--------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F1S00007 Date: 01/22/98 From: MARK KAYE Time: 07:13am \/To: ALL (Read 2 times) Subj: Special SKYLINE Bulletin The following message is from David Dunham. Sky & Telescope welcomes observation reports and images by readers of this event. Contact: Observers Log, Sky & Telescope, P.O. Box 9111, Belmont, MA 02174; observers@skypub.com. ================================================================== Subject: See NEAR during its Earth swingby Thurs. night You might be able to see the Near Earth Asteroid Rendezvous (NEAR) interplanetary spacecraft as it swings by the Earth Thursday night and Friday morning. You can generate your own topocentric ephemeris of NEAR at the "topocentric ephemeris for NEAR flyby" item that is available at the I.A.U. Minor Planet Center's Web site: http://cfa-www.harvard.edu/cfa/ps/mpc.html Topocentric ephemerides for NEAR for 32 locations around the world will also be posted on the following Web sites from which they can be downloaded: http://sd-www.jhuapl.edu/NEAR/ (NEAR site) http://www.sky.net/~robinson/iotandx.htm (IOTA lunar site) http://www.anomalies.com/iota/splash.htm (IOTA asteroidal site) These have an improved format, with the time in hours and minutes, and with the Sun altitude given (with no lines when the Sun is above the horizon), that supersedes the ephemerides distributed to some of you yesterday. In addition, data for January 23rd U.T. are now included, including the closest approach with the sunglint phase for the U.S.A. and after the closest approach for the Southern Hemisphere. Later today, a more detailed "groundtrack" ephemeris (long., lat., and altitude) will be placed on the NEAR Web site covering the Sunglint times (Jan. 23, 6:24 - 6:50 U.T.) at one- minute intervals. The Sunglints, when NEAR will shine briefly about as bright as Capella for many regions of the U.S.A., are described in items on the IOTA and NEAR Web sites; timed observations of them are sought to measure solar panel misalignments. This evening, CNN plans to broadcast a short clip about NEAR's Earth swingby and the Sunglints, including an interview with me. An improved local-time map of the U.S.A. showing the predicted track of the Sunglint is now on the NEAR Web site (although it has a few small errors in the city and timezone locations that we'll try to fix by late this afternoon). Skyviews locating the Sunglint for nine different regions are on the NEAR Web site, with one for Hawaii on the IOTA asteroidal site. There is a chart of Perseus, with north up, showing in more detail the location of NEAR during the Sunglint maneuvers for almost 40 cities; it will help those using large binoculars or telescopes which, however, are not necessary; the glint should be easily visible with the naked eye. Note that the Sunglint maneuvers are performed only by rotating the spacecraft slightly using momentum wheels, powered by the ample electricity available from the solar panels; there are no thrusting maneuvers using the spacecraft's fuel to accomplish these pointings. They are a byproduct of a navigation test of the satellite. Most of the time, NEAR will not be reflecting Sunlight from its solar panels and will then be quite dim; see the geocentric ephemeris below. The list of locations for which topocentric ephemerides have been computed are as follows: Location Latitude E. Longitude AUCKLAND, N.Z. -36.908 174.777 TOKYO, Japan 35.6605 139.7702 BRISBANE, Queens. -27.516 153.070 MELBOURNE, Vict. -37.75 145.0 NANKING, China 32.0666 118.8210 PERTH, W. Austrl. -31.95 115.83 NAINI TAL, India 29.3608 79.4567 KODAIKANAL, India 10.2306 77.4686 MOSCOW, Russia 55.755 37.570 MITZPE RAMON,Isrl. 30.597 34.763 CAPE, S. Africa -33.933 18.475 TIRGO Obs., Switz. 