Hamilton Amateur Astronomers Summer 1997 Volume 4 Issue 9 Eugene Shoemaker he world has lost one of its strike Jupiter 16 months later. Comet forward his whole professional life most renowned scientists Shoemaker-Levy 9 was just one of the would be directed toward becoming one with the death of Eugene finds that made this husband-wife team of them. But a medical condition Shoemaker at age 69. On the afternoon the leading comet discoverers of this prevented him from ever being selected of July 18th, Gene and his wife, century. They are also credited with for the Apollo program. "Not going to Carolyn, were involved in a car discovering more than 800 asteroids. the Moon and banging on it with my accident in central Australia. He was But the one research interest he never own hammer has been the biggest fatally injured; Carolyn suffered broken tired of was Meteor Crater, the disappointment in life," he said last ribs but is expected to recover. The kilometer-wide pit east of Flagstaff, year. "But then, I probably wouldn't pair had arrived in Australia just six Arizona. have gone to Palomar Observatory to days before to study some of the take some 25,000 films of the night sky continent's numerous impact craters -- While still in his teens, Gene with Carolyn -- she scanned them all -- an annual trek Down Under that they'd realized that someday astronauts would and we wouldn't have had the thrills of made a habit in recent years. walk on the Moon, and from that point finding those things that go bump in the Ann's Excellent Observing Table ver since I built my 12.5" been laying my charts and things on the telescope, I've been looking van's floor and working from there. But for a small table to hold my stooping over to read charts on the van's star charts and other essential floor causes too much back strain. I astronomy bits and pieces. needed a table! It's not that the larger telescope I decided that the perfect table requires any more charts or accessories, would have: it's just that my old telescope ( an 8" reflector) fit into the hatchback of our - three legs to prevent it from rocking Daytona. The car's long hood on uneven ground Best known for his pioneering functioned very nicely as an observing - adjustable legs to allow the table top work in elucidating the mechanics of table. I would throw a towel on it to to be kept level regardless of how impacts and in the discovery of Earth- protect the paint and to keep things uneven the ground was crossing bodies, Gene gained from sliding around and "voila" I would - to be high enough so I wouldn't have worldwide fame in March 1993 for his have a table. The new 'scope won't fit in to stoop over it discovery, with Carolyn and colleague the car and must be carried in our - to be light, small and easily stored in David Levy, of a comet that would minivan. Unfortunately, the van's hood the van. is too small to be used as a table, so I've (Continued on page 3) Rob'serving Report page 2 SEDS - Canada page 6 inside... "UFO Scope" page 4 Double Stars page 7 Orbiting Gourmet page 5 Ask the "Expert" page 8 Astrologic Puzzle Answers page 5 NEAR page 8 Page 2 Editorial hope everyone has been out thumping." observing this summer because we have finally had He has since expanded his some excellent skies and lots of great article but I was unable to include the star parties. changes due to time and space limitations. I recommend taking the vent Horizon is a publication On page 4 is an article entitled time to explore all of his science pages of the Hamilton Amateur "UFO Scope" which describes a really at: Astronomers (HAA). interesting project. When I contacted http://www.eskimo.com/~billb/ Bill Beaty to get his permission to print The HAA is an amateur his article he had the following I have recently had an astronomy club dedicated to the additional comments: interesting time observing NGC6888, promotion and enjoyment of astronomy "I've been hoping that some amateur the Crescent Nebula. This object is for people of all ages and experience astro people would build a high-gain located in Cygnus and requires a filter levels version and check out various sources. like an O III plus as much aperture as A friend said that comets sound like