Monday, October 5, 2015

Unpredictable Draconid Meteor Shower Peaks Thursday

Constellation Draco the Dragon, the apparent
radiant from where Draconid meteors emanate
(Image Source: University of Wisconsin).

By Glenn A. Walsh
Reporting for SpaceWatchtower

A usually very modest, but also very unpredictable, meteor shower, which at some times in the past has created a meteor storm, peaks this week. The Draconid Meteor Shower, sometimes referred to as the Giacobinid Meteor Shower, peaks Thursday (2015 October 8) at 4:00 p.m. Eastern Daylight Saving Time (EDT) / 20:00 Coordinated Universal Time (UTC). Of course, meteors would not be visible until after local sