Re: Closed orbits/WAS Hi Nancy :-))

In Article <Pine.LNX.4.10.10105090208200.955-100000@localhost.localdomain> Axel Harvey wrote:
> On Tue, 8 May 2001, Paul Lutus wrote:
>> 3. All orbits for which n > 2 are innately unstable, chaotic, and are not
>> soluble in closed form as the n = 2 case is.
>
> Thanks. Is this so in the real world, with several-body situations?

Recent articles have pointed out how little man knows about orbits in
the real world.  For example:

A CNN article by Associated Press dated October 23, 1996.
New rebel planet found outside solar system
It's roller-coaster orbit stuns scientists

    A new planet that breaks all the rules about how and where
    planets form has been identified in orbit of a twin star
    about 70 light years from Earth in a constellation commonly
    known as the Northern Cross. The new planet has a roller-coaster
    like orbit that swoops down close to its central star and then
    swings far out into frigid fringes, following a strange egg-shaped
    orbit that is unlike that of any other known planet. "We don't
    understand how it could have formed in such an orbit," said
    William D. Cochran, head of University of Texas team that
    discovered the planet at the same time that a group from San
    Francisco State found it independently.

Associated Press article titled Tiny Planet Discovered Beyond Pluto
June 5, 1997
Theory Suggest More Objects in Solar System

    Astronomers have found an icy miniplanet that orbits the sun
    well beyond Pluto, providing evidence that the solar system
    extends much farther than was once thought. ... At its most
    distant, it wanders three times farther from the sun than Pluto,
    tracing a looping, oblong path into an astronomical terra incognito.

Orbits Of Other Distant Planets Oval - Not Circular
Public Affairs Office, San Francisco State University, January 9, 1999
Ligeia Polidora

    Unlike the nine planets that make circular orbits around our
    Sun, all nine of the 17 extrasolar planets which are in distant
    orbits around their host stars travel in oval-shaped paths. This
    surprising pattern suggests that our heliocentric perspective
    skews expectations of worlds elsewhere. ... Theorists still have
    their work cut out for themselves in explaining how the nine
    extrasolar Jupiter-like planets developed their eccentric orbits.
    Four plausible scenarios have been proposed. One posits that
    when enough large planets orbit a star in close proximity, they
    generate a gravitational slingshot that projects the planets into
    elongated orbits. Another idea is that a passing star rips
    through the heart of a solar system and perturbs planetary
    orbits. The perpetrator could also be an orbiting companion star.
    Sixty-four percent of Sun-like stars have a companion star, and
    HD168443 appears to be part of one such binary pair. (Another
    recently announced extrasolar planet orbits the solitary star
    HD210277, so that planet's elliptical orbit demands a different
    explanation.)