45.98447 7.79167 HERSTMONCEUX, UK 50.871 0.338 SAN FERNANDO, Spn. 36.462 -6.200 LA PALMA, CanaryIs 28.75833 -17.8800 RIO DE JANEIRO,Br. -22.8975 -43.18625 ST. JOHN'S, Nfld. 47.537 -52.753 CARACAS, Venezuela 10.5068 -66.928 SANTIAGO, Chile -33.41833 -70.630 Boston, MA 42.3567 -71.0569 Chelmsford, MA 42.62 -71.39 Charlotte Hall, MD 38.51 -76.76 Miami FL 25.77667 -80.19167 near Chicago, IL 42.317 -88.00 Houston, Texas 29.6049 -95.1086 Coal Creek Can.,CO 39.877 -105.391 Mt. Hopkins, Ariz. 31.5647 -110.8846 Casa Grande, Ariz. 32.9583 -111.6542 Los Angeles CA 34.05500 -118.24167 Seattle WA 47.60833 -122.33667 ANCHORAGE, Alaska 61.21 -149.87 Honolulu HI 21.30667 -157.86000 --- Maximus 2.02 * Origin: http://www3.sympatico.ca/mark.kaye/ (1:249/109.1) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F1S00008 Date: 01/22/98 From: MARK KAYE Time: 07:13am \/To: ALL (Read 2 times) Subj: Special Skyline Bulletin (2) An abbreviated geocentric ephemeris of NEAR is given below. The magnitude could be wrong by a few units; we hope to receive some observations soon so that it might be calibrated and updated. A more detailed version of the geocentric ephemeris is on the IOTA lunar Web site. Due to the relatively unfavorable phase angle after the closest approach (which occurs on 1998 Jan. 23, 7:23 U.T. over the Middle East, in daylight), NEAR will likely be much fainter than during its approach. Also, after the swingby, you can see from the table below that NEAR will be visible only from southern-hemisphere observatories. Geocentric ephemeris for NEAR from JPL ephemeris file p_tcm11_n0a generated 1998 Jan. 19 Calendar Solar J2000 min.topo. Date UTC Elong. R.A. Dec. Distance NEAR Year Mo Day h m deg. deg. deg. km Mag. 1998 JAN 21 12:00 140.31 81.01973 21.19753 1097657 17.3 1998 JAN 22 0:00 139.74 80.92815 21.42858 798920 16.7 1998 JAN 22 12:00 139.10 80.73434 21.93338 499065 15.6 1998 JAN 22 18:00 138.69 80.51496 22.50639 348217 14.9 1998 JAN 22 20:00 138.52 80.39282 22.82385 297669 14.5 1998 JAN 23 0:00 138.02 79.96055 23.93556 195848 13.6 1998 JAN 23 2:00 137.59 79.51691 25.05603 144317 12.9 1998 JAN 23 3:00 137.24 79.15099 25.96415 118277 12.5 1998 JAN 23 4:00 136.70 78.57920 27.35372 91951 12.0 1998 JAN 23 5:00 135.71 77.54841 29.76695 65184 11.2 1998 JAN 23 5:30 134.80 76.63340 31.80984 51545 10.7 1998 JAN 23 6:00 133.20 75.05630 35.11400 37647 10.0 1998 JAN 23 6:10 132.35 74.23407 36.73016 32938 9.8 1998 JAN 23 6:20 131.22 73.13511 38.78023 28182 9.4 1998 JAN 23 6:30 129.65 71.58201 41.47221 23373 9.0 1998 JAN 23 6:40 127.33 69.19788 45.17163 18509 8.5 1998 JAN 23 6:50 123.60 65.01014 50.57217 13597 7.9 1998 JAN 23 7:00 116.91 55.51731 59.04067 8687 6.9 1998 JAN 23 7:40 46.40 255.52222 -34.21045 5871 6.9 1998 JAN 23 7:50 54.21 247.58190 -47.43933 10697 8.1 1998 JAN 23 8:00 59.34 241.27041 -54.45557 15620 8.8 1998 JAN 23 8:30 67.14 227.87440 -63.41631 30142 10.1 1998 JAN 23 9:00 70.69 219.29026 -66.74216 44221 10.9 1998 JAN 23 10:00 74.10 209.08617 -69.31563 71530 11.9 1998 JAN 23 12:00 76.79 199.60940 -70.80685 124420 13.1 1998 JAN 23 15:00 78.35 193.72607 -71.40726 201865 14.1 1998 JAN 23 18:00 79.11 190.90908 -71.61942 278269 14.8 1998 JAN 24 0:00 79.89 188.16638 -71.78267 429611 15.7 David Dunham, NEAR Mission Design, 1998 Jan. 21, 8h U.T. --- Maximus 2.02 * Origin: http://www3.sympatico.ca/mark.kaye/ (1:249/109.1) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F1S00009 Date: 01/20/98 From: MIKE DUTTERA Time: 02:43am \/To: JIM VAN NULAND (Read 2 times) Subj: Occultations? JVN>>I mean, what's the JVN>>big deal to the everyday observer re 2 celestial bodies crossing each JVN>>other in the sky? I fail to see any particular big deal about it JVN>>personally. JVN> You don't???? Don't you find it remarkable to watch?? Many people do. JVN>It's a rare event; for many of us, that makes it interesting. It's a JVN>piece of science that us amateurs can contribute, as the pros don't have JVN>portable equipment. Well, I didn't see that such would matter to amateurs, but NOW I do! ;-) I was aware of a few things pros could examine like atmospheres and such but didn't see what "Joe-in-his-back-yard" types would find interesting about them. Thanks, (to you and Mr. Pazmino), Mike --- Platinum Xpress/Wildcat! v1.3 * Origin: Seventh Star - York, PA (717)-225-7256 (1:2700/111) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F1S00010 Date: 01/22/98 From: GERALD PEARSON Time: 07:47pm \/To: ARNOLD G. GILL (Read 2 times) Subj: Red shift and energy Hi Arnold, On 09 Jan 98 16:23:22 Arnold G. Gill wrote about Red shift and energy: GP> magnetic