koolish@bbn-cd.arpa (10/02/84)
From: Dick Koolish <koolish@bbn-cd.arpa> Japanese amateur Tsutomo Seki is reported to have photographed Halley's comet, becoming the first amateur astronomer to do so. The comet is magnitude 20.5 located at RA 6h 46m, DEC +13.0. Seki is a well known comet hunter, having discovered six comets.
gino@voder.UUCP (Gino Bloch) (10/05/84)
[this line is ephemeral] I would like to take this opportunity to bring up, as I do every 75 or 76 years, that the name Halley rhymes with alley; the first syllable is NOT hail. Obsessively compulsively yours, -- Gene E. Bloch (...!nsc!voder!gino)
space@mit-mc (03/29/85)
From: Andrew V Royappa <avr@Purdue.ARPA> Well, I don't know about you, but I certainly have been waiting a while for Halley's Comet to arrive. Shouldn't it be here this year or the next ? Could anyone give precise dates, and if possible info about locations to watch it from. Thank you, Andrew Royappa @ Purdue
don@umd5.UUCP (03/30/85)
> From: Andrew V Royappa <avr@Purdue.ARPA> > > Well, I don't know about you, but I certainly have been > waiting a while for Halley's Comet to arrive. Shouldn't it > be here this year or the next ? Could anyone give precise > dates, and if possible info about locations to watch it from. [] Halley's Comet should be visible this winter until April or May 1986. For the latest up-to-the-minute information on Halley's Comet one may call (long-distance for most) the National Bureau of Standards/ Naval Observatory computer bulletin board (300/1200 baud, even parity) at (202) 653-1079 (Washington, DC) The bulletin board contains press releases and is open to the public. -- ------------------------------------------------------------------------ "Space, the final frontier .." Final, hell! It's the ultimate frontier!! ------------------------------------------------------------------------ -Chris Sylvain ARPA: don@umd5.ARPA BITNET: don%umd5@umd2 CSNET: don@umd5 UUCP: {seismo, rlgvax, allegra, brl-bmd, nrl-css}!umcp-cs!cvl!umd5!don
rg@kitc.UUCP (R. Gilbert) (09/06/85)
Can anyone answer the following questions on Halley's Comet? 1) What is it composed of? 2) How big is it? It's tail? What does it weigh? 3) How often does it visit the earth (precisely)? 4) How close does it come to the earth? 5) What does it orbit? 6) How was it created? 7) How hot or cold is it? 8) How bright is it? Any other bits of data you can think of. Thanks, Bob Gilbert
jamesp@dadla.UUCP (Jim Perkins) (09/11/85)
Dear Bob Gilbert, and others on the net curious about Halley's Comet: >Can anyone answer the following questions on Halley's Comet? >1) What is it composed of? A comet consists of a nucleus of solid matter, a halo of vaporizing ices expelled from the nucleus, and a tail of gaseous matter. The nucleus consists of ices of all varieties -- water ices, methane ices, ammonia ices, small rocks (probably) and a lot of dust. The halo is composed of chunks of ice and vaporized ices, expelled into space. The tail consists of these ices after they have been vaporized by the heat of the sun. The tail always points away from the sun, as the charged particles of the solar wind (these are hot particles ejected from the sun, happens all the time, but especially during solar flares) blow the ices outward from the sun. The tail also has free radicals floating around in it, such as cyanide (CN) and hydroxide (OH), which are caused by particles of the solar wind bombarding the tail and breaking the molecules of vaporized ice into pieces. These caused a big to-do in 1910 when Halley's Comet last visited the Earth -- spectrometers revealed the poisonous cyanide in the tail and people everywhere thought the inhabitants of the Earth would perish. Entrepeneurs sold gas masks and pills, and people had wild bacchanalian parties in what they felt were their last days. Alas, if they had only listened to the scientists, who had said that the concentrations of the poisons were so small that they would have no effect on Earth lifeforms. >2) How big is it? It's tail? What does it weigh? The nucleus is probably about 20-30 miles in diameter, roughly spherical, weighing around 4/3 * pi * (40km)^3 * (1 g * cm^-3) = 2 x 10^17 kg (Unless I calculated wrong), the halo is perhaps a couple thousand miles in diameter, and its tail can reach 100 or more million miles in length. >3) How often does it visit the earth (precisely)? Halley's comet visits the inner solar system every 75-80 years, the period of its orbit is not precise because it is perturbed by gravitational influences of the