we must be observing the influence of unseen planets. The primary difficulty with the astrometric method is that we are looking for changes in position that are very small even for nearby stars, and smaller still for more distant stars. A second method for searching for gravitational tugs due to orbiting planets is the.
