ASTRONOMY CLUB OF TULSA
OBSERVER
E-mail version
February 1999
http://www.b-its.com/astroclub
ACT, Inc. has been meeting continuously since 1937 and was incorporated in 1986. It consists of 150 members and is a nonprofit, tax deductible organization dedicated to promoting the science of astronomy and the education of the public.
Words of Wisdom:
"Our new candy bar from NutShell Universe is the Milky Way, a nebulous nougat covered with gobs of dark matter and rich in star clusters!"
WHAT:
The Astronomy Club of Tulsa Meeting
WHEN:
Friday February 26, 1999 at 7:30 P.M.
WHERE:
NEW PLACE
: Room M1 inside Keplinger Hall, the Science & Engineering Building at TU. Enter the parking lot on the east side of Keplinger Hall from Harvard onto 5th Street. This will take you directly toward the staircase to enter the building. M1 is the first room on the left.FUTURE MEETINGS:
March 26, April 30, May 28
THIS MONTH'S PROGRAM:
Gary Campbell will be giving a presentation on "CCD Imaging Techniques." Gary has been a doing Astro CCD Imaging for the past five years. He has made some very detailed and beautiful images of galaxies and star clusters. He has been approached by Sky and Telescope Magazine who has considered publishing some of his work in their publication. He is the owner of Alphagraphics in Eaton Square and is a graduate of the University of Denver in Colorado.
LAST MONTH'S PROGRAM:
Thanks to all who shared in the "Show and Tell."
ACT COMMITTEES:
Please read through the following list of committees and consider where you would like to help. If every club member could help serve in some capacity, even for a limited time period, it would help us accomplish so much more. I'll have a sign-up sheet for all the committees at the February meeting so you can get involved. Even if you have told me verbally an area you are interested in, please plan to sign up. If you should miss the February meeting, please call me and let me know. Phil Davis thought of two more committees to add to our list. Thanks to all who signed up at the January meeting.
PENNIES FROM KEVIN:
Those who were present in the January meeting may recall my announcement to step down as President of the ACT. I desire to spend more time with my fiancée, Leah, and future plans would disrupt my full attention to club matters. The March meeting will be the last I preside over. It has been a great experience working with and getting to know so many of you. Remember that all members present at the February meeting will get to vote on our new meeting place: whether we stay or return to Chapman Hall.
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DAVID'S ASTRO CORNER
FEBRUARY 1999
By David Stine
Everyone should be familiar with the term Messier object by now. If you are new to astronomy, a messier object is a deep sky sight that was either discovered or designated by a French astronomer, Messier. There are a 110 objects designated by an M-number. These objects consist of 28 globular star clusters, 29 open star clusters, 7 galactic nebulas, 4 planetary nebulas, 41 galaxies, and 1 double star. They can be seen at various times of the year in the evenings, however during the latter part of March, it is possible to view everyone of them if you start at dusk and continue to dawn in one night. This is called "Messier Marathon. Every year, the TUVA Astronomy Club in Council Hill/Checotah hosts one of these marathons. Astronomy enthusiasts from various areas of the state and out of the state tote their scopes and accessories to Ron and Maura's farm for an evening of fun and observing. This event is set for Saturday night, March 20, 1999 and Ron and Maura would like to extend the invitation to you. If you have never gone to a marathon at the TUVA Observatory grounds, you are in for a treat as every year there is always something new and exciting that occurs out of the blue. No one knows what it will be, but you won't be disappointed. The farm has a large expanse of open area for you to set your equipment and tent up and very dark skies. Ron has been awarding the person or persons who locates the most Messier objects and the award is called the David Stine Messier Marathon Award, only because I was the first winner. I have won the award twice locating 97 and James Liley has won twice. James holds the all time record with 108 objects. Only one other person has gone over the 100 mark and that was Scott Parker. This will be the 8th Annual Messier Marathon and maybe you may be the first person to locate all 110 objects and break James record. Even if you don't won't to attempt locating the Messier objects, you still will not want to miss this event. A dark sky will enable you to see objects such as the Veil Nebula, Horsehead, and many NGC objects that in any other sight would be difficult or impossible to find. Binoculars will reveal many of these objects.
