Perseids
Perseid meteor shower peaks on Sunday August
12, but for several nights either side of this the display should
be well worth watching. You can start viewing as soon as it gets
dark, as this year's display coincides with the new moon - so the
skies will be exceptionally dark.
Meteors (or "shooting stars") are tiny pieces of dust
that have fallen off a comet - Comet Swift-Tuttle in this case,
last seen in 1992 and not due back until 130 years after that.
When Earth collides with them in space at 60 to 70 km per second
they burn up in a short fiery flash usually lasting less than one
second. Each piece of dust is typically the size of a grain of
sand and the 'burning up' takes place 100 km above the ground.
Larger dust particles are rare but give much brighter meteors
which can often leave a glowing trail behind them for several
seconds which we call "trains".
The darker your sky the more Perseids you will see. There are many
more faint Perseids than bright ones. Try to get away from
streetlights. Rural observers could see one or more Perseids every
minute, which is 10-20 times more than the normal meteor rate.
This rate is 5 to 10 times more than suburban observers may see
due to their brighter sky background swamping the fainter meteors.
Give your eyes at least 5 minutes to get used to the dark. Try to
view for at least one hour.
Record your start and end times (and any breaks you take) and send
a count of how many you see. If partially cloudy send an estimate
of the fraction of the area you watched that was covered by cloud
on average. Please send your notes to observe@astronomy.ie
and we'll publish you in our magazine as a permanent record of the
2007 Perseids over Ireland.
Where to look? Anywhere! Perseids can appear in the North, South,
East, West or even overhead. If there is partial cloud cover look
in the clear patches. If you extend the path of a Perseid seen
anywhere in the sky it should point back to the constellation of
Perseus (hence the name) in the Northeast, just left of the famous
'W' of Cassiopeia. However, this is the worst place to look so
look to left or right, or above, Perseus if you have a 100% clear
sky.
Further details of the Perseids start on page 27 of the August
2007 issue of Astronomy Ireland's magazine (aimed at the general
public). Order a single copy or a full 12-month subscription here
and join in the fun for little more than 3euro a month: www.astronomy.ie/sub
We'll be publishing any photos we
receive in our magazine (send to gallery@astronomy.ie).
TELESCOPE: you don't need one for Perseid
viewing! The naked eye is the best thing to use. So you have all
the equipment you need for best viewing of the Perseids!
There's lots more to see all year round if you do have a
telescope. Astronomy Ireland runs the only dedicated telescope
shop in Ireland (now one of the biggest in Europe). Drop in and
see the huge range in our showroom in Dublin 5 (link to map.html).
Or call and we'll deliver the right telescope for you anywhere in
Ireland - and binoculars (large and small), books, advice etc.
After that, as your national astronomy society, we can advise you
of how to use it for many years to come.
David Moore
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