103/Hartley 2 Meteor Outburst?Date: Tue, 28 Oct 1997 01:38:03 +0000 To: firstname.lastname@example.org, email@example.com From: Steve Harrison, Ko0u/1 Subject: [HSMS] (meteorobs) 103P/Hartley 2 Meteor Outburst? Thought this might be of interest to meteor freaks. It seems to be saying that a prediction of a possible shower this coming weekend by a highly-respected authority does not appear to be a real possibility. Nevertheless, any rocks are better than no rocks, right? 73, Steve Ko0U/1 >Date: Mon, 27 Oct 1997 10:30:15 -0500 (EST) >From: Skywayinc >To: [snip] >Subject: (meteorobs) 103P/Hartley 2 Meteor Outburst? >[snip] > The advisory for a possible meteor outburst from Peter Jennniskens of NASA/Ames (California) for this weekend is certainly of some interest. . . however, for those hoping for something even along the lines a display similar to one of the principal annual showers, a few facts must be noted: First. . . prior to December 1993, 103P/Hartley2 was traveling in an orbit where its perihelion was located inside Earth's orbit. . . a distance of 0.95 AU from the Sun. In late December 1993, this comet passed to within 0.37 AU of Jupiter. This caused its period to lengthen slightly from 6.26 to 6.39 years and placed its perihelion outside the Earth's orbit at a distance of 1.031 AU from the Sun. Thus, the upcoming apparition will be the very first one for 103P/Hartley 2 traveling along this "new" orbit. So. . . when the Earth makes its closest approach to the comet's descending node and perihelion point next weekend (as noted by Dr. D.K. Yeomans) we should assume that there is no chance of any encounter of meteoric debris that has been shed from any previous apparition. In fact. . . for a meteor shower of any intensity to occur, we must hope that there is a fair amount of cometary debris that is traveling well out ahead of this comet. . . and well off its orbit and at least 0.04 AU toward the Sun; a tall order even for a dusty and intrinsically large and bright object (like a P/Halley or P/Swift-Tuttle!). With a smaller, fainter object like 103P/Hartley 2, this would likely be a difficult criteria to fulfill. A more interesting set of circumstances will accompany this comet on its return to the Sun in October 2010. My findings indicate that 103P/Hartley 2 will pass to within only 0.11 AU of Earth (perigee October 22-23). Perihelion comes on October 28. The Earth will arrive at the comet's descending node on November 2, a mere 7 days after the comet (!); similarly, the Earth will pass the perihelion point of the comet's orbit on November 3 -- again just 7 days after the comet! Unfortunately, by 2010, the comet's perihelion distance will have increased to 1.058 AU, meaning that the orbits of the Earth and comet will be separated by nearly 0.07 AU (approximately 10 million kilometers). Thus, although the linear distance between Earth and comet is tantalizing, the gap separating the respective orbits "could" negate any significant activity. On another note, my findings also show that 103P/Hartley 2 in late October 2010 should briefly become an easy naked-eye object. . . perhaps in the 3.5 to 4.0 magnitude range. . . as it slides rapidly south and east through the stars of Auriga and Gemini. I have utilized the 1997 orbital elements for 103P/Hartley 2 which appear on page 189 of the 1997 Observer's Handbook of the RASC to provide the following osculating elements for the 2010 return (non-gravitational forces neglected): For 2000.0: T = 2010 October 28.22 UT Argument of Perihelion = 181.21 Degrees Longitude of Ascending Node = 219.57 Degrees i = 13.62 Degrees q = 1.058 a.u. e = 0.6951 P = 6.49 years Joe Rao Skyway, Inc.
Comments: Rein, W6/PA0ZN