Mississauga Astronomical Society

Nineteenth Meeting

Members’ Night

Day:                Friday, April 2, 2004

Chair:         Phil Mozel

Speakers:   John Boyd

                   Jim Kendrick

Randy Attwood

Occultations, Eclipses, Transits and things that (apparently) go bang in the Night

John Boyd spoke about astronomical phenomena related to shadows and one object covering another i.e. transits, eclipses and occultations. Two sources of light in the sky are the sun by day and stars at night. Controlling issues in phenomena are size of the source, distance of the observer, location and timing. John illustrated how these factors explain asteroid occultations, types of eclipses of the sun and moon, lunar occultations and grazes allowing mapping of the moon’s edge, extrasolar planet observations and more.  

Observers can note the dimming and brightening of objects, timings, co-ordinating observations with others. Safety is an issue with solar observations with proper filtering such as metallized plastic filters, H alpha or Ca interference filters.  John reminded the audience that damage can easily ensue to telescope optics and eyepieces when projection methods are used especially with Schmid Cassegrains and Maksutov scopes. Other observing factors are timing and location on the earth’s surface, distortions by earth’s and planetary atmospheres. Depending on the type of phenomenon, naked eye, binoculars or telescopes are used. Timings can be as simple as clock/watch, time signals with tape recorder, still camera with clock recording, video recording with time signals or CCD drift. GPS signals or web-based timing can also be used (not as certain due to propagation delays).

For the transit of Venus on June 8, 2004, only contacts III(at 11:05:21 UT) and IV (11:25:23) will be visible from Mississauga. Contacts II and III occur when the black drop effect breaks or forms.  The orbit of Venus is inclined 3.4 degrees to Earth’s. As a result, the two planets and Sun can align only in the months of June and December.  Historically, Venus transits can be used to determine the absolute scale of the solar system. Greatest elongations of Venus allow calculation of the distance ratio Earth-Sun to Venus-Sun. Subsequently, the parallax of Venus as seen from different places on Earth during a transit, allow the absolute distances to be calculated.  John invited members of the M.A.S. to participate in the transit project with accurate timings of contacts from a known location. He recommended the site www.transitofvenus.org as the best website for Venus transit information.

New Observing Aids

Jim Kendrick of Kendrick Astro Instruments, www.kendrick-ai.com described and demonstrated three new products that he has developed. The Ultimate III light-weight aluminum observing chair (16lbs.), which is always level at variable heights, and optional tray can be combined with a ladder accessory for use with a large Dobsonian. Kendrick is well known for his dew removers. The new digital Premier Power Controller, containing temperature and humidity sensors, can be programmed for a number of functions i.e. close to the ambient dew point. The controller is especially useful in a fixed observatory and can be remotely programmed.

NASA Mars Rover video

Randy Attwood showed a NASA video from April 1 giving engineering and scientific updates of the Spirit and Opportunity rovers. Both spacecraft area now near the ends of their nominal missions and have sent back over 20,000 images. Most radio relays are now being carried out via Mars Global Surveyor and Mars Odyssey; occasional direct Earth contact is required to establish the exact time. A spectacular panorama of Mars was shown (as an analogy to the panorama from the Lion King).

Lowell observatory

Phil Mozel showed slides from his trip to Flagstaff Arizona’s Mars Hill Lowell Observatory.  He described and showed the 24” refractor used by Percival Lowell to study and described Martian “canals” and the 13’ telescope used by Clyde Tombaugh to discover Pluto, as well as P. Lowell’s tomb.

Announcements

Phil Mozel described the astronomy exhibit at the Ontario science Centre.     

Paul Brandon spoke about the Yahoo website and M.A.S. chat group, and encouraged members to use this group.

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