Plan to get there early, so you can view the sunspots that may be appearing on our star. There are several ways to get to the TUVA site, but the best way is to follow someone that has been there before. I plan on being at the Homeland parking Lot at 3p.m. Saturday at 91st/Memorial and will wait about 15 minutes for anyone that wants to follow me down. Elsewhere in this newsletter there will also be an explanation or map of the route to the site. To prepare for the marathon there are many books out now that are excellent. The Astronomical Leagues Observe Messier Objects takes you through each season and when the best time to observe the various objects. It has pictures and sketches of some of the objects which members have made. Each object has a short description and directions on how to locate each. You can purchase this guide through the Astronomical League for $6. A step up is the Deep Sky Companion called simply The Messier Objects by Stephen O'Meara. This is a hardback book and the newest out on Messier Objects. It has pages of observing tips, most recent scientific data on each Messier Object, accurate drawings of each object, and diagrams and maps. It retails for about $34.95. and can be purchases at local bookstores. Another recent book devoted to the marathon is called The Year Round Messier Marathon Field Guide by Harvard Pennington. This book shows you how to find 17 bright finder stars and 17 constellations to guide you to all 110 objects, A systematical way to locate each object through the sequence of charts provided. This book is also hardbound at $19.95. I also have put together a sequence of charts of the sky using Bright Star Atlas and have divided the sky into sections showing the time of night to see the objects in that part of the sky based on past marathon expieriences. Each section shows the time frame that you have before the object sets. Basically you start with the objects that are setting in the west and go east(and that’s a simple explanation as it is much
harder than it sounds). The cost for a copy of my Marathon Guide is some of your snacks you bring with you, and a look through your telescope. I love chips and cookies. I guarantee that if you are persistent and follow my guide you will see at least 90 objects and possibly all 110. I hope we have clear skies and will see everyone there. That’s it for David’s Astro Corner this month, see you in my corner next month.
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WEB SITE OF THE MONTH
By Rusty Fletcher
Are you interested in computerizing your Dob or Alt-Az mounted Newtonian? If so, this months web-site of the month is the place to get all the information you need. Mel Bartles home page is the place to obtain everything you need to completely motorize and computerize your telescope at a very reasonable cost. Mel Bartles has been a very avid proponent of the computer controlled Alt-Az mounted telescope for many years. He has been an amateur astronomer for the past 25 years and has published articles in "Sky and Telescope Magazine" (April 1979) and "Observatory Techniques" (Winter 1994). Mel gives away the software to control your telescope. It's available to anyone willing to take the time to download it at no cost (a project he has worked on for years). Since the worlds largest telescopes are all nothing more than computer controlled Alt-Az mounted scopes (W.M Keck Telescopes, Gemini 8m, Hobby-Eberly Telescope and many others) it only makes sense that many amateur astronomers are making use of the same technology and turning their large aperture telescopes into computer controlled Alt-Az mounted telescopes. For the first time in recent history the technology exists to completely computerize a Dob or any Alt-Az mounted telescope at very little cost (less than $600.00 if you already own a computer). The web address is:
I hope you enjoy browsing this web site. If you decide to computerize your Alt-Az mounted telescope the next step is CCD imaging which many amateur astronomers are currently doing with their Dobsonian mounted telescopes.
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SKY FORUM
By Don Cole
Saturn, the sixth planet in order of distance from the sun, and the second largest in the solar system. Saturn's most distinctive feature is its ring system, which was first seen in 1610 by Galileo, using one of the first telescopes. He did not understand that the rings were separate from the body of the planet, so he described them as handles (ansae). The Dutch astronomer Christian Huygens was the first to describe the rings correctly. In 1655, desiring further time to verify his explanation without losing his claim to priority, Huygens wrote a series of letters in code, which when properly arranged formed a Latin sentence that read in translation, "It is girdled by a thin flat ring, nowhere touching, inclined to the ecliptic." The rings are named in order of their discovery, and from the planet outward they are known as the D, C, B, A, F, G, and E rings. These rings are now known to comprise more than 100,000 individual ringlets, each of which circles the planet.
Exploration of the Saturn System
As seen from earth, Saturn appears as a yellowish object-one of the brightest in the night sky. Observed through a telescope, the A and B rings are easily visible, whereas only under optimal conditions can the D and E rings be seen. Sensitive earth-based telescopes have detected nine satellites, and in the haze of Saturn's gaseous envelope, pale belts and zones parallel to the equator can be distinguished.
Three U.S. spacecraft have enormously increased knowledge of the Saturn system. The Pioneer 11 probe flew by in September 1979, followed by Voyager 1 in November 1980 and Voyager 2 in August 1981. These spacecraft carried cameras and instruments for analyzing the intensities and polarization of radiation in the visible, ultraviolet, infrared, and radio portions of the electromagnetic spectrum. The spacecraft were also equipped with instruments for studying magnetic fields and for detecting charged particles and interplanetary grains.
