ALPO Meteors Section

Coordinator: Robert Lunsford

The peak of the 1998 Leonid meteor shower (rich in bright fireballs), shown in a four-hour time exposure through a fisheye lens, and taken by Juraj Toth of Modra Observatory. This photograph demonstrates how the meteors in a particular shower appear to emanate from a certain point in the sky called the radiant. On a given night, this radiant point will remain relatively stationary with respect to the background star constellations; but will rise, traverse the sky, and set in the same manner as the sun and moon.

Viewing Meteor Activity

Since meteors are a transient phenomena one cannot go outside at night and expect to see meteor activity. This is especially true during the evening hours when the Earth is moving in the opposite direction from the sky seen above during those hours. At this time of night meteoroids (meteors in space) must catch up to the Earth in order to enter the Earth’s atmosphere. Therefore meteor rates are lowest near 1800 (6:00pm) local time. Conditions for viewing meteor activity improves as the night progresses. At midnight a great majority of the meteors seen strike the Earth from a perpendicular angle instead of from behind. These conditions offer better rates than witnessed early in the evening but the general activity is still low when compared to the morning hours. During the dark morning hours the Earth is rotating toward the direction it moves in space, known as the apex. During this time the Earth slams head-on into meteoroids and many more will be seen. This is much like a vehicle driving through the rain. More raindrops will strike the front windshield compared to the rear window. The peak meteor activity occurs near 0600 local time.

In addition to the diurnal cycle there are also annual variations in the meteor activity. As seen from the mid-northern hemisphere the second half of the year is much more active than the first six months. The reason for this are several. First of all the sporadic (random) meteor activity is stronger during this period. Also most of the major annual showers active during the second half of the year have radiants located north of the celestial equator, favoring northern observers. The cycle seen from the mid-southern hemisphere is opposite with the better activity occurring during the first half of the year. Observers at the equator enjoy fair, but not exceptional activity all year long.

During certain times of the year the major meteor showers are active and increase the nightly activity several fold. This is especially true if the moon is near its new phase and not brightening the nighttime sky. The list of these showers is provided below (see the class I showers).

This is also the best time to see fireballs, which are exceptionally bright meteors that can light the nighttime scene. These meteors can range from the light of the brightest planet Venus (magnitude -5) to that beyond the light produced by the full moon (magnitude >-13).

This double bursting fireball was photographed at 23:45 Universal Time on August 6, 2007 by Maurizio Eltri from central Venice, Italy. He estimated this sporadic (random) fireball to be of maximum magnitude -8, which is nearly as bright as the half moon. Picture courtesy of Maurizio Eltri, (Unione Astrofili Italiani Sezione Meteore).

To keep current on the upcoming meteor activity the Meteors Section invites you to subscribe to their quarterly newsletter, available for the price of postage (currently 55 cents per issue). To subscribe contact our section coordinator Robert Lunsford.

The 2021 Meteor Shower List is presented in four separate parts. The showers are broken down by intensity with major, minor, variable, and weak showers being separated into their own groups. The general public is encouraged to use the list of major showers as they are the most well known and provide the most activity on a year to year basis. The other showers rarely surpass ten meteors per hour at maximum and are difficult to observe by the general public.

                                                         2021 Major Meteor Showers (Class I)

Information and Table Template Courtesy the International Meteor Organization and Masahiro Koseki.

The meteor showers listed above are the easiest to observe and provide the most activity. Particular attention should be noted to the time and moonlight conditions. All these showers are best seen after midnight. Some are not even visible until after midnight. Showers that peak with the moon’s age between 10 and 20 days will be affected by moonlight and difficult to observe this year. While the time each shower is best seen remains much the same year after year, the moonlight conditions change considerably from one year to the next. We will post upcoming details of each major shower that is free from moonlight well in advance of their peak activity.

                                                         2021 Minor Meteor Showers (Class II)

Information and Table Template Courtesy the International Meteor Organization and Masahiro Koseki.

The meteor showers listed above range from 2 to 10 shower members per hour at maximum activity. These meteors can be detected by experienced observers but novice observers and the general public will have difficultly distinguishing these meteors from the major showers or sporadic (random) meteors.

                                                      2021 Variable Meteor Showers (Class III)

Information and Table Template Courtesy the International Meteor Organization.

The meteor showers listed above produce strong activity on rare occasions. Most of the time only a few scattered remnants of these showers are observed with rates of one shower member per NIGHT. Note that most of these showers are best seen during the evening hours, a situation quite opposite most meteor showers.

                                                          2021 Weak Meteor Showers (Class IV)

The focus of this book is to introduce the novice to the art of meteor observing. It explains in straightforward language how best to view meteor activity under a variety of conditions, regardless of the observer’s location. The observing conditions for each meteor shower are vastly different from each of the Earth’s regions and this book would be valuable to any potential observer from Australia to Alaska. The calendar chapters list activity as it occurs throughout the year. The list is limited to showers that the amateur observer can actually see (some sources list radiants that are impossible to observe without photographic or video methods). Not only are the annual showers discussed, but the random sporadic meteor activity is also included for each region. This is important, as there are many more nights throughout the year when the sporadic background will provide more activity than that provided by the annual showers!…more on
http://springer.com/978-0-387-09460-1