field. In fact, you can take any arbitrary mix of GP> electric and magnetic, and find/calculate a new coordinate system GP> where the field looks pure electric, and find/calculate a GP> _different_ new coordinate system where the field looks pure magnetic. AGG> I'm not sure you can do this. It was something we tried out, and AGG> a pure electric field cannot be made to look like a pure magnetic AGG> field, or vice versa. You always are left with a mix. Thanks for the input. I did _not_ do the calculation. Since you did, your observations about the solutions must be right. BTW, could you check & see if a friend of mine once did the following calculation correctly? (Without a lot of hassle, of course. If it's a big mess, then don't bother.) A physics-grad- student friend of mine once told me that, when he was an undergrad and before he took a course in ralativity, he used the Maxwell equations to calculate the _classical_ force between two electrons moving perpendicular to their separation. I'm assuming that he did the calculation using the "laboratory" coordinate system. Anyhow, there is always the (fixed) electrostatic repulsion between the two electrons, but a moving electron is a current so it will generate a magnetic field, which will cause the _other_ moving electron to "want to" bend toward its "brother". This leads to a magnetic attraction between the electrons, which increases with speed. He said that he had an "Aha!!!!" experience when he suddenly noticed that the magnetic attraction exactly cancelled the electrostatic repulsion when the electrons were moving at the speed of light, so the electrons will _never_ move apart! I think this anecdote is kinda neat, but I _would_ like to know whether or not he did the calculation correctly :-) His result in the case of the electrons moving "at the speed of light" of course agrees with the relativistic prediction, in which the infinite mass and infinite time dialation will keep the electrons moving exactly parallel to each other forever (in the laboratory frame). I never did the calculation myself, and I'm just taking his word for how the calculations came out. I wasn't exactly sure how to calculate the magnetic field generated by a single moving point charge, and decided that I wasn't curious enough to justify what might turn out to be a fairly hairy setup and calculation. -- Gerry --- Blue Wave v2.12 * Origin: The Sacred Scribe, 608 827-6755 (1:121/45) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F1S00011 Date: 01/23/98 From: FRANK JONES Time: 11:05am \/To: ARNOLD G. GILL (Read 2 times) Subj: Gravity and Black Holes You've mentioned several times that, at least at a distance, that there is no difference in the effect of gravity arising from a black hole and from a mass of the same magnitude which is not in a black hole. I suppose that this has been verified by observation? Is there any explanation regarding the differences in the propagation of light and gravity to explain why light cannot leave the black hole but that gravitational influence can? Is the explanation so simple that the deformation of space-time induced by the dense mass is itself "gravity" and that the resulting deformation can be propagated but EM radiation just cannot climb the barrier thus formed? Has this difference perhaps been used in attempts evolve an unified theory including the other forces and gravity? The Michleson-Morley results led to relativity, and general relativity was based on the identity of acceleration and gravity. Perhaps the disparity between the behavior of light and gravity emanating from a black hole and its logical consequences could lead in the direction of an unified theory, maybe by regarding the other forces as being superimposed on the mass-deformed space-time. Being a chemist, I'm way out of my depth here, so apologize for being simplistic....I'm still curious though. FrankO --- PPoint 2.02 * Origin: Frank's Point * Tulsa OK * (1:170/302.5) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F1T00000 Date: 01/23/98 From: JOE CAMBALA Time: 03:50pm \/To: FRANK SHEPLEY (Read 2 times) Subj: Computer program Hello Frank. At the astronomy club meeting, you