The Interior of Saturn
The mean density of Saturn is eight times less than that of earth because the planet consists mainly of hydrogen. The enormous weight of Saturn's atmosphere causes the atmospheric pressure to increase rapidly toward the interior, where the hydrogen gas condenses into a liquid. Closer to the center of the planet, the liquid hydrogen is compressed into metallic hydrogen, which is an electrical conductor. Electrical currents in this metallic hydrogen are responsible for the planet's magnetic field. At the center of Saturn, heavy elements have probably settled into a small rocky core with a temperature close to 15,000 degrees C (27,000 degrees F). Both Jupiter and Saturn are still settling gravitationally, following their original accretion from the gas and dust nebula from which the solar system was formed more than 4 billion years ago. This contraction generates heat, causing Saturn to radiate into space three times as much heat as it receives from the sun.
The Atmosphere of Saturn
Saturn's atmospheric constituents are, in order by mass, hydrogen (88 percent) and helium (11 percent); and the remainder comprises traces of methane, ammonia, ammonia crystals, and such other gases as ethane, acetylene, and phosphine. Voyager images showed whirls and eddies of clouds occurring deep in a haze that is much thicker than that of Jupiter because of Saturn's lower temperature. The temperatures of Saturn's cloud tops are close to -176 degrees C (-285 degrees F), about 27 degrees C (49 degrees F) lower than such locations on Jupiter.
Based on the movements of Saturn storm clouds, the period of rotation of the atmosphere near the equator is about 10 hr 11 min. Radio emissions that have been detected coming from the body of the planet indicate that the body of Saturn and its magnetosphere rotate with a period of 10 hr 39 min 25 sec. The approximately 28.5-min difference between these two times indicates that Saturn equatorial winds have velocities close to 1700 km/hr (1060 mph).
In 1988, from studies of Voyager photos, scientists determined an odd atmospheric feature around Saturn's north pole. What may be a standing-wave pattern, repeated six times around the planet, makes cloud bands some distance from the pole appear to form a huge, permanent hexagon.
The Magnetosphere
Saturn's magnetic field is substantially weaker than that of Jupiter, and Saturn's magnetosphere is about one-third the size of Jupiter's. Saturn's magnetosphere consists of a set of doughnut-shaped radiation belts in which electrons and atomic nuclei are trapped. The belts extend to more than 2 million km (1.3 million mi) from the center of Saturn and even farther in the direction away from the sun, although the size of the magnetosphere fluctuates, depending on the intensity of the solar wind (the flow of charged particles from the sun). The solar wind and Saturn's rings and satellites supply the particles that are trapped in the radiation belts. The rotation period of 10 hr 39 min 25 sec for Saturn's interior was measured by Voyager 1 while passing through the magnetosphere, which rotates in synchrony with the interior of Saturn. The magnetosphere interacts with the ionosphere, the topmost layer of Saturn's atmosphere, causing auroral emissions of ultraviolet radiation.
Surrounding the Saturn satellite Titan and Titan's orbit, and extending to Rhea's orbit, is an enormous toroidal cloud of neutral hydrogen atoms. A disk of plasma, composed of hydrogen and possibly oxygen ions, extends from outside the orbit of Tethys almost to the orbit of Titan. The plasma rotates in nearly perfect synchrony with Saturn's magnetic field.
The Ring System
The visible rings stretch out to a distance of 136,200 km (84,650 mi) from Saturn's center, but in many regions they may be only 5 m (16.4 ft) thick. They are thought to consist of aggregates of rock, frozen gases, and water ice ranging in size from less than 0.0005 cm (0.0002 in) in diameter to about 10 m (33 ft) in diameter-from dust to boulder size. An instrument aboard Voyager 2 counted more than 100,000 ringlets in the Saturn system.
The apparent separation between the A and B rings is called Cassini's division, after its discoverer, the French astronomer Giovanni Cassini (1625-1712). Voyager's television imaged five new faint rings within Cassini's division. The wide B and C rings appear to consist of hundreds of ringlets, some slightly elliptical, that exhibit rippling density variations. The gravitational interaction between rings and satellites, which causes these density waves, is still not completely understood. The B ring appears bright when viewed from the side illuminated by the sun, but dark on the other side because it is dense enough to block most of the sunlight. Voyager images have also revealed in the B ring radial, rotating spoke-like patterns.