possible. This is the object that forms The cost of the subscription is rushing wind, and that aurorae make the background for page one of the included in the $15 individual or $20 some sort of noise. My version can't newsletter. I only hope that it survives family membership fee for the year. pick up star twinkle, but I suspect that it the photocopying process. Event Horizon is published a minimum might have interesting sounds, since of 10 times a year. starlight is coherent, and if it forms Stewart Attlesey interference fringes. Motion of the attlesey@interlog.com HAA Council fringes across a small scope aperture Chair Doug Welch might cause more than just rumbles and Second Chair Grant Dixon Honorary Chair Jim Winger Secretary Patricia Baetsen Treasurer Barbara Wight ob'serving Education Dir. Grant Dixon Obs. Dir Rob Roy eport Editor Stewart Attlesey Jupiter's Satellite Shadow Transits !!! Double transit visible Aug. 24 04:18 Recorder Tracy Webb to dawn !!! Membership Dir Ann Tekatch The first time is the start of the Aug. 25 Io 02:22 ---> 04:40 HAJA Coord Rosa Assalone shadow crossing (ingress) and the Aug. 26 Io 20:51 ---> 23:09 second is the end (egress). Because of Sep. 2 Io 22:46 ---> 01:04 Sep. 3 Councillors the large number of shadow crossings Sep. 3 Europa 20:10 ---> 23:01 Alan Shinn for a two month period, I have included Sep. 4 Io 21:11 ---> 01:01 Sep. 5 Bill Tekatch only those that begin and end during Sep. 10 Io 00:42 ---> 03:00 viewing hours and the double shadow Sep. 10 Europa 22:45 ---> 01:36 Sep. Web Site transits. All times are Eastern Daylight 11 http://amateurastronomy.org/ Savings. There are two double shadow Sep. 17 Io 02:37 ---> 04:55 transits in August and one in Sep. 18 Europa 01:21 ---> 04:11 September. Sep. 18 Io 21:06 ---> 23:24 Sep. 21 Callisto *---> 20:13 Aug. 9 Europa 23:08 ---> 02:00 Aug. Sep. 21 Ganymede *---> 22:25 10 Double transit visible from dusk to Aug. 10 Io 22:32 ---> 00:50 Aug. 10 20:13 Aug. 16 Ganymede 22:40 ---> 02:19 Sep. 25 Io 23:02 ---> 01:19 Sep. 26 Aug. 17 Sep. 28 Ganymede 22:48 ---> 02:26 Aug. 17 Europa 01:43 ---> 04:34 Sep. 29 !!! Double transit visible Aug. 17 01:43 ---> 02:19 !!! For other events, such as Aug. 24 Ganymede 02:41 --->* eclipses, occultations, transits of Aug. 24 Callisto 04:18 --->* satellites and the remainder of the shadow transits, search the table in the Event Horizon - Hamilton Amateur Astronomers Page 3 Ann's Excellent Observing Table ... (Continued from page 1) eyepieces from rolling off, it wasn't Ann Tekatch very good. I have since drilled two The table's top could be made from 1.25" holes in the tabletop. Extra easily available thin plywood but the eyepieces sit very securely in these table's legs proved to be a real holes. I've also sealed the plywood and challenge.I checked the local hardware covered it with some self-adhesive stores and couldn't find anything vinyl to keep the wood from getting wet suitable. I was resigned to the fact that I and warping. The plywood could have would have to design some kind of been painted, but the vinyl covering has tripod to set the tabletop on. That's a very cute astronomy theme to it - I when the light bulb above my head couldn't resist. came on! A TRIPOD!!!! M y E x c e l l e n t I l l u m i n a t e d This flash of inspiration hit me Clipboard fits very nicely on the table, about a half hour before a night of too! observing at Binbrook. I dashed into the basement and found a suitable piece of There you have it - Ann's Excellent 1/4" plywood. After rummaging around Observing Table! Try it, you'll like it... the workbench, I found some 1/4 - 20 T-nuts (it's amazing the stuff that astrophotographers have in their basements, eh?). I quickly drilled a hole in the centre of my plywood "tabletop", Rob'serving Report ... hammered in the T-nut and - presto! - instant observing table! (Continued from page 2) * 21- Double shadow transit on I tested the strength of my new "RASC Handbook". In August check Jupiter. table by attaching the plywood top to between 01:00-09:00 UT. At the * 22- Aldebaran 0.3 deg. south of the tripod and then setting Uranometria beginning of September between 00:00- Moon. off to one side of the table - no 08:00 UT and near the end between * 