The M.A.S. Newsletter
Journal of the Mauritius Astronomical Society
February 99
A.G.M.
Due to lack of quorum, the
Annual General Meeting has been postponed for the 26th of February at 7hr30 pm at the St
Esprit College, Quatre Bornes.
Schedule for 1998:
Tuesday 16th February:
Meeting at 7hr30 am at St Esprit College for the observation of partial eclipse of
the sun.
Friday 26th February:
Annual general meeting and observation of Vesta at 6.2 magnitude.
Friday 26th March:
Observation of the Moon at 1st quarter.
Friday 30th April:
Observation of Mars near opposition.
Friday 28th May:
General observation night.
Friday 25th June:
Observation of Venus as a crescent and Mercury.
Friday 30th July:
Observation of objects in Scorpius and the milky way.
Thursday 12th - Friday
13th August:
Perseids meteor shower; No Moon!
Friday 24th September:
General observation night.
Friday 29th October:
Observation of Jupiter (near opposition) and Saturn.
Wednesday 17th - Thursday
18th November:
Leonid meteor shower.
Friday 19th November:
Open night; Public invited to view Jupiter, Saturn and a waxxing gibbous Moon.
Monday 13th - Tuesday 14th
December:
Geminids meteor shower.
NOTE:
We suggest that you take note of the above schedule in your diary and should note rely
upon receiving the monthly Newsletter to be informed of the dates of upcoming meetings.
The Newsletter will be sent in the few days preceeding the meeting as a reminder.
Partial Solar Eclipse:
A partial solar eclipse of the Sun is seen by an observer who finds himself some distance away from the trajectory of the Moon's shadow.
On the 16th of February, there will be an annular eclipse of the Sun visible in the southern Indian Ocean and Australia. For observers in Mauritius, only 20% of the Sun will be eclipsed by the Moon. The eclipse starts at 8hr26 am and ends at 10hr09 am.
Solar Eclipses:
A solar eclipse occurs when
the Sun, Moon and Earth are lined up. This may only occur at or very close to new moon.
Moreover, since the Moon's orbit is inclined to the plane of the Earth's orbit by about
5º, solar eclipses do not occur at very new moon. Eclipses of the Sun are only possible
when new moon occurs close to or in the plane of the Earth's orbit. Similarly, Lunar
eclipses are only possible when full moon occurs close to or in the plane of the Earth's
orbit. For this reason, the apparent path of the Sun in the sky has been termed the ecliptic
as eclipses only occur on it. The line of intersection of the plane containing the
Earth's orbit and the plane containing the Moon's orbit is called the line of nodes. To
predict eclipses we need to determine the orientation of the line of nodes. The task is
complicated by the fact that its direction gradually shifts in space, going once round in
every 18.61 years. In any one year, there are at least two - but not more than five -
solar eclipses. Lunar eclipses are about as frequent, but the maximum number of eclipses
possible in a year (lunar and solar combined) is seven.
Annular Eclipses:
An annular eclipse occurs when
the apparent diameter of the Moon in the sky is less than that of the Sun. Then, even when
the Sun and Moon are perfectly aligned with an observer's position on Earth, the smaller
size of the Moon fails to hide the Sun completely and the Sun remains visible as a ring
(annulus).
How to observe?:
NEVER LOOK AT THE SUN THROUGH
BINOCULARS OR TELESCOPES! If you have a pair of binoculars or a small telescope, place a
screen some distance from the eyepiece so as to obtain a sharp image of the Sun on the
screen. To observe a solar eclipse all you need are your eyes and some protection. As
protection you may use glass panes blackened with soot or old negative films.
Vesta:
Vesta is the third largest asteroid known and also the brightest (sometimes reaching a visual magnitude of 6). On the 7th, Vesta is in the constellation of Cancer and at its closest (1.46 AU)
Serge Florens, Secretary