Satellites
More then 20 satellites have been discovered orbiting Saturn. Their diameters range from 20 to 5150 km (12 to 3200 mi). They consist mostly of the lighter, icy substances that prevailed in the outer parts of the gas and dust nebula from which the solar system was formed and where radiation from the distant sun could not evaporate the frozen gases. The five larger inner satellites-Mimas, Enceladus, Tethys, Dione, and Rhea-are roughly spherical in shape and composed mostly of water ice. Rocky material may constitute up to 40 percent of Dione's mass. The surfaces of the five are heavily cratered by meteorite impacts. Enceladus has a smoother surface than the others, the least cratered area on its surface being less than a few hundred million years old. (Possibly Enceladus is still undergoing tectonic activity.) Astronomers suspect that Enceladus supplies particles to the E ring, which neighbors Enceladus's orbit. Mimas, far from being smooth, displays an impact crater the diameter of which is one-third of the diameter of the satellite itself. Tethys also bears a large crater and a valley 100 km (62 mi) in width that stretches more than 2000 km (1200 mi) across the surface. Both Dione and Rhea have bright, wispy streaks on their already highly reflective surfaces. Some scientists conjecture these were caused either by ice ejected from craters by meteorites, or by fresh ice that has migrated from the interior.
Several small satellites have been discovered immediately outside the A ring and close to the F and G rings. Possibly four so-called Trojan satellites of Tethys and one of Dione have also been discovered. Trojan satellites occur in regions of stability that lead or follow a body in its orbit around a massive central body such as the sun.
The outer satellites Hyperion and Iapetus also consist mainly of water ice. Iapetus has a very dark region in contrast to most of its surface, which is bright. This dark region and the rotation of the satellite are the cause of the variations of brightness that were noticed by Cassini in 1671. Phoebe, the farthest satellite, moves in a retrograde orbit that is highly inclined to Saturn's equator. Phoebe is probably a cometary body captured by Saturn's gravitational field.
Between the inner and outer satellites orbits Titan, Saturn's largest moon. Its diameter is 5150 km (3200 mi), larger even than the planet Mercury. The diameter of Titan is not known, however, because a dense orange haze hides the surface. The thickness of Titan's atmosphere is probably about 300 km (about 186 mi). Titan has a nitrogen atmosphere with traces of methane, ethane, acetylene, ethylene, hydrogen cyanide, and carbon monoxide and dioxide. On the surface, the temperature is about -182 degrees C (-296 degrees F), and methane or ethane may be present in the forms of rain, snow, ice, and vapor. The interior of Titan probably consists of equal amounts of rock and water ice. No magnetic fields have been detected. The southern hemisphere is slightly brighter, and the only detail visible is a dark ring in the northern polar region.
*** Astronomy Dictionary ***
Declination: (DEC) A coordinate on the celestial sphere, the equivalent of latitude on Earth. DEC is measured in degrees North and South of the Celestial Equator, from 0 degrees at the celestial equator to plus 90 degrees at the North celestial pole and minus 90 degrees at the South celestial pole. It is an (equatorial coordinate).
Right Ascension: (RA) A coordinate on the celestial sphere, the equivalent of longitude on Earth. RA is measured clockwise around the celestial equator, usually in hours, minutes, and seconds of sidereal time, starting from 0 hours at the (vernal equinox). The 0 hour line of right ascension is the celestial equivalent of the Greenwich meridian on Earth. An hour of right ascension is equal to 15 degrees of arc, so that 24th of RA is equivalent to 360 degrees. Right Ascension is an (equatorial coordinate).
>>> From The Cargo Bay <<<
Of the complete STS stack that is launched, are any of the components reusable? If so, which ones? and how are they recovered for use? Actually, there are three components that are recovered for reuse. The first are both SRB's ( Solid Rocket Boosters), after they have expended their fuel supply separate from the external fuel tank. After separation parachutes are deployed and they land in the ocean where they are recovered, prepared and used on another shuttle mission. The other component to be reused is of course the shuttle itself. The main external fuel tank after jettison either burns up in the atmosphere or hits someone on the head. Question : How long (minutes) into the flight (after launch) are the SRB's jettisoned? Who is the person (what position) that actually presses the "Launch" button, when the Shuttle is launched?
So until next month Dark Skies and Steady Seeing to You ...
Reference Material :: "Astronomy, A self-teaching guide." by Dinah L. Moche (4th ed.) "Guide to the Stars" by Leslie Peltier. " Astronomy, For the Earth to the Universe" by Jay M. Pasachoff (3rd ed.)
Astronomy Club meeting dates for 1999.
The club will meet the last Friday of each month except for November and December when a holiday will interfere with the last Friday. The November meeting will be on the 19th, and the December meeting will be on the 17th.
The dates are:
26 March
30 April
28 May
25 June
30 July
27 August
24 September
29 October
19 November
17 December
That’s all folks…