--------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F3P00000 Date: 03/19/98 From: ARNOLD G. GILL Time: 11:07am \/To: SPOCK (Read 1 times) Subj: Impact Hello Spock! On 16 Mar 98, Spock wrote to All: S> Hello. I'm writing this lines because I want to know anything about a S> comet or an asteroid who will impact over superface of the earth very S> soon There is none. On another note, I suggest you put your real name in the heading - pseudonyms are strongly discouraged in this echo. Generally speaking, if a person is not willing to put their name to their words, then their words probably don't mean very much. 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: F3P00001 Date: 03/19/98 From: ARNOLD G. GILL Time: 11:14am \/To: BOB KING (Read 1 times) Subj: Asteroid passing close to Earth Hello Bob! On 18 Mar 98, Bob King wrote to Mark Bloss: >> Our moon, for example, used to be part of >> our planet's magma, having been thrown clear of the Earth about 4.5 billion >> years ago due to the impact with our planet with another planetesimal, >> or (very) large asteroid.) BK> Not so, this theory has been discarded a long time ago. BK> Analysis of moon samples show that we don't have a common origin, BK> except that both were formed as part of the solar system. I think you got this mixed up. All current books on astronomy say that the best theory for the Moon's formation is due to a major impact of a Mars-sized body with the Earth. To quote, "its as if the Moon were composed of the same basic silicates as the Earth, with the core metals and the volatiles selectively removed". A major oblique impact would "splash" the mantle of the Earth (and this other body), leaving the metallic core of the Earth undisturbed. Also, the core of the impactor merges with the Earth's. The splashed mantle, in the form of a hot vapour, would be at high temperatures, thus eliminating any of the volatiles in it and leaving only the silicates that are observed on the Moon. 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: F3P00002 Date: 03/18/98 From: MARK KAYE Time: 10:12am \/To: ALL (Read 1 times) Subj: Skyline for 1998-03-13 Sky and Telescope's SKYLINE for 1998-03-13 Although currently no known asteroids are on a collision course with the Earth, there are nevertheless more than 100 bodies worrisome enough for the Minor Planet Centre to catalog them as "potentially hazardous objects." The purpose of this list is to identify asteroids and comets that astronomers should routinely check to refine their orbits. On March 11th, Brian Marsden of the Central Bureau for Astronomical Telegrams announced a new contender. The asteroid, designated 1997 XF11, was discovered by University of Arizona asteroid hunter James Scotti on December 6, 1997, as part of the Spacewatch project. Using additional observations made over the next three months, Marsden calculated a preliminary orbit for the 1.4 to 2.7 km wide rock that showed it would pass only 40,000 kilometres above Earth's surface on October 26, 2028. However, the margin of error was still relatively large, the only near certainty was that 1997 XF11 would pass by us at a distance closer than the Moon. The circumstances of the flyby seemed to continually change during the following day as other astronomers made their own analyses. Orbital calculations by Donald Yeomans and Paul Chodas (Jet Propulsion Laboratory) showed that closest approach would be some 80,000 km, with errors only half as great. Furthermore, the "target plane" of the asteroid did not intersect the Earth and thus the probability of impact was zero. Eleanor Helin (JPL) reports finding a prediscovery image of the object. Incorporating positions from this 1990 observation moved the nominal flyby distance out to a comforting 950,000 km. Additional observations over the next weeks and years will continue to firm up these figures. The Earth already has many visible scars of cosmic collisions. Now researchers have linked five impact features and suggest that they all formed at the same time as a shattered comet or asteroid struck the Earth, much as the pieces of Comet Shoemaker-Levy 9 hit Jupiter in 1994. In the March 12th NATURE, David Rowley (University of Chicago), John Spray (University of New Brunswick) and Simon Kelley (The Open University) explain how after moving the drifting continents back to their arrangement 214 million years ago, impact scars in France, Canada, Ukraine