Space - Tullamore Astronomical Society

UPCOMING ASTRONOMICAL EVENTS
Compiled by John Flannery, South Dublin AS
Summary
Winter Solstice occurs on December 21 st at 18:35hrs:
Winter officially begins in the Northern Hemisphere.
Eclipses
No eclipses occur during this time.
The Planets
Heads
Binocular users may just about spot Mercury in the
evening sky around time of greatest eastern elongation on
November 3 rd (24°) given a clear south-western horizon.
Your best chance of seeing the planet falls during
December in the morning sky. Mercury begins December
about 5° above the south-eastern skyline at the beginning of
civil twilight and climbs higher each day until greatest
western elongation (21°) on the 12 th when it can be found at
an altitude of 9.5° around the same time of morning.
Thereafter, it slowly retreats sunward (but remains quite
bright at magnitude -0.4) and will probably be lost to view
by New Year’s Day. A word of caution; if you are looking
for Mercury in any sort of optical instrument make sure you
do not accidentally sweep up the Sun in the field. It
therefore makes sense to look for the planet in binoculars or
a telescope after sunset or before sunrise. Advanced
amateurs do observe the planet in daylight close to the Sun
but only by taking careful precautions and having
telescopes with setting circles that allow you to accurately
“home in” on Mercury’s position in the sky.
Venus has remained quite low in the evening sky all year
but is now beginning to pull clear, gaining in altitude
during the two-month period covered by these notes. It lies
highest in our evening skies in mid-December (still only
about 12 in altitude though) and reaches greatest brilliancy
on December 9 th (magnitude -4.6).
Telescopes will show the phase of the planet
change from half to a thin crescent over the next two
months, while the diameter of the disk swells from 24.5" to
55". You should be able to spot Venus as a tiny crescent in
binoculars by the end of the year. The Moon is nearby on
November 5 th and December 4 th , making for an attractive
sight.
Still awaiting launch at time of writing is the
European Space Agency’s Venus Express mission,
designed to study the atmosphere and space-environment of
Venus. Following launch, the spacecraft will take 153 days
to reach Venus after which it will settle into orbit and begin
science operations. Although previous missions such as
Magellen have used radar to pierce the veil shrouding this
mysterious world, we are still no closer to understanding
UP
why Earth’s sister planet boasts a greenhouse effect run
riot.
Mars continues to steal the show as it reaches opposition
on November 7 th in the constellation Aries and shines at
magnitude -2.3 throughout the night. The disk measures
20" at this time and the Red Planet is sure to be carefully
scrutinised by backyard observers. Or so we hope! Recent
reports on the International Mars-watch page
(http://elvis.rowan.edu/marswatch/) suggest that a dust
storm first noticed brewing on the planet in mid-October
has now increased in intensity. Should the storm grow in
size it will gradually obscure features for observers and the
disk will look bright orange. Any reports you have should
be forwarded to the Mars-watch web site mentioned above.
A detailed article on observing the planet during this
apparition can be found at
http://www.tnni.net/~dustymars/Article_2005.htm The
Moon is close to Mars on November 14 th and December
11 th .
Jupiter necessitates an early rise as it is strictly a morning
sky object during November and December. You will
probably only first spot the cream-coloured planet from the
second week of November onwards as its time of rising
becomes progressively earlier ahead of the Sun. Jupiter
shines at magnitude -1.7 at the moment and the disk is quite
small (for Jupiter!), measuring 32". The planet moves from
Virgo into Libra at the start of December. Look for the
Moon nearby on the mornings of November 29 th and
December 27 th .
Saturn rises before midnight at the beginning of
November and a little earlier each night until the end of the
period covered by these notes. It brightens slowly from
magnitude 0.3 to magnitude 0.0 during November and
December as it closes in on its January 2006 opposition
date.
The beautiful ring system is easily visible in a
small telescope but if you’ve been keeping a keen eye on
the planet the last few years you will notice that they are
gradually closing up -- their Earthward tilt is now around
17.5°. It’s all to do with the inclination of Saturn’s orbit
and ours; twice during Saturn’s 29 year long circuit of the
Sun the rings appear edge-on to Earth-based observers as
we pass through their plane. The rings will next be edge-on
in September 2009 and will disappear from view in all but
larger amateur telescopes.
The Ringed Planet is still a dramatic sight at the
moment close to the Beehive star cluster in Cancer that was
mentioned in the previous issue’s notes. With the Moon
close to the planet too on the evenings of November 22 nd
and December 18 th it will add to an already dramatic sight
in binoculars.
Details for Uranus, Neptune, and Pluto are beyond
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Réalta – Volume 7, Issue 2 – November/December 2005 – Tullamore Astronomical Society