22@1956EDT- Vernal Equinox. problem, the tripod's screw held the 00:00-10:00 UT. Jupiter is rising about tabletop securely enough to prevent the 1 hour earlier every two weeks. To get whole thing from toppling over. your local EDT subtract 4 hours from However, if I wanted to tilt the tabletop the UT shown for each event. * Mercury moves into pre-dawn sky- to hold Uranometria at a convenient best views in 3rd. week of Sept. viewing angle, the book kept sliding Monthly In-Sights * Venus is low in the evening off. I dashed back into the bas ement! twilight and sets about 1 hour after August sunset.. A strip of 1/2" x 1/2" wood * 11/12- Perseid meteor shower * Mars is in the SW in the evening attached along the bottom edge solved peaks. and sets 2 hr. after dusk. Very the problem! * 17- Double shadow transit on small angular diam. Jupiter. (see above) * Jupiter rises near sunset and is The entire "table" took me less than * 21@10pm- Moon passes just 0.008 visible predawn twilight. 15 minutes to put together. Its height is deg. south of Saturn. * Saturn rises early/mid evening. completely adjustable and the three legs * 24- Double shadow transit on * Neptune & Uranus are near the keep the tabletop steady on uneven Jupiter. (see above) Sagittarius/Capricorn border. ground. It's absolutely perfect! And * 25-Moon passes 0.3 deg. north of cheap, too! (If you already have a heavy Aldebaran. Rob Roy duty tripod.) Observing Director September royrg@mcmail.cis.mcmaster.ca After field-testing my table, I've * 1@8pm- Partial Solar Eclipse. added a few more niceties. While * 16:morning- Mercury at greatest observing, I found the table very handy western elongation, 18 deg. for holding eyepieces. Although the lip * 18- The Moon is 0.2 deg North of along the bottom sort of kept the Saturn Event Horizon - Hamilton Amateur Astronomers Page 4 "UFO Scope" FO SCOPE Aircraft strobes are easy to detect as a *sounds* like the low rush of a burning (c)1996 William Beaty loud clicking. Other aircraft lights candle. If the nucleus of a comet has *may* have a standard 800Hz wailing gas jets, occasional explosions, - Binoculars modulation (from their 400Hz vibrating plasma, etc., perhaps some of - Small solar cell supplies), but the thermal inertia of the comet's reflected light will become - Audio amp their filaments tends to filter out any modulated, and the original sound could - Headphones high frequencies. Maybe with a low be extracted by the photodetector. Something I always wondered noise detector the 800Hz of aircraft about regarding UFO sightings. Say lights could be sensed. So far I've not encountered any it's night, and you see a light in the mysterious lights. I have found that my distant sky. Is it really an airplane? Or I put together a better viewer single opamp stage doesn't give enough suppose it is behaving oddly, recently. Binoculars provide a gain to "hear" the dimmest light performing maneuvers impossible for "sighting scope" even when one sources without burying them in noise, an aircraft, etc. Is the light coming eyepiece is occupied by a photocell. A so it's time to modify the thing. Bigger from that object similar to that of a Seimens BPW34 PIN photodiode and gain resistor, a few tens of picofarads lightbulb? Specifically, is the light opamp front end gives a bit more gain across it to prevent oscillation, etc. amplitude of that object pure and than my selenium cell. Headphones smooth DC? After all, nearly all give much better low frequency manmade light sources are modulated response than a speaker. And the whole as a result of their AC power supplies, thing can be battery powered and duct- so their brightness is vibrating with taped to a set of large-aperture audio frequency. Connect a solar cell nighttime binoculars. Any light source to an audio amplifier, hold it under an appearing in the field of view of one incandescent bulb, and you'll hear side will be heard as optically MMMMMMMMMM at 120Hz. So, demodulated audio picked up by the he next HAJA meeting will what sort of vibration might be imposed other. be on Monday, September on those distant lights in the sky, hmm? 15th, 1997 at 7pm in the Burke Science Building, room B148. As a kid with an electronics We will not be