North American Meteor Network
The eta Aquarid
(ETA) meteor shower reaches a maximum on May 5th this year, at
about 23 hours Universal Time (UT). This is a particularly interesting
shower as it is debris from the famous Halley's Comet.
These are
fast meteors, travelling at about 66 km/sec, and will seem to
come from an area in the sky located at 338 degrees ie. RA 22h
31.8m, Dec -01, which is very near the star eta Aquarius on a
star atlas. This is known as the radiant for the shower. Check
out the maps of the sky on the NAMN website at http://web.infoave.net/~meteorobs/charts.html.
Aquarius is
on Map #3, and can be printed off by setting your printer to landscape
mode. Also check out the map of the eta Aquarid radiant itself,
on the International Meteor Organization (IMO) website at the
following address: http://www.imo.net/calendar/cal00.html#eta-Aquarids.
The radiant moves a little bit from night to night.
The Zenithal
Hourly Rate (ZHR) for this meteor shower is about 60 meteors per
hour with the unaided eye. This is the number of meteors, on average,
that an observer would see from a dark country sky if the radiant
was directly overhead. Your latitude and your time of night will
affect your meteor rates, as they affect how high the radiant
is in your sky. Unfortunately, we also have a bright moon for
this year's eta Aquarids, so the faintest meteors will not be
seen. Eta Aquarid meteors can be seen in lesser numbers until
about May 28th.
However, it
is still a treat to see this comet debris! Try to block the moon
from your field of view. This will help you see more meteors.
The nights around the date of maximum are also worth observing,
besides just the main night, as there may be some other small
peaks of meteor activity, perhaps even until about May 10th. You
can help us out by trying to get data for some of these other
nights.
Each one of
these meteors is a streak of light produced when a small particle
of debris from Halley's Comet strikes our Earth's upper atmosphere
and burns up due to friction. These particles have been shed by
the parent comet many years ago. In fact, each time the comet
passes through our solar system, a new path of debris is created.
The path of debris that we encounter in one year might not be
the same filament of debris that we encountered in a previous
year. This is one reason why meteor shower rates can vary from
year to year.
For more information
on what to record when you watch meteors, check out our NAMN Observing
Guide at: http://web.infoave.net/~meteorobs/guide.html.
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