Mississauga
Astronomical Society
Thirteenth
Meeting
Members’ Night
Day:
Friday, January 9, 2004
Chair: Phil Mozel
Speakers: Denis Grey
Brian
Cheaney
Ian
McGregor
Getting More out of
Astronomy with the RASC Observing Certificate Program
Denis Grey, editor of Scope
Magazine of the Toronto centre RASC, co-author of the ETU
certificate, and
RASC member since 1995 spoke about the certificate program of the
society. He contrasted observing in
which the
individual knows what he/she is looking at, analyzing its size, taking
time to
see the object at its best and seeing its
subtlety while understanding its context, as opposed to peeking
in which
the person merely takes a quick look without appreciating the object.
There
are various classes of
objects to observe. The moon is a good stating point for beginners. It
can be
observed from the centre of the city as can the planets. Double and
multiple
stars are also appropriate for the urban astronomer.
Deep sky is best from a dark site. Variable
star observing has been transformed from writing and mailing of reports
to
internet reporting and immediate feedback. Finally comets and asteroids
can be
found and observed. Certificate programs
of the RASC are structures around one or other of these objects and
generally
highlight the best of the category.
The
“Explore the Universe”
program requires the candidate to observe a minimum of 55 of 110
objects, and
to explore from each category of constellation, bright star, best deep
sky,
solar system, moon and optional variable star. This program encourages
the
beginner to develop an observing plan, learn concepts such as RA, dec
and PA,
and learn the sky.
The “Messier” is
the original
RASC certificate, historical in
accenting the Messier objects. Denis pointed out that 60 of the
Messiers are
easy, 40 challenging, and 10 very difficult. Many are binocular objects.
The “Finest NGC”
certificate,
developed by Alan Dyer, is unique to the RASC and highlight 110
outstanding
objects not in Messier’s catalogue, and which are accessible from
Canadian
latitudes.
Finally a new lunar
observing
program and certificate named after Isabel Williamson is under
development and
will give a guided tout of the moon. It is expected for summer of 2005.
Denis pointed out
that the
Astronomy League Clubs have over 20 different observing programs and
certificates appropriate to beginners, advanced observers, topical
objects,
binocular observers etc. Especially noteworthy is the Saguaro Astronomy
Club
with is forms and large database. www.saguaroastro.org
Denis encouraged
observers to
use of forms and logbooks. Applications for certificates are available
at the
RASC website at www.rasc.ca.
The Sky Tonight
Brian
Cheaney spoke about January observing. Venus is now prominent in the
west and
Mars is still readily visible. Saturn and Jupiter round out the late
evening
sky.
The
winter Milky Way is more subtle than that of summer. Brian listed 8
open clusters
for his observing challenge, the naked eye Beehive M44, the very
ancient M67,
and the clusters M48, M50, M46, M47, M93, M41. Considering that there
was an
imaging failure in the lecture room, the presentation was well given
and
enjoyed by the members.
The Maya and
Venus
Ian
McGregor gave a fascinating talk about the ancient Maya of the Yucatan and the planet Venus. Ian
is very interested in the Maya, has visited their archeoastronomy sites
and has
taught numerous courses on Maya astronomy. The subject is relevant
especially
now because Venus is undergoing the best evening apparition in 8 years,
which
will culminate in the June 8 transit.
These apparitions repeat in this way because 5 synodic periods
of Venus
are the same length of time as 8 earth years.
The
Maya, keen observers of the sky, had a very great astronomy tradition.
Venus
was the god of war, and its appearance a signal to go to war.
Consequently,
observations of the planet were of utmost importance. The
Maya were able to predict the position of
Venus in the sky with an accuracy of 3 hours in 1000 years.
Ian
described the Dresden Codex, the most famous of the surviving Maya
texts. The
Codex has many glyphs or symbols representing Venus. Venus glyphs also
occur at
various Maya archeologic sites such as Uxmal. The Codex
itself has 100 pages folded in
accordion fashion. It represents a specific time interval and as such
can be
compared to an Observer’s Handbook for a given year. Just as current
astronomy
has a Julian number for each day, so did
the Maya have a long count starting in 3114 BC in which each day was
numbered
from that time. This, together with the
number zero (0) in the Maya mathematics, enabled the Maya to make such
precise
calculations.
Ian
explained Maya mathematics to the base 20 with its symbols of shell =
0, dot =
1, and bar = 5. The numbers 236, 90, 250
and 8 are repeated many times in the Codex. Ian showed how in the Maya
sky,
Venus would be visible for 236 days as a morning star, then disappear
for 90
days at superior conjunction, then reappear for 250 days as evening
star and
finally disappear for 8 days at inferior conjunction. The total of
these four
intervals equals the synodic period of Venus of 584 days. Thus the Dresden codex is a calendar of
Venus. Other numbers in the Codex are correction factors because the
intervals
of Venus visibility are exact intergers. Finally,
Ian explained that significant events
in the Maya calendar correlate with planet dates such as the stationary
point
of Jupiter in its orbit.
Submitted by Chris Malicki,
Secretary
Chris
Malicki, Secretary
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Mississauga
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