Mississauga Centre RASC

70th Meeting

Members’ Night

Day:                October 20, 2006

Chair:         Randy Attwood

Speakers:   Roy Swanson

Bob Anderson

                   William Callahan

                   Randy Attwood

                   Ian McGregor

                   Jim Jackson

November 2006 Night Sky

Roy Swanson spoke about the November Sky. No visible planets are present in the evening sky. There is a transit of Mercury on November 8. Roy also spoke about the probability that the 13th day of the month is a Friday. Although in the past 400 years there is a tiny increased probability of this, over the long term, the day of the week randomizes.  Finally, Roy described Foamhenge, a reproduction of Stonehenge, and discussed the alignments of the monument.

An intergalactic interlude

Bob Anderson showed a video of his astroimages taken from Mississauga, including the Moon, M33, M42, Blackeye galaxy, Crab Nebula, the Horsehead, the Bubble Nebula, the North America Nebula, the Veil various globular clusters, Jupiter, Saturn and other objects. 

Transit of Mercury, November 8, 2006

William Callahan spoke about the upcoming transit of Mercury. After cautioning the audience about solar observing, he described what is a transit, and transits of Mercury, Venus, and planet transits over one another as Venus crossing in front of Jupiter in the 1880’s and 2600. Historically, transits, especially of Venus, have been important for calculating the astronomical unit.  Mercury crosses the face of the Sun 13 times per century, with events occurring at intervals of 3.5, 7, 9.5, 10 and 13 years. The transits of 1960, 2006 2056 all belong to the same series. Due to orbit eccentricities, there are twice as many transits in November as in May and at any given time, about 6 series are running. As in an annular eclipse, there are 4 contacts in a transit: when the planet first touches the Sun’s limb, internally touches it and the reverse.

For the upcoming event, William gave the times and position angles, and noted that the Sun would set before the last two contacts. He recommended looking for the black-drop effect, doing timings, and using a magnification of 50x to 100x. 

DVD lending library

Randy Attwood announced that the Mississauga Centre now has a library of 25 DVD’s for lending. He thanked Terry Hardman for his generous contributions to this library.

Antikythera

Ian McGregor talked about the Antikythera mechanism which was found in a Greek shipwreck of 80B.C. among a shipment of marble statues and pottery. The mechanism is the size of a shoebox and has been extensively studied including with x-rays since the 1950’s. It appears to be a geared mechanism with interlocking teeth and may be an astronomical computer related to the cycles of the Sun, Moon, Mercury and Venus. Most recently, a committee of astronomers, physicists and chemists have proposed that it is the earliest known computer, very advanced for its time.

Ian also spoke about a star party in the London area which he found out about through a free metro paper on the subway. He is also planning to start an introductory observing course in February, oriented towards the RASC certificates. 

Pernicious Precession

Jim Jackson did some research on the effects that precession would have on sunlight streaming through openings of ancient monuments. This had been brought up at a previous meeting where the question had been raised as to whether precession should affect this. Jim noted that the pole position but not angle of the Earth’s axis to the ecliptic changes with time, with the equinox precession a full 360 degrees in 25,600 years.  As a result, there should not be any change in sunlight through openings at a certain season.

Submitted by Chris Malicki, Secretary  Chris Malicki, Secretary                               back to Miss Centre. meeting reports page
Mississauga Centre RASC