planets, particularly large planets like Jupiter and Saturn ("perturbation" means the orbit is pulled into slightly different shapes). Reports of Halley's comet have been tracked back to 164 B.C. on Babylonian Tablets and (not-so-reliably) to 240 B.C. on Chinese records. Its last visit was in 1910, 75 years ago. The comet will be visible from Earth from November, 1985 to about May, 1985 (Or is it March; anyway, I'm close). >4) How close does it come to the earth? In 1910 the Earth passed through the comet's tail, but that will not happen this time. In fact, the comet is not going to come very close to the earth, only several tens of millions of miles away (I don't know the exact distance). The fact that the Earth is far away from the comet or that the comet is coming in the winter does not mean we will have to peer wistfully at it from our distant vantage point. There are several probes being sent to visit the comet at closer range. The missions are sponsored by The Soviet Union, Japan, the European Space Agency, and someone else (I think -- don't quote me on this). The United States' own NASA was not able to send a probe, due to lack of development funds (Thank Reagan for that!) The closest approach I recall being stated is ~100,000 miles. Should be pretty exciting -- we should get pictures almost as good as those from craft like Pioneer and Voyager. >5) What does it orbit? Halley's comet, like all comets in our solar system, orbits the sun. All planets in the solar system also orbit the sun. Now most planets orbit the sun roughly in circular orbits -- actually, as Johannes Kepler noted in the 1600's (around then), all planets are actually orbiting the sun in oval-shaped curves called ellipses, with the sun at one focus of the elliptical orbit (If you must know some of the physics involved, This effect is caused by the inverse-square strength of the gravitational force and the conservation of momentum). A focus of an ellipse is off-center, and for the planets is quite close to the middle of the ellipse. For a comet, however, the sun's focus is near the edge of the ellipse. The above means that the comet is only close to the sun for a short period of time. This is why the planets (in almost circular orbits) are visible and fairly nearby just about all of the time, and comets are so rare. Most of the time, Halley's comet is off in the toodly-bushes of the solar system, at the distance of the planet Uranus -- only once every 75-80 years does it come falling into the solar system, careening past the sun and inner planets, and then wandering off into the nether reaches of space again. >6) How was it created? Scientists believe that comets were formed at the same time as the other planets in the solar system were formed. No comets formed close to the sun, because the heat of the young star vaporized and drove away all the ices and gases close to the star. This is probably why the inner four planets (Mercury, Venus, Earth, and Mars), are so rocky and dense, while all of the significant outer planets (Jupiter, Saturn, Uranus, and Neptune) are gaseous, light (for their size), cold and have icy moons. Scientists believe that there is a large cloud of small dusty, icy balls that SLOWLY orbit the sun far out past the orbit of the outermost known planet, Pluto. This cloud is called the Oort cloud, after the man who suggested its presence. Now these dusty, icy balls are made of the same thing the nucleus of a comet is. Every once in a while, one of these dusty, icy balls will have an orbit that brings it deep into the heart of the solar system, right near the sun. If you remember the year 1976, Comet Kohoutek was one of these "long-period" comets. As any comet comes zooming close in to the sun, the surface starts to heat up, and ices on the surface start to vaporize and form a halo. As the comet gets nearer and nearer the sun, the ices vaporize faster and faster, and the tiny molecules of gas in the halo start to get blown away from the hot sun by the solar wind. Pretty soon the comet grows a long tail. If the comet comes too close to the sun, it may fragment into bits and pieces, forming a train of small rocky debris which the Earth might pass through. The debris will then fall into the Earth's atmosphere and cause a meteor shower. However, most comets don't come this close to the sun, and merely form nice pretty long tails for the few months they are near to the sun. As the comet leaves the vicinity of the sun, the surface of the nucleus cools, the halo becomes less intense, the