Mississauga Astronomical Society
                                                                            Seventeenth Meeting
                                                                            Members’ Night

Day:                 Friday, March 5, 2004

Chair:         Phil Mozel

 Speakers:   Brian Cheaney
                   Guy Nason
                   Scott Young
                   Randy Attwood                   

The sky Tonight

Brian Cheaney again gave a presentation on current sky events. He started by showing slides of the February Moon-Venus conjunction, and sunspots observed during his school astronomy programs.  Coming events to watch for are Jupiter shadow transits especially the triple transit on March 28, the Moon-Venus conjunction of Mar. 24 and Mercury visibility.  Springtime shows us the realm of the galaxies. Brian challenged us to look deep into outer space at the M65, M66 and M95 and M96 groups in Leo, M94 and M101, and M81 and M82.  M101 is a good challenge in light-polluted skies but should be easy in a 6” telescope. He suggested quarterly star parties with the next for Mar. 20 at Forks of the Credit Park.

Portlandia Occultation

Guy Nason in November had asked  M.A.S. members to observe an occultation of an 8.2 magnitude star in Pisces by the asteroid (757) Portlandia on Dec. 7. He now presented the results of this occultation. This occultation was easy because of the brightness of the star and at the same time difficult due to the event happening shortly after twilight (sun 16degrees below the horizon), not giving the observer much time to locate the relevant star. Accurate timings enable the orbit of the asteroid, its shape and the position of the star to be refined with more accuracy. Videorecording or visual observation with time signals recorded on a tape recorded are both acceptable methods.

Guy showed on a map the location of Ontario observers and described their results. Clouds hampered many especially in the Haliburton and Ottawa areas.  Of approximately 9 stations that recorded an occultation, the most spectacular was the David Dunlop Observatory – the largest telescope ever to observe such an event. A video of the occultation taken at  the DDO showed the star disappearing in stages because of the close graze. An ellipse of shape suggests the asteroid is 30 by 34 km.  

Manitoba Museum and Planetarium

Scott Young, the Manager of the Planetarium and Science Gallery at the Manitoba Museum in Winnipeg spoke about his work at the Museum. Scott became interested in astronomy on Feb. 26, 1979 at the age of 8 when he pulled back a window curtain and saw the total eclipse of the sun in all its glory. He started his career through the Royal Astronomical Society of Canada and then the planetarium attached to the Manitoba History Museum. He spent his earlier years touring the larger towns of the  province and northwestern Ontario with a mobile planetarium.  The current planetarium has a 30 year-old Zeiss projector, a piece of equipment which is slowly becoming extinct as planetaria, including the Winnipeg Planetarium, go to video projection systems which will eventually cover the entire dome. Even slide projectors used at present are becoming slowly obsolete.

The closing of the McLaughlin Planetarium in Toronto was a wakeup call to other institutions to modernize their shows. A planetarium cannot compete with movie theaters showing multimillion dollar productions; therefore the planetarium should concentrate on what it does best: observing. In Winnipeg, video from the roof projects live images of the Sun, Mars, etc. inside; or a NASA videofeed can be shown. Because of rapid astronomical events such as Mars rovers, comets, Cassini etc. shows are no longer planned far in advance. Advertising is done by news media which publicize current events.  Scott urged the Toronto area to again open a planetarium. It is much easier and cheaper now to produce shows and there is no better time than now.

Beginner Astronomy: Observing the Moon

Randy Attwood presented the first of a series of talks about basic observing. The Moon is the easiest object to observe. Randy described the size, distance, orbit, phases, apogee and perigee, orbital inclination, dark and light features, and librations. Much of the information is readily available in the Observer’s handbook of the RASC.

Tidal lock causes one side to face the earth but librations enable us to see more than 50% of the surface at various times. Mare Crisium is a good gauge of east-west libration. The far side with its lack of maria is much different than the near side. Light features are generally cratered highlands whereas the maria, or seas are flatter less cratered regions. Young rays like Tycho are distinguished by bright rays.

Full Moons have a specific name for every month such as the well known Harvest Moon of September and the lesser known Worm Moon of March.  Naked eye observers can note the Moon’s position from night to night, or to locate the constellation of the full Moon in each month and to notice the elevation depending on time of year (low in summer, high in winter).  Earthshine can be observed, and especially the subtle bluish tinge caused by the earth’s colour.  Binoculars show craters, seas etc. whereas a telescope can show hundreds of objects.

Lunar occultations, listed in the Observer’s Handbook are valuable to observe. Eclipses take place when full or new Moon is close to a node. Randy also described the Moon illusion whereby the size appears greater when close to the horizon, and the “man in the Moon”.  Finally he described lunar atlases such as Rukl “Atlas of the Moon”, and lunar software such as “Virtual Moon Atlas” www.astrosurf.com/avl. or lunar phase software.

 Submitted by Chris Malicki, Secretary  Chris Malicki, Secretary                               back to M.A.S. meeting reports page
Mississauga Astronomical Society