The
Group Newsletter
No.169 07/11/09
The last
meeting was again quiet, with a dust and smoke haze limiting the observing to
the brightest objects, for the three members present to view. The chance of
another dust and smoke haze is very low, however the same can not be said for
the likelihood of cloud cover at this months meeting. This will be then last
meeting for this year, and this is the last newsletter for this year. I hope
the group’s members enthusiasm survives the wet season
and they will be ready to start observing again next year. I don’t have any
local news, so I have included extracts from a “Sky and Telescope article
below. Hope to see you at the meeting,
James.
About a decade
ago, mid-November's normally benign Leonid meteor shower exploded like
fireworks into prominence, giving us dazzling displays of shooting stars almost
too numerous to count.
Chris Peterson / Cloudbait Observatory
I remember
these celestial spectacles as if they were yesterday. In 1999, I was flying in
a research jet in the darkness over
If new
predictions by meteor specialists hold true, we could be in for a repeat of this
celestial treat in 2009. That's because last November, despite strong
interference from moonlight, observers in Europe, Asia, and the
The Leonids are bits of debris spread along the orbit
of a periodic comet named Tempel-Tuttle,
which has a 33-year-long orbit that can bring it rather close to Earth. (In
1366, for example, it passed only 2 million miles from us, one of the very
closest passes that any comet has made in recorded history.)
Each time it rounds the Sun, Tempel-Tuttle spews out a ribbon of dust that remains fairly concentrated
for centuries as it follows the comet around in orbit. During the 2008 pass,
Earth came rather close to the debris ejected in 1466, about 16 orbits ago.
Although aware of this stream's proximity, few meteor specialists expected much
from it. (One who did was Russian dynamicist Mikhail Maslov.)
With the sudden realization that this 542-year-old ribbon of rubble still packs
a punch, everyone's gone back to the drawing board to recalculate next year's
circumstances. The main peak of activity will come on November 17th and involve
contributions from the comet's spewings in 1102,
1466, and 1533. On that much, at least, three teams' calculations agree. But
otherwise their results, like the meteors themselves, are scattered:
• Maslov predicts
a brief outburst of 170 to 180 meteors per hour centered
at 21:35 UT, with smaller secondary peaks (20 to 25 per hour) on November 16th
at 13:30 UT and again on the 18th at 19:24 UT.
• Jérémie Vaubaillon (Caltech) initially predicted a maximum of
nearly 500 Leonids per hour at 21:43 Universal Time.
He has since scaled back his expectations and now predicts a maximum closer to 200 per hour,
with the peak perhaps delayed by 30 minutes to 1 hour.
• William Cooke (
Fortunately, the Moon will be just past new on the
17th, so skies should be good and dark. Unfortunately
for those of us in the
Posted by
Kelly Beatty, December 10, 2008
Next Meeting
Date:14/11/09
Time:7:30
pm.
Place:James Bak
White Rock Qld 4868