and Minnesota lined up. The largest of the craters is 100 km across. These impacts are a likely influence on the mass extinction of life at the end of the Triassic period, where 80 percent of the species then living on the Earth disappeared. While some astronomers were worrying about very nearby cosmic objects, others announced the most distant. Observations Arjun Dey (Johns Hopkins University) and his colleagues using the 10 metre Keck II telescope atop Hawaii's Mauna Kea picked up the faint light from a galaxy called 0140+326RD1 (RD1 for short). With a redshift of 5.34, the first object to break the 5.0 "barrier" this young galaxy is seen as it was when the universe was only 6 percent of its present age (about 820 million years after the Big Bang). This is nearly 90 million light years further than any previously discovered object. Details of the study will appear in Astrophysical Journal Letters. NASA scientists made a final try to contact Mars Pathfinder on March 10th. The last full transmission from the lander came in on September 27th, but signals were regularly sent to the lander in the faint hope that contact would be restored. Those transmissions ended Tuesday, marking the official end of the mission. That is all for this week. MK --- Maximus 2.02 * Origin: http://www3.sympatico.ca/mark.kaye/ (1:249/109.1) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F3P00003 Date: 03/18/98 From: MARK KAYE Time: 10:13am \/To: ALL (Read 1 times) Subj: This Week At a Glance This Week's "Sky At a Glance" Some daily events in the changing sky, from the editors of SKY & TELESCOPE. MARCH 15 -- SUNDAY Spica is to the right of the bright waning gibbous Moon after they rise in midevening. MARCH 16 -- MONDAY Telescope users in the Far East with good sky conditions can look for Mercury passing barely north of the 6th-magnitude star 60 Piscium around 13:00 Universal Time -- so closely as to just miss occulting it. MARCH 17 -- TUESDAY Look southwest in the evening this week for Orion. As winter gives way to spring Orion moves lower toward the west, and its three-star Belt, diagonal for most of the winter, becomes nearly horizontal. MARCH 18 -- WEDNESDAY The eclipsing variable star Algol is at minimum light, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 8:53 p.m. EST. It takes several additional hours before and after to fade and rebrighten. For a complete schedule of Algol's eclipses, see http://www.skypub.com/whatsup/algol.html. MARCH 19 -- THURSDAY Mercury is at its greatest elongation in the west at dusk (19 degrees east of the Sun). MARCH 20 -- FRIDAY The March equinox occurs at 2:55 p.m. Eastern Standard Time. This is when the Sun crosses the equator moving north, marking the start of spring in the Northern Hemisphere and autumn in the Southern Hemisphere. MARCH 21 -- SATURDAY Last-quarter Moon (exact at 2:38 a.m. EST). For tips on viewing our nearest celestial neighbor, see "Touring the Moon with Binoculars" at http://www.skypub.com/whatsup/moontour.html This Week's Planet Roundup MERCURY and SATURN are low in the west as twilight fades. Mercury is the brighter of the two. Early in the week Mercury is to Saturn's lower right. By Thursday or Friday it's more directly to Saturn's right (about 5 degrees from it) and fading. VENUS shines brightly in the southeast during dawn. MARS, quite faint, is disappearing into the sunset below Mercury. JUPITER is hidden in the glare of sunrise. URANUS and NEPTUNE are emerging from the glow of sunrise. They're far in the background of brilliant Venus. PLUTO, magnitude 13.8, is near the Ophiuchus-Scorpius border, well up in the southeast by about 2 a.m. (All descriptions that relate to the horizon or zenith are written for the world's midnorthern latitudes. Descriptions that also depend on longitude are for North America. Eastern Standard Time, EST, equals Universal Time minus 5 hours.) Full details, sky maps, and news of other celestial events appear each month in SKY & TELESCOPE magazine. Clear skies! --- Maximus 2.02 * Origin: http://www3.sympatico.ca/mark.kaye/ (1:249/109.1) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F3P00004 Date: 03/18/98 From: ROBERTO BALDINI Time: 01:55pm \/To: TUTTI (Read 1 times) Subj: This Week At a Glance [ASTRONOMY] ======================================== Messaggio riportato dall'area ASTRONOMY Mandato da Mark Kaye a All soggetto "This Week At a Glance" ======================================== This