Mississauga Astronomical Society
                                                                            Fifteenth Meeting
                                                                            Members’ Night

Day:                Friday, February 6, 2004


Speakers:   Randy Attwood
                    Ian McGregor
                                    
 

Randy Attwood showed the latest images from the internet related to the Mars Rover missions.  Whereas the panorama from Spirit was a reddish colour and a rocky plain, the Opportunity site was considerably darker with a flat surface. The Spirit site is named the “Columbia Memorial Station” with hills 3 km away named after the Columbia astronauts. In a similar vein, the Opportunity site is the “Challenger Memorial Station.”

Randy demonstrated the sky as seen from Mars using Starry Night Pro software. In the equatorial sky over Gusev Crater, Orion was seen “upside down”; the sky rotated around the north celestial pole in Draco.  The moon Phobos, which requires 1/3 of a day to rotate around the planet moved rapidly across the sky (20 min to go the length of Gemini). Deimos, on the other hand was nearly “geo” stationary.  The planet Jupiter was visible in Virgo, and Earth at mag -2.5 in Virgo near the Libra border.  Earth’s moon is also a naked eye object from Mars.

 
Hematite, meteorites and time

Ian McGregor started his presentation by discussing gray hematite, an iron oxide. It is especially relevant now with the landing of the Rover “Opportunity” in Sinus Meridiani where the hematite on Mars is located. Ian pointed out that hematite can form from igneous sources but is mostly produced by sedimentary processes, especially water. He brought a sample of gray hematite from the mineral collection of the Royal Ontario Museum. Opportunity Rover will try to ascertain whether sedimentary processes and hence water formed the Martian hematite.

Ian discussed the Martian and lunar meteorites in the R.O.M. collection.  Martian meteorites were first discovered 100 years ago and are difficult to classify as other meteorites. The first shergottite was discovered in India in 1865; the nakhlites come from a 1911 fall in Egypt , and the cassignites from a fall in France in 1815.  Only 20 years ago was it realized that the composition of the air in the pockets is identical to the martian atmosphere especially with the Argon isotopes. To date 28 falls with a total of 85 kg have been identified as being of martian origin.

In contrast, there are only 9 kg of lunar meteorites represented by 55 meteorites of 20 different falls. These meteorites, which come from lunar highlands are much different than the moon rocks from the lunar maria brought back by the Apollo astronauts.  Ian encouraged the audience to visit the upcoming meteorite exhibit at the R.O.M.

Ian then discussed the astronomical origin of time units. Ancient Egypt was the first to use a solar calendar whereas previous civilizations used the lunar calendar. The Egyptians figured out how many days there are in a year. They also divided the day into 24 hours because during the night 12 of their constellations would rise; if another invisible 12 rose in the daytime there would be 24 divisions in a day.  Babylon, with its base 60 mathematics established the number of seconds in a minute and minutes in an hour. The Romans created a seven day week based on the god/planets which included the sun and moon. Germanic influences named Wednesday (Woden, or messenger Mercury), Thursday (Thor or Jupiter), and Friday (Freya or the goddess Venus).  Rome also divided the year into 12 months and began the year in January (named for the god Janus with its two faces looking into the past and future).

 
NASA Mars Newsbriefing

Randy Attwood showed a videotape of today’s press conference about he latest news from the Mars rovers.  Spirit had made a fantastic recovery. The flash memory has been erased and re-set. The engineers described the flash memory problem and used the cripple mode to stabilize and de-bug the system.  Spirit had run out of memory and kept re-setting.  The file system was corrupted and was re-initialized. Images of Adirondac  rock before and after grinding by the rock abrasion tool were shown. Adirondac looks like a volcanic rock.  Instruments on the Opportunity rover were being initialized. Opportunity drove 3 ½ meters yesterday and was to drive a further 1.6 meters today. 
 

Other business

 John Boyd discussed the upcoming transit of Venus and asked for people interested in a measurement project to link up with other astronomy groups.

Randy Attwood asked the group for suggestions about membership interests, speakers during meetings. In general, the members were enthusiastic about the quality of meetings to date and proposals were made to mix novice and expert material.

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