Mississauga Centre RASC

78th Meeting

Speakers’ Night

 

 

Day:                Friday February 9, 2007

 

Chair:                Randy Attwood

 

Speakers:          Ian McGregor, Randy Attwood

                         

                         

The Stars Above, Darkness below

 

Ian McGregor spoke about the significance of Black History Month and Valentine’s Day. March 2007 marks the 200th anniversary of the abolishment of the British slave trade.  Slavery has existed in much of the world since time immemorial and is still present today in many areas.  At Valentine’s, chocolate and flowers are offered as gifts. Historically, 80% of chocolate was produced by slaves, as well as much of the production of flowers. Although present here, slavery was not as economically viable in Canada as it was farther south due to the country’s harsh climate. Ian, in his role as educator, discussed books that grade school children use to learn about slavery.

John Graves Simcoe, the lieutenant governor of Upper Canada in 1791, among his other accomplishments, abolished slavery. As a consequence, escaped slaves from the United States tried to come north via the “underground railway”, especially after the “Fugitive Slave Law” of 1850 in that country.  In 1967 Martin Luther King described Canada as the North Star. How were uneducated escaped slaves to find their way north to Canada?  The problem was to identify the North Star as a guide to keep moving north. The easiest was is to be able to identify the Big Dipper.  Ian showed a large drinking gourd in use in the southern US which has a very similar appearance to the dipper.  The slaves were taught in secret to “follow the drinking gourd” as discovered in a “secret song” of the African Americans. With this clue, many slaves were able to find the north and escape to Canada.

 

Chasing the Moon’s Shadow

 

Randy Attwood spoke about eclipses of the Sun and the activity of chasing the Moon’s shadow. He described the geometry of eclipses, the frequency of at least two per year (varies as 2 to 7), eclipse seasons and types of solar eclipse (partial, annular, total). Other planets such as Mars and Jupiter also experience solar eclipses although on Mars, they can only be partial or annular.  Satellites in orbit around the Earth capture the Moon’s shadow as it passes over our planet.  Solar eclipse paths for many years can be mapped on the Earth’s surface.  Randy described these including the central points of the paths.

Solar eclipses occur when the nodes of the Moon’s orbit line up at new Moon so that the moon casts its shadow upon the Earth. The saros cycle allows similar eclipses to be predicted every 18 years, 10 days.   The length of an eclipse is dependent on the distance of the Moon from Earth and Earth from Sun, the altitude of the Sun, proximity to the equator.

A solar eclipse can be safely observed with projection, solar filter, mylar glasses. During totality, no filter should be used.  Randy described the eclipse experience and the excitement as totality draws near with decreasing light levels, pinhole crescents, shadow bands, Baily’s beads, diamond ring, chromosphere, prominences, corona, 360 degree sunset colours, and the reversal of events as totality ends.  And then, of course, there is the plethora of eclipse souvenirs, philately, tee-shirts etc.

Randy then discussed historical eclipses and showed video clips from the total eclipses of March 198 and March 2006.

 

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