meeting in August due hobby I once taped a selenium solar cell to summer vacations. to the eyepiece of a small 50X The Hamilton Amateur Junior telescope, routed it to an audio amp, Astronomers (HAJA) is a group for then pointed it at distant light sources at children aged 12 and under. The night while listening to the signal. meetings generally consist of a brief Incandescent streetlights give a deep discussion about a current astronomy hum, their AC light output is a pure topic, followed by a fun activity. In the 120Hz sine wave. Mercury and sodium If you build this "UFO Scope", last year we have talked about many vapor bulbs are nonlinear, they give a definitely make it a point to use it quite interesting topics. The HAJA home complex 120Hz waveform that sounds a bit before going hunting for "craft." page lists some of the topics with links like WHAANNNNNNNNN. Neon You want to become familiar with the to related sites. You can visit our home signs sound different, with a squealy sounds of all conventional light sources, page at: high frequency buzz component to their including lamps, headlights, aircraft, 120Hz fundamental. Automobile fires, and if you manage to crank the http://www.science.mcmaster.ca/ headlights are DC, so I never tried gain high enough, the twinkle patterns HAA/HAJA/Haja.html viewing them. Recently I saw an article of various stars. That way you'll be by (I think) Don Lancaster which able to point the device at the local In September we would like to mentioned that headlights are version of "Marfa Lights" and either plan some additional activities for the modulated by car vibrations, so I say "yeah, sure, it's just headlights," or children. We could go on a group field checked it out and yes, car headlights possibly "holy ----, aliens modulate trip to the Toronto Science Centre one give off a continuous soft gonging their ship lights for voice comm!" Saturday, or perhaps to a park for a sound even on smooth highways. Their picnic and some solar observing. filaments vibrate, and different cars If a similar device is attached give to the eyepiece of a large telescope, will Rosa Assalone different pitches of "bell" sounds. any interesting sounds be received? For 540-8793 example, the flame of a candle assalor@muss.cis.mcmaster.ca Event Horizon - Hamilton Amateur Astronomers Page 5 The Orbiting Gourmet (Part 2): Soup's On! ne of the neat things about and a gas in the second. There's also a Method: astronomy is that once you change in mixing length - the typical learn about how something distance that a heated cell rises. For Prepare the dashi according to package works, you can spot the same processes your soup, the mixing length is no directions. Cut the green onions into in lots of of seemingly unrelated things. larger than the depth of your bowl, tiny rings. Take the Sun, for example. Bet you while in the Sun, it's millions of times never thought of it as analogous to a larger. Stir the mis o paste into a small amount bowl of soup! But the two are more of the soup stock to soften it up. Pour alike than you might at first realize. Despite the differences, miso soup, this back into the soup pot and stir, illustrates a process that happens adding the green onions and soy sauce throughout the universe. The outer to taste. Bring to a brief boil. Don't let "Despite the differences, fourth of the Sun is churning in this the mixture boil for longer than a few miso soup, illustrates a way, as is the Earth's atmosphere. Pre- seconds, or the miso will lose its flavor. main sequence stars don't just have a process that happens convective region, they're fully If you like, cut up a package of firm throughout the universe." convective. The is phenomenon even tofu and add the cubes at the same time crops up in pulsating variable stars, as the onions. where it serves to dampen the radial The missing link is a process oscillations. * Look in the ethnic foods section of called convection. Both the Sun and the your local grocery store for these items. soup want to be the same temperature as So ladle out a bowl of miso soup. It'll If you can't find them, visit any Asian their surroundings, so they get rid of not only fill your stomach. When you grocery store. One such