tail becomes more ephemeral, and the comet disappears from the night sky. Most of the "long-period" comets go zooming back out into the Oort cloud, not to be heard from for another million years or so. Some of these comets, however, manage to zoom into the solar system near a massive planet like Jupiter or Saturn. These comets pass so close to the big planets that the strong gravity of the planet slows them down and greatly perturbs their orbit, causing them to be "captured" and become residents of the inner solar system, where they will have a short period and can be enjoyed every 50-1000 years or so. The comet may orbit the sun several times, then pass by the big planets again, and drop into an orbit even closer to the sun, where it will visit every 5-100 years. These comets, captured by gravity from the far reaches of the Oort cloud, are called "short-term" comets. Halley's comet is of this type, and in all likelihood it used to be one of the ditant long-term comets a million years ago or so. >7) How hot or cold is it? The nucleus is very, very cold, close to the temperature of absolute zero (-270 C or -450 F). The ices it is composed of could not exist on the sultry surface of our lovely planet Earth, where of all the common cometary ices, only water ice exists (ammonia ices and methane ices form at very cold temperatures). The halo and tail are composed of vapors, which may be cold (from about -150 C or -300 F) or hot (to 1000 C or 1500 F) >8) How bright is it? The comet will be bright enough to be easily seen by the naked eye, if you are lucky enough to have a clear night. You must look at it when it is visible in the night sky, however. Just as the moon is not visible every night at 9:00 pm, there will be nights when the Comet is not visible at 9:00 pm. You may need to get up at 3:00 am to see it. Let this early hour never deter you, for it will be beautiful, and indeed awesome in its beauty. It will be very interesting to see how it changes from night to night. (I am going to try to drive up to the top of a 5000-foot mountain to see it every chance I get!) Later daze, -- ____________________ / / \ James T. Perkins ( _____ ( ) \______/ \____\__/ dadla!jamesp | | orstcs!jamesp | | | | 4635 SW Hillside Drive | | Portland, OR 97221 \_____/ 212 Poling Hall, OSU Corvallis, OR 97331 T h e T u b e s A lot of people I know believe in positive thinking, and so do I. I believe everything positively stinks. -- Lew Col
henry@utzoo.UUCP (Henry Spencer) (09/15/85)
> ... There are several probes being sent to visit the comet > at closer range. The missions are sponsored by The Soviet Union, Japan, the > European Space Agency, and someone else (I think -- don't quote me on this). The exact count is 2 Soviet (with some French participation), 2 Japanese (one of which is an engineering test vehicle with limited sensors), and 1 European (the most sophisticated of the lot). That's it. > The United States' own NASA was not able to send a probe, due to lack of > development funds (Thank Reagan for that!) Actually, I think Carter is equally to blame. These things have long lead times. I don't remember exact dates, though. > The closest approach I recall > being stated is ~100,000 miles. Should be pretty exciting -- we should get > pictures almost as good as those from craft like Pioneer and Voyager. The closest approach for Giotto (the ESA probe) is going to be hundreds, not hundreds of thousands, of miles. The pictures should be spectacular; cross your fingers and pray that Giotto survives long enough! A very close encounter with a comet at about 70 kps is not the safest of maneuvers. -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,linus,decvax}!utzoo!henry
szyld@duke.UUCP (Daniel B. Szyld) (09/16/85)
In today's (Sunday Sept.15) New York Times Magazine there is an article on Halley's including viewing dates, etc. It will be seen from the end of Dec. to mid April. The cover article is called "To the edge of the Universe, the new age of Astronomy" and it was written by John Noble Wilford. It includes a description of NASA's space telescope and several pictures of the Milky Way. Good reading.... -- Daniel B. Szyld, Dept.of Computer Science, Duke University, Durham NC 27706-2591. Phone (919)684-3048. Telex 802829 DUKTELCOM DURM CSNET: szyld@duke UUCP: ...!decvax!duke!szyld ARPA: szyld%duke@csnet-relay or na.szyld@su-score
kotter@muscat.UUCP (Rich Kotter) (09/17/85)
