Maine
Nature News
|
|
|
Quick Jumps:
General
advice | Meteor shower timetable | Table notes | Key to lunar phase icons | Helpful
websites | Home |
Adapted from
image courtesy NASA's |
Maine
Nature News
|
|
|
Quick Jumps:
General
advice | Meteor shower timetable | Table notes | Key to lunar phase icons | Helpful
websites | Home |
Adapted from
image courtesy NASA's |
General advice for observing Meteors
Each
meteor shower is named for the
constellation – major grouping of stars -- from whose direction the
meteors will appear to radiate. Obtain and use a star chart
to familiarize yourself with the night sky on your observing date. Many
meteor shower radiants do not rise before midnight, making
observation best between midnight and morning twilight. Plan your
observing session as close to the date/ time of shower peak as
possible. Find a dark observation site, as far from outdoor lights as
you can.
Moonless skies are the most favorable. Even at
crescent or quarter phases you may be able to work around moonlight
interference by observing before moonrise, or after moonset. However
meteor showers which occur near the time of gibbous or full moon give
little such leeway.
Allow time for your eyes to adjust to dark
conditions. If you must have light to consult a star chart or to make
notes, use a dim
flashlight whose lens is covered with red cellophane.
Telescopes or binoculars are not necessary. A reclining lawn chair, a
large
boulder with a slanted surface to rest your back against, or a sleeping
bag on the ground
are the most comfortable ways to go. Dress for conditions 10 or 15
degrees F. colder than the actual air temperature, as you will be
sitting still for long
periods of time.
Direct your gaze a bit above the midway point between the
horizon and the zenith, in the general direction of the shower
radiant, without concentrating on any one spot. Then your
peripheral
vision will alert you to the sudden appearance of a meteor. The
word "shower" is
very figurative. Have patience and enjoy
Nature's show!
Notes:
Major Showers are named in bold.
Dates in parentheses are uncertain or variable.
Peaks in parentheses show showers with diffuse activity profiles.
Peak hour given when available. Some peaks occur in daylight
hours, Eastern Time. Remember, the Cosmos does not
necessarily favor the East Coast of the USA!
Meteors' speed is based on average velocity and "is mainly dependent on
whether the meteoroids are traveling in a similar direction to the
Earth, or colliding with us head-on as we orbit around the Sun."
(6)
My informal speed rating scale: Very fast = 60-73 km/sec; Fast =45-59 km/sec;
Moderate = 30-44 km/sec; Slow = 18-29 km/sec. The impression of
speed will vary depending on the angle at which meteors approach in
your view of the sky.
Sources:
(1) American Meteor Society page
(2) NASA Marshall Space Flight Center page
(3) Lew Gramer’s meteor
page
(4) American Meteor Society "FAQ" page. Example
based on suburban night skies lit by a quarter moon.
Your luck may be better or worse -- check the Moon's phase for
your observation date.
(5) NASA's
Jet Propulsion Laboratory meteor table page
(6) Astronomical Society of New South Wales page
|
Phase |
Symbol |
Moon's approx. |
Likely interference for late evening observation |
Phase |
Symbol |
Moon's approx. |
Likely interference for late evening observation |
| New Moon |
|
0 | None | Full Moon |  |
15 | High |
| Waxing Crescent |  |
4 | None | Waning Gibbous |  |
18 | None before about 9 pm, then High |
| First Quarter |  |
7 | Moderate, then none after midnight | Last Quarter |  |
22 | None until midnight, then Moderate |
| Waxing Gibbous |  |
11 | High until nearly dawn | Waning Crescent |  |
26 | None |
Return to Maine Nature News home page.
rev. 08/19/2006