Week's "Sky At a Glance" Some daily events in the changing sky, from the editors of "SKY & TELESCOPE". FEB. 22 -- SUNDAY Mercury is in superior conjunction, behind the Sun. As dawn begins to brighten on Monday morning, look low in the southeast for Venus just to the left of the waning crescent Moon. FEB. 23 -- MONDAY The eclipsing variable star Algol should be at its minimum brightness, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 10:19 p.m. EST. For a complete schedule of Algol's eclipses for the rest of this observing season, go to http://www.skypub.com/whatsup/algol.html. Jupiter is in conjunction behind the Sun. FEB. 24 -- TUESDAY The red long-period variable stars T Hydrae and V Canum Venaticorum should be at maximum brightness (7th or 8th magnitude) around this date. FEB. 25 -- WEDNESDAY As winter winds down, three carnivorous constellations of early spring climb the eastern evening sky in parallel. In the northeast is Ursa Major, the Great Bear, which includes the Big Dipper. In the east is Leo the Lion. And in the southeast is the head and front half of long, dim Hydra, the Sea Serpent. FEB. 26 -- THURSDAY New Moon, and ECLIPSE OF THE SUN! The eclipse will be total in parts of northern South America and the Caribbean. It's partial for much of the United States and eastern Canada (south and east of a line from Southern California through Kansas, Michigan, Quebec, and Labrador). See the map and other information in the February Sky & Telescope, page 82 (it's also on SKY Online at http://www.skypub.com/eclipses/eclipses.html). The article has tips for viewing the Sun safely and projecting its image for classroom viewing. Algol is at minimum light for a couple hours centered on 7:08 p.m. EST. FEB. 27 -- FRIDAY A hairline waxing crescent Moon is close to dim Mars very low in the west at dusk. Try using binoculars; look far to the lower right of Saturn. This might be your final goodbye to Mars for the year. Saturn's largest moon, Titan, is three or four ring-lengths east of the planet this evening through Monday evening. FEB. 28 -- SATURDAY The crescent Moon shines below Saturn during and after dusk. This Week's Planet Roundup MERCURY, JUPITER, URANUS, and NEPTUNE are hidden in the glare of the Sun. VENUS shines brightly in the southeast during dawn. MARS is disappearing into the sunset. It's very far to the lower right of Saturn. SATURN, in Pisces, shines at magnitude +0.6 in the west-southwest during and after dusk. PLUTO, magnitude 13.8, is at the Ophiuchus-Scorpius border in the south- southeast before dawn. (All descriptions that relate to the horizon or zenith are written for the world's midnorthern latitudes. Descriptions that also depend on longitude are for North America. Eastern Standard Time, EST, equals Universal Time minus 5 hours.) More details, sky maps, and news of other celestial events appear each month in SKY & TELESCOPE, the essential magazine of astronomy. See our incredibly rich Web site at http://www.skypub.com/. Clear skies! SKY & TELESCOPE, P.O. Box 9111, Belmont, MA 02178 * 617-864-7360 (voice) --- IntuiPoint 1.2.6 beta R #18 * Origin: Antares_point (2:332/405.31) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F3P00005 Date: 03/19/98 From: BARTON PAUL LEVENSON Time: 05:33pm \/To: BOB KING (Read 1 times) Subj: Asteroid passing close to Earth BK> Not so, this theory has been discarded a long time ago. BK> Analysis of moon samples show that we don't have a BK> common origin, except that both were formed as part of BK> the solar system. I don't agree. I still like impact-accretion. BK> Not so; A nuclear blast would fragment it and probably BK> compound the problem by making many of the pieces from BK> an uncontrolled explosion collide with the earth. BK> It certainly would not have enough power to vapourise it. If a nuke goes off on the near side I can't see many of the pieces making it Earthward, and even if so they should be small enough to burn up in the atmosphere. More nukes, say I. Wargasm. Oooh. --- Maximus 3.01 * Origin: SoundingBoard, Pittsburgh PA (1:129/26) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F3P00006 Date: 03/19/98 From: ADAM MAJER Time: 10:43pm \/To: MIKE ROSS (Read 1 times) Subj: A 5th force? [1/2] MR>Barton Paul Levenson said the following to Mark Bloss on the subject of MR>A 5th force? [1/2] (15 Mar 98 20:32:20) MR> BPL> If lambda is non-zero there is a fifth