Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: Version 1.0 Netnews CMS/BITNET 5/19/85; site PSUVM.BITNET Path: utzoo!watmath!clyde!cbosgd!ukma!psuvm.bitnet!gms From: GMS@PSUVM.BITNET Newsgroups: net.astro Subject: Re: How long has Halley's Comet been in present orbit? Message-ID: <4143GMS@PSUVM> Date: Fri, 10-Jan-86 13:22:53 EST Article-I.D.: PSUVM.4143GMS Posted: Fri Jan 10 13:22:53 1986 Date-Received: Sat, 11-Jan-86 07:11:57 EST References: 1017@lsuc.UUCP Lines: 29 This really dosen't answer the question of how long P/Halley has been in its present 76-year orbit. I just wanted to point out that there are nongravitational forces which act upon the orbits of comets. The one I read about most often is ourgassing from the comet itself. These forces may accumulate over time and thus make the tracing of orbits into the past less accurate. However, the question does raise another point. If there are bodies beyond the orbit of Pluto, might it be possible, through a study of many trans-Pluto comets to infer where any such massive bodies (planets, brown dwarfs, etc.) might be found? ------------------------------------------------------------------------------- ******* Gerry Santoro ******** * Microcomputer Information & Support Center *********** * Penn State University ******** *** * 101 Computer Building ********** *** * University Park, PA 16802 *************** * (814) 863-4356 ************ * ********* * GMS @ PSUVM (bitnet) ******* ** * santoro @ penn-state (csnet) ***** ** * ...!psuvax1!psuvm.bitnet!gms (uucp) **** * gms%psuvm.bitnet@wscvm.arpa (arpa) *** * *******