File talk:GJ581orbits.svg

Orientation?

Is there a "known orientation" of this system as viewed from earth (face-on like this shows, vs edge-on)? I expect this can be extraplated by the radial velocity variations that the statistical analysis performed. I heard at least it isn't edge-on (no chance for visual eclipsing). Tomruen (talk) 05:12, 1 October 2010 (UTC)

Unfortunately not. Essentially an orbit's orientation can be specified by 3 Euler angles, usually the argument of pericentre (ω), the inclination (i) and the longitude of pericentre (Ω). Radial velocities only give you ω. Unfortunatly since there are no astrometric detections of the planets, the orientation as viewed from Earth is unknown. The direction from Gliese 581 to Earth on this diagram is upwards when projected onto the plane of this diagram, but the actual direction in 3 dimensions is unknown. Icalanise (talk) 19:16, 2 October 2010 (UTC)