posted on Jun, 11 2010 @ 08:19 AM
I find that difficult to believe. All of the long period comets that have been observed to date (that have had their orbits accurately calculated)
have been shown to be gravitationally bound to the Sun. In other words, their orbits are very eccentric ellipses, with eccentricities less than
Quite a few have eccentricities very slightly greater than 1.0 when they are passing through the inner solar system, but that is simply because
of the transition from barycentric to heliocentric motion. Beyond the orbits of the major planets, comet orbital motion is based on the centre of mass
of the Solar System, rather than the centre of mass of the Sun. The giant planets (particularly Jupiter and Saturn) exert an appreciable gravitational
influence on the Sun, causing it to "wobble". It is this shift in the Sun's position that makes it appear as though some comets have hyperbolic
orbits. However, when they leave the realm of the major planets, their orbits are almost always elliptical.
The only comet that is known to have a truly hyperbolic orbit is C/1980 E1 Bowell, and this is because it had a close encounter with Jupiter in
December 1980. The comet passed approximately 34 million kilometres from the planet, and received a gravitational boost sufficient to overcome solar
escape velocity. It is now on a one way trip to the stars.