> not hundreds of thousands, of miles. The pictures should be spectacular; > cross your fingers and pray that Giotto survives long enough! A very close > encounter with a comet at about 70 kps is not the safest of maneuvers. > -- Being a bit of a novice at such things, I don't know what kps refers to in this posting. Anyone care to shed some light? -- Rich Kotter DEC Portland Oregon decvax!decwrl!muscat!kotter
dta@cpsc53.UUCP (Doug Anderson) (09/19/85)
> > not hundreds of thousands, of miles. The pictures should be spectacular; > > cross your fingers and pray that Giotto survives long enough! A very close > > encounter with a comet at about 70 kps is not the safest of maneuvers. > > -- > > Being a bit of a novice at such things, I don't know what kps refers to > in this posting. Anyone care to shed some light? > > > -- > > Rich Kotter > DEC Portland Oregon > decvax!decwrl!muscat!kotter How about Kilometers Per Second ^ ^ ^ ^ ^ ^
jkw@lanl.ARPA (09/23/85)
> > not hundreds of thousands, of miles. The pictures should be spectacular; > > cross your fingers and pray that Giotto survives long enough! A very close > > encounter with a comet at about 70 kps is not the safest of maneuvers. > > -- > > Being a bit of a novice at such things, I don't know what kps refers to > in this posting. Anyone care to shed some light? > Kilometers per second. Jay Wooten Los Alamos National Lab ARPA:jkw@lanl.ARPA
cew@ISI-HOBGOBLIN.ARPA (Craig E. Ward) (10/29/85)
The November meeting of OASIS/L5 will feature a presentation about Halley's Comet by Tom McDonough. Mr. McDonough is a lecturer in Engineering at CalTech, SETI coordinator for the Planetary Society and author of the forthcoming book Halley's Comet: A Viewer's Guide. He will discuss the history of the comet and give an overview of how and where to view it during its 1985-86 approach. Time and place: Saturday, November 16, 1985 7:00 p.m. Jet Propulsion Laboratory, Von Karmen Auditorium Pasadena, CA Admission is free and open to the public. General information about OASIS/L5 events may be obtained by calling (213)374-1381.
Slocum@HI-MULTICS.ARPA (02/05/86)
> Halley's [rhymes with "valleys"]
I heard a radio news program that interviewed a descendant of Halley
who said that everyone has got the pronunciation wrong. He said that
it doesn't rhyme with "valley" or "daily", but rhymes with "volley".
Haw-lee. He should know, being a descendant.michaelm@3comvax.UUCP (Michael McNeil) (02/07/86)
In article <860205154812.158427@HI-MULTICS.ARPA> Slocum@HI-MULTICS.ARPA writes: >> Halley's [rhymes with "valleys"] > >I heard a radio news program that interviewed a descendant of Halley >who said that everyone has got the pronunciation wrong. He said that >it doesn't rhyme with "valley" or "daily", but rhymes with "volley". >Haw-lee. He should know, being a descendant. *Science 85* last year mentioned that in Edmund Halley's time people frequently spelled things phonetically and that Halley himself usually spelled his name "Hawley." Thus we know that the descendant of Halley you heard is quite correct, and that Edmund Halley did, in fact, pronounce his name as "Hawley." -- Michael McNeil 3Com Corporation "All disclaimers including this one apply" (415) 960-9367 ..!ucbvax!hplabs!oliveb!3comvax!michaelm If the number of the Fixt Stars were more than finite, the whole superficies of their apparent Sphere [i.e. the sky] would be luminous.* Edmund Halley, 1720, "Of the infinity of the sphere of fix'd stars" and "Of the number, order, and light of the fix'd stars" *By today's reasoning the same temperature as the surface of the average star; this is known today as Olber's paradox, or the paradox of P. L. de Cheseaux (1744) and Henrich Wilhelm Matthias Olbers (1826).
henry@utzoo.UUCP (Henry Spencer) (02/22/86)
> *Science 85* last year mentioned that in Edmund Halley's time > people frequently spelled things phonetically and that Halley > himself usually spelled his name "Hawley." Thus we know that > the descendant of Halley you heard is quite correct, and that > Edmund Halley did, in fact, pronounce his name as "Hawley." The JBIS special issue on Halley's Comet, which has been reviewed as "a better overview than most of the Halley's Comet books", observes that Halley's name was spelled in several different ways even at the time, and that there is no longer any way to be absolutely sure just how it was pronounced. Reports from his descendants carry no special weight, because the pronunciation of ordinary names changes too. I believe JBIS did say that "Hawley" is rather more likely to be correct, though. -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,linus,decvax}!utzoo!henry