place is Yum- excess heat by stirring themselves up. contemplate how the swirling broth Yum's on the corner of Locke and King In the Sun, bubbles of hot gas rise to the relates to the rest of the rest of the in Hamilton. surface, where they can radiate their universe, it'll also fill your mind. energy to space. Then the cooled cells If instant dashi is unavailable, you can sink back down, only to be heated up Convecting Miso Soup (serves 4) make the stock yourself using 30 g each again in the Sun¹s interior. of dried anchovies and kelp to 3 cups of 3 1/2 cups instant dashi (fish soup water. Boil until the mixture is reduced These bubbles of gas rising to stock)* to 2/3 of the original volume. Sol's outer surface give it a granular 2 -3 tbsp miso paste* appearance. Each bubble is an 1 package firm tofu (optional) Denise Kaisler enormous 700 km across - slightly more 3 green onions kaisler@soback.kornet.nm.kr than the distance from Hamilton to soy sauce Montréal - yet exists for only about 10 minutes. It's a fascinating show, but limited only to those with meter-class telescopes. Astrologic Puzzle Answer However, you can observe ill was observing M13 and Zelda Zorkovich. Congratulations, ZZ! convection in your very own kitchen by Rosa had the 3-inch Now that you know the whole story, fixing yourself a tasty bowl of miso refractor. there's not much point in my writing soup. Miso is the Japanese word for about this star party for Event Horizon. fermented soy bean paste, a savory From L to R, Bill, Ann, Doug, additive that's low-calorie and rich in Rosa and Stewart, using 10, 6, 8, 3, and NOTE: I intended in #4. that: protein. Just whip up a batch using the 4-inch scopes respectively which were IMMEDIATELY to the left of the following recipe and serve hot. You'll white, gray, pink, black and green in green scope was the black one. If you be able to see the delicate grains of colour. They observed M13, the assumed that it could be anywhere to miso billowing up from the bottom in double-double, M57, Albireo and a- the left, there are other solutions. graceful clouds. Herculi using Norton's, Mag-6, Apologies for the oversight. Cambridge, Uranometria and Sky Atlas Realise of course, that temperature isn't 2000. Rob Roy the only difference between your soup royrg@mcmail.cis.mcmaster.ca and the Sun. The medium for Thanks to the thousands who convection is a liquid in the first case submitted answers and helped solve this puzzle. Complete set of Naglers went to Event Horizon - Hamilton Amateur Astronomers Page 6 SEDS-Canada would like to inform you of graphics, animation, video, and sound. * Java applets and/or JavaScript the second annual SEDS- Scholarships and prizes with a value up interactive virtual environments (in Canada multimedia contest on to $500 will be awarded to the best VRML) the world wide web. SEDS-Canada is a essays. national educational organization The multimedia essays may be dedicated to encouraging students to Inspiration SEDS-Canada created in English and/or French. pursue studies in science and invites the students across Canada to All multimedia essays should engineering by generating interest in produce and submit an original, self- include a cover HTML page with the space exploration. contained multimedia essay about space exploration for ready use on the World student's full name, grade/year, school There are three essay topics Wide Web. The actual space or institution, and address (including which are categorized according to the exploration topic depends on the email address if any). The cover page academic levels of the SEDS writer's age group (kindergarten to should also include a very short membership. A total of $1,200 in prize grade 8, junior/senior high school, introduction of the student, describing money will be awarded to the best college/university). how and why s/he got interested in entries. Contest guidelines are posted at space exploration. Group entries are http://www.seds.ca/Contest/. As well, a Eligibility Those eligible are only allowed for the K-Grade 8 level short description of the topics is all Canadian students from kindergarten category. All other entries must be enclosed. I would appreciate your to grade 13, CEGEP, and University