mentioned an astronomy program, but I forget which magazine it was. Can you tell me the name of the astronomy program, and whether it was Sky and Tel or Astronomy? Also, what page was it on, and and address or 1-800 number, if any that I can call to get more info on it. Good to be back here. Regards to all. --- Platinum Xpress/Wildcat! v1.3 * Origin: Ganas"Family"Fever BBS *(941)728-2132* Alva,Fl (1:371/61) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F1T00001 Date: 01/22/98 From: ARNOLD G. GILL Time: 11:38am \/To: ALL (Read 2 times) Subj: Physics News Updates #355 Hello Y'All! PHYSICS NEWS UPDATE The American Institute of Physics Bulletin of Physics News Number 355 January 20, 1998 by Phillip F. Schewe and Ben Stein THE UNIVERSE WILL EXPAND FOREVER. This prediction is based on new studies of distant supernovas. Because Type Ia supernovas (supernovas in which material falling onto a white dwarf from a companion object ignites violently) brighten and fade in such a predictable way, their intrinsic brightness (and their distances from Earth) can be determined by carefully watching light emission over time. Combining these distances with the velocities of the host galaxies (determined from redshifts) allows one to calculate the expansion of the universe with some confidence. And the result appears to suggest that the universe does not have enough matter (visible or dark) to halt the current expansion. This view emerged two weeks ago at the meeting of the American Astronomical Society in Washington, where optical data for many new supernovas (including the most distant supernova ever observed, one with a redshift of 0.97) were reported by a group from LBL (led by Saul Perlmutter) and one from Harvard-Smithsonian (Peter Garnavich). The new findings are consistent with an age estimate for the universe of 15 billion years. Arnold G. Gill - astrophysician at play --- GoldED 2.41 * Origin: Got a sick star? Call the Astrophysician! (FidoNet 1:153/6.5) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F1T00002 Date: 01/23/98 From: SID LEE Time: 04:22pm \/To: FRANK JONES (Read 2 times) Subj: Gravity and Black Holes -=> Quoting Frank Jones to Arnold G. Gill <=- FJ> there is no difference in the effect of gravity arising from a black FJ> hole and from a mass of the same magnitude which is not in a black FJ> hole. That is correct ;-) FJ> I suppose that this has been verified by observation? We have never "trapped" a BH in a lab and verified it so in that sense I guess the answer is no. However if gravity from a BH were somehow "different" from "normal gravity" then it would completely upset the apple cart for observations of various stellar phenomema we observe and also go directly against many well established and massively tested physics theories such as general relativity so in that broader but admittedly less direct sense it has been tested very thoroughly indeed ;-) FJ> hole but that gravitational influence can? Is the explanation so FJ> simple that the deformation of space-time induced by the dense mass is FJ> itself "gravity" and that the resulting deformation can be propagated FJ> but EM radiation just cannot climb the barrier thus formed? That is it in a nutshell. Mass deforms space and the consequence of that is experienced by us living within the space as what we call gravity. So gravity doesn't "emanate" from a mass, rather gravity is a distortion imposed on space by the existence of mass. However I sense from your question about EM that you may be misunderstanding why a BH is indeed "black". It isn't some mysterious property of a BH that causes EM to be unable to climb the barrier. Rather it is simple physics in action. For any mass there exists a speed which an object (be it photon, space vehicle or golf ball) must exceed in order to escape from the gravitational pull of the mass. This required velocity is called te "escape velocity" and depends on the mass of the object being escaped from and the starting distance the escaping object is from the centre of mass. For the Earth as an example the escape velocity is about 11.2 km/sec. If you want your "golf ball" to leave the Earth you must get it moving at a bit more than 11 km/sec ;-) The formula to calculate escape velocity is simply: v(esc) = SQRT(2 x G x M/R) where SQRT means take the square root of what is inside the brackets, G is the universal constant of gravitation = 6.67 x 10^-11 Nm^2/kg^2 R is the distance from the centre of mass in metres (to keep the units right) M is the mass of the body being escaped from in kg. and V(esc) is the escape velocity in units of metres/sec. A BH results when you manage to "cram" sufficient mass (M) inside a small enough volume (R) the resulting v(esc) at a distance R or less away from the centre of this object becomes greater than the speed of light (300,000 km/sec. more or less). The distance R at which this occurs for any mass is called the "event horizon". Since relativity says nothing can go faster than the speed of light and since EM travels at the speed of light EM and everything else is prohibited from escaping a BH. The EM travels at the speed of light just as an Earth satellite travels at about 10 km/sec in low Earth orbit. but since the escape velocity inside the event horizon is greater than that speed it simply never gets out. We may percieve that as "weird" but that is only because our daily experience is all obtained on Earth where gravity gradients are much less severe and light goes pretty much "where it wants" without any appreciable effect on it and because light moves so rapidly that compared to our human velocities it is effectivel "instantaneous". About the only time we get any experience that EM velocity is less than infinite is when we hear tiny delays in phone calls where the transmission paths run through satellites or, less directly, when we hear NASA scientists explain about how a radio signal to the rover on Mars takes "x" minutes to get there. FJ> Has this difference perhaps been used in attempts evolve an unified FJ> theory including the other forces and gravity? The Michleson-Morley FJ> results led to relativity, and general relativity was based on the FJ> identity of acceleration and gravity. Perhaps the disparity between Of course it has but as yet we are still unable to state what is referred to as a "GUT" or "Grand Unified field Theory" though experts in the field (of whom I am not one ;-) are of the opinion we are making steady progress towards such a unification. -- Regards -- Sid Lee (FIDO - 1:134/122, Internet - sidlee@agt.net) --- Blue Wave/Max v2.12 * Origin: RASCAL BBS [Calgary, Alberta - (403)686-2550] (1:134/122) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F1T00003 Date: 01/24/98 From: MIKE ROSS Time: 12:57am \/To: FRANK JONES (Read 2 times) Subj: Re: Gravity and Black Holes Frank Jones said the following to Arnold G. Gill on the subject of Gravity and Black Holes (23 Jan 98 11:05:08) FJ> Is there any explanation regarding the differences in the propagation FJ> of light and gravity to explain why light cannot leave the black FJ> hole but that gravitational influence can? The reason light doesn't escape a BH so readily is that its photons are infinitely red-shifted to zero energy. A gravitational field on the other hand has only a tiny influence on gravitons. Thus gravity can much more readily escape a BH than light. --- Blue Wave/DOS v2.30 * Origin: Juxtaposition BBS. Lasalle, Quebec, Canada (1:167/133) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F1U00000 Date: 01/23/98 From: NATHAN BOLLINGER Time: 08:53am \/To: HERB GOODMAN (Read 2 times) Subj: Re: Occultations? >>To each their own. If you don't see what the big deal is about ccultations >>don't bother staying up to watch them. :-) But for a lot of folks, atching >>one celestial object cover up another is quite a sight. It sorta lets you >>know that the universe isn't a motionless object. >> >>Transits are neat, too. Like watch what a eclipse looks like from outer >>space. > >They can add a new perspective to observing, thats for sure. I liked >watching Saturn dip behind the moon. Wonder when venus will transit >the sun again? Hmmm, never thought about Venus transitting the sun, but now that you mentions it, that WOULD be something to see! --- SLMAIL v5.02 (#0226) * Origin: The Big Byte BBS 704-279-2295 (1:379/301)