force driving it. MR>A new 5th force is an interesting idea. Another is the 2 forms of MR>gravity proposed in a quantum gravity theory. The 1st, mediated by MR>particles called gravitons, is the familiar universal G which attracts MR>large masses over a great distance. MR>The 2nd form, mediated by particles called gravitinos, is repulsive and MR>works only at the subatomic level, thus only over a very small distance. MR>Possibly it is the unforeseen large scale effect of this repulsive form MR>which has been detected? You're right but there could be another explonation. A gravitino emited from a mass A will travel a distance x after which it will decay into a graviton. * SLMR 2.1a * hAS ANYONE SEEN MY cAPSLOCK KEY? --- FMail 0.92 * Origin: The Programmer's Oasis on FIDONET! (1:348/203) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F3P00007 Date: 03/19/98 From: ADAM MAJER Time: 10:43pm \/To: TOM FURIE (Read 1 times) Subj: Asteroid passing close to TF>What does everyone think of this asteroid that'll pass close to the Earth TF>in about thirty years? Am I right in thinking the estimated distance wil e TF>approximately 30,000 miles, with a margin of error of 180,000 miles? Fair TF>enough that's a pretty small probability that the asteroid will actually TF>hit Earth, but if it does, I've heard that it could wipe out as much as /3 TF>of the human population (this might not be such a bad thing actually). If TF>it turns out in the years to come that the asteroid IS on a collision TF>course, what do you think we'll be able to do to maybe divert the TF>trajectory for instance? We don't have to worry about it at this time. Worrying won't help and simply clutters Astronomy and other space echos. If the asteroid is on the collision course with earth then we'll know about it well in advance to react accordingly. (Now, what about all those asteroids that remain undetected?) * SLMR 2.1a * It's only a hobby ... only a hobby ... only a --- FMail 0.92 * Origin: The Programmer's Oasis on FIDONET! (1:348/203) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F3P00008 Date: 03/19/98 From: ADAM MAJER Time: 10:43pm \/To: MARK BLOSS (Read 1 times) Subj: Asteroid passing close to MB> miss the Earth - but if it strikes the moon... worse case scenario: MB> disturbing our Moon's orbit enough either for it to be captured by MB> the Earth's gravity and slam-dunked into our planet, or throwing it MB> clear of Earth's gravity, thus altering irrevokably the eco-geosphere MB> of our planet entirely. Or, it could fragment our moon to such an extent MB> that Earth would form rings, like those of Saturn. The fallout from such Wait a minute. If that would happen, the asteroid would need about .5 the KE of the moon (estimate) or about 1.5*10E22 J!! If the density of the asteroid is 5000kg/m3 (real high-lot's of iron to givve it more juice) and it's dia. is 2km then it's minimum speed would be roughly 9*10E7 m/s or 0.30c!!! Now that's moving FAST! I don't think it would stay in our galactic cluster with this kind of velocity! * SLMR 2.1a * This tagline stolen by Silly Little Mail Reader! --- FMail 0.92 * Origin: The Programmer's Oasis on FIDONET! (1:348/203) --------------- FIDO MESSAGE AREA==> TOPIC: 180 ASTRONOMY Ref: F3P00009 Date: 03/19/98 From: ADAM MAJER Time: 10:43pm \/To: ARNOLD G. GILL (Read 1 times) Subj: Asteroid passing close to AGG> This is so far from reality, that it almost isn't worth commenting on. AGG>1-km asteroid will make about a 200-km wide hole if it strikes the Moon r AGG>Earth. On the Moon, it'll be a wonderful spectacle as seen from the Earth, AGG>the Earth it would nearly wipe out all life. Anything else is a miss hat AGG>most people won't notice. AGG> Exaggeration is just fear-mongering. All life?? I think that's a bit exaggerating. It depends where the asteroid hits. If it hits the ocean, there'll be less demage than if it hit central Asia or NA or other populated area. And I'll have to assume that by all life you meant about 50% of humans and most (80%) of the creates that live _on_ the land and measure over 1m in length. There;s still a lot of hidding places - caves for example - where everyone can hide. PS If the asteroid in on the collision course with Earth there will certainly be some kind of intervension offered. * SLMR 2.1a * --T-A+G-L-I+N-E--+M-E-A+S-U-R+I-N-G+--G-A+U-G-E-- --- FMail 0.92 * Origin: The Programmer's Oasis on FIDONET! (1:348/203)