or individual. assistance in distributing the contest College undergraduates. All entrants All entries must be viewable flyers to your members. must currently be studying in a Canadian secondary or post-secondary on a standalone multimedia computer If you have any questions educational institution. Entrants must using Netscape Navigator 3.0 or regarding the contest, do not hesitate to address the essay topic designated for Microsoft Internet Explorer 3.0. contact me. My phone number at work their grade level. Contest entries are due on is 978-4560 and my e-mail address is: October 1 7, 1997 and can be mailed to: christine.marton@utoronto.ca. I look Awards The student with best SEDS-Canada, c/o Christine Marton, forward to receiving many excellent multimedia essay for each level will 125 Hanson St., Toronto, ON, M4C entries from your members. awarded an cash award and his/her entry will be placed online at the 1A3 Yours sincerely, SEDS-Canada WWW site for a year. All entrants will be notified by Christine Marton All finalists will receive a certificate of November 28, 1997, if they have been Treasurer merit. All entrants will receive a free selected as finalists The winners will be June 23, 1997 annual student membership in SEDS- contacted and their prizes will be Canada and subscription to Ylem, the mailed. SEDS-Canada Multimedia Essay SEDS-Canada newsletter. Contest Essay Topics: Imagination All multimedia essays must be original works, but may Diary of a Canadian Astronaut Web site: http://www.seds.ca/Contest include references obtained from online (Kindergarten-Grade 8 Level) email: seds@seds.ca sources or published material (in any media). All references, online or not, First Prize: $100 SEDS-Canada is proud to should be cited (identify the original Canadian astronauts like present its second annual Multimedia author, title, publication/site, URL, and Bjarni Tryggvason are conducting Essay Contest. Space exploration is not date). research that only about astronauts, rockets, and will help design the International Space robot probes It is also about inspiration, General Guidelines Station. Space stations represent one imagination, and insight. The purpose step in humankind's ongoing quest to of this contest is to give students across All multimedia essays must be created explore the solar system and beyond. Canada an opportunity to inject new using HTML and may include: inspiration, imagination, and insight Follow a day in the life of a into the Canadian space program. To * graphics (in .GIF or .JPG format, Canadian astronaut during an actual allow students to express themselves to including animated .GIFs) space shuttle mission (such as Bjarni the fullest, the format of the * video (in Quicktime, RealVideo, or Tryggvason's upcoming flight on STS- competition is a multimedia essay, an MPEG-1 format) 85), and in doing so, answer the HTML document rich with text, * sound (in .AU or .WAV format, or following questions: What does an using RealAudio) astronaut do aboard the shuttle? What Event Horizon - Hamilton Amateur Astronomers Page 7 SEDS-Canada ... sort of work does s/he do? How does s/ inconclusive. he sleep? How does he/s eat? How does s/he have fun? Did going into space Board of Directors Observing change her/his personal outlook of the Li-Te Cheng world? What does Canada look like President Double Stars from space? Memorial University Calvin Li ear Friends in Astronomy: Builders of the Arrow (Junior/Senior Vice President High School Level) University of Waterloo I have just read the First Prize: $200 Christine Marton article "Observing Double Stars" which The most famous plane in Treasurer appeared in the March 1995 (Vol.2, Canadian history is the Avro Arrow University of Toronto Issue 5) issue of EVENT HORIZON, (CF-105) which was rolled out on and thought that you might be Jess Angws October 4, 1957. 1957 also marked the interested in the DOUBLE STAR Secretary dawn of the space age as the then OBSERVER. McMaster University Soviet Union launched Sputnik 1, the first orbital satellite. Two years later, Jim Talbot I have just begun to republish the 50th anniversary of Canadian Membership Director the DOUBLE STAR OBSERVER after aviation saw the Canadian government York University stopping two years ago due to arthritis cancel the Arrow program and destroy Sanjay Singh problems. A new doctor has greatly all Arrow aircraft. Education Director improved this condition, so the University of Waterloo DOUBLE STAR OBSERVER is back. Many highly skilled engineers It is a quarterly newsletter devoted and technicians left Canada to work on Board of Advisors entirely to double star observing, and the fledgling American space program. Fred Christie will soon return to its former worldwide Examine the backgro und of key Vice President distribution. A subscription to the personnel from the Avro Arrow project, Bristol Aerospace DOUBLE STAR OBSERVER is only and discuss in detail their contributions $6.00 U.S. funds outside of the United to the Arrow project, as well as their Lydia Dotto States. This price covers publication contributions to the American and Science Writer costs and mailing. Hopefully, the low Canadian space program. Paul Fjeld price will encourage amateurs to Space Artist subscribe. New Life for Mars (College/ Chris Hadfield University Level) Astronaut, CSA If you are interested in First Prize: $500 David Kendall subscribing, please send a Canadian Viking 1 and 2 were the first Program Scientist, postal money order for $6.00 U.S. spacecraft to land on Mars. Launched in Canadian Space Agency funds, made payable to Ronald C. 1975, their mission was to determine Tanguay. The address is: Rob Stewart whether life had existed on that planet. Planetary Scientist, However, they found no strong DOUBLE STAR OBSERVER University of Calgary evidence for the existence of life on c/o Ronald C. Tanguay Mars, even in a primitive form. Twenty Rod Tennyson 306 Reynolds Drive, years later, 1997 will see the Aerospace Engineer, Saugus, MA 01906-1533, rendezvous of Mars Pathfinder and UTIAS U.S.A. Mars Global Survey at Mars, as well as Bob Thirsk the launch of the Cassini mission to Astronaut, CSA Clear skies & good seeing. Saturn. Gethyn Timothy Space Scientist/Educator, UNB Ronald C. Tanguay Using data from past robotic Massachusetts Institute of Technology missions, including Viking, design both The M.I.T. Libraries the biological experiments, and the Cambridge, MA probe that would deliver them to the planetary surface, that could test for the presence of life. Discuss why Viking tests results may have been Event Horizon - Hamilton Amateur Astronomers Page 8 Ask the "Expert" (Part two) cannot understand how Kepler's formula can be simplified to: astronomers can know how (8.5 KPc x 3.08x1016 Km/KPc x pi x 2) our galaxy looks, or where = m = a3/P2 we are located in it. 220 KM/Sec Brian Chire (8.5 KPc x 2.0628x108 AU/KPc)3 = 7.477x1015 seconds = Yes, this is last month's (237 MYr)2 question again. The first time I tried to = 237 Million Years = 9.6x1010 or 96 billion Suns answer this I ran out of room. To Since the mass of the Sun is refresh your memory, I previously insignificant relative to the Milky Way, (Continued on page 10) explained how Shapley found that globular clusters formed a spherical shell centered somewhere in the direction of Sagittarius at a distance of NEAR: Flying by Mathilde 25,000 to 30,000 light years. And now n June 27 at 8:50 am EST the Density: ~ 1.3 g/cm³ for the rest of the story. asteroid Mathilde finally had Albedo: 3% a visitor. The NEAR 5 craters > 20 km across. In the 1920's Jan Oort and spacecraft passed within 1200 km of the Largest crater 30 km across,6 km Bertil Lindblad measured motions of asteroid and flew by at 10 km/sec. deep. stars in the vicinity of the Sun. They Mathilde is a dark C-type asteroid some No satellites found yet. found that the motions would be best 60km in diameter which rotates once understood if the Sun and surrounding every 17.5 days. The encounter took For more information go the stars were orbiting some distant point. place some 2 au from the Sun and some NEAR web page at It appeared that the Sun is orbiting a 1.7 au from Earth. Due to power http://sd-www.jhuapl.edu/NEAR. more-or-less circular path around a limitations the only working instrument point many thousands of light years was the multicolour camera. Here are Below is a comparison of Ida,Gaspra away. This agreed with Shapley's some of the first findings from the and Mathilde. observations of globular clusters. encounter: Ray Badgerow Recent measurements show Size: ~ 50 X 53 X 57 km 667883@ican.net that the Sun is orbiting the centre of the Volume: 600,000 km³(±30%) Galaxy at a distance of about 8.5 Mass: ~1017g(±6%) KiloParsecs* (KPc) at an orbital speed of about 220 Km/sec. With this information and the assumption that the density of stars in the Sun's vicinity is typical for the whole galaxy it is possible to estimate the mass of the galaxy. This is done using Kepler's law as modified by Newton to include the masses of two bodies in orbit. (m1 + m2) P2 = a3 where: m1 - mass of the Sun m2 - mass of the galaxy P - orbital period in years a - semimajor axis in AU** * 1KPc = 3.08 x 1016 Km ** 1AU = Distance from the Earth to the Sun To calculate the period: P = Orbital circumference/Orbital speed Event Horizon - Hamilton Amateur Astronomers Page 9 August / September Night Skies Event Horizon - Hamilton Amateur Astronomers Page 10 Ask the "Expert" ... (Continued from page 8) spiral structure of the Milky Way. Since the Sun is a larger than average star, the number of stars must From the mass and distribution be a few hundred billion. Note that this of stars we can conclude that the Milky ignores the mass beyond the orbit of the Way is similar to many other spiral Sun including dark matter. galaxies visible in the night sky. A whole book could be written about this So far we know that our subject but I hope that this gives you at galaxy is a disk and has a mass at least least a partial answer. 96 billion times that of our own Sun. Further details about our galaxy are to be found using radio telescopes to Spiral Galaxy M74 in Pices measure the energy given off by hydrogen at a wavelength of 21.1 cm. One advantage of using this wavelength is that it can pass relatively easily Doug's Stuff Fer Sale through obscuring gas and dust in our galaxy as compared to visible (2) 8" blanks 300mm f/4.5 Telephoto, Canon mount wavelengths. When a radio telescope is $65 each $75 pointed in a particular direction in the (3) 6" blanks (400 grit ground 2 sides) Keychains plane of our galaxy the 21.1 cm $45 each $6 each emission is picked up from all locations 6" Pyrex blank + ceramic tool FAX/Phone line-splitter along the line of sight. Due to variations $75 $40 in the rotational speed with distance 4 1/4" Pyrex blank Don't see what you'd like? Ask me! from the centre of the galaxy it is $25 possible to measure the distribution of 4" Optical flat Doug Welch hydrogen. This is because of the $125 (905) 525-9140 x23186 (work) variation of the emission frequency Metal detector (905) 524-0848 (home) from 21.1 cm from Doppler shifting. In $75 welch@physics.mcmaster.ca this way it is possible to map out the Super 8mm Canon camera $50 CALENDAR OF EVENTS Aug 29, 30, September 5, 6, 26, 27 BINBROOK OBSERVING SESSIONS - Proposed observing nights. For confirmation or directions call Rob Roy (692-3245) or Ann Tekatch (575-5433) Tuesday, September 2, 11:59 PM EVENT HORIZON DEADLINE - Please submit your articles and pictures to Stewart Attlesey, attlesey@interlog.com or modem (905)827-9105 or snail mail to 1317 Mapleridge Cres., Oakville, L6M 2G8 Thursday, September 4, 8:00 PM ROYAL ASTRONOMICAL SOCIETY OF CANADA Hamilton Centre - General Meeting - Spectator Building auditorium. September 5,6 &7 HURONIA STAR PARTY - Put on by the South Simcoe Amateur Astronomers. Contact Christopher Trace (905)729-4982 for details. Friday, September 12, 7:30 PM HAA GENERAL MEETING - at the Spectator Building auditorium. Speaker to be announced. Parking lot observing, weather permitting. Monday, September 15th, 7:00PM HAJA MEETING - McMaster Burke Science Building, room B148. See Page 4. Friday, September 19, 7:30 PM COUNCIL MEETING - Location to be announced. Call Doug at 525-9140 Extension 23186 if you are interested in attending. Saturday, September 20, 8:00 PM COSMOLOGY DISCUSSION GROUP - Room B148 (next to the Planetarium) Burke Science Building, McMaster University. Topic will be "Introduction to Cosmo logy". For more information contact Bill Tekatch at 575-5433 or tekatcba@mcmail.cis.mcmaster.ca Event Horizon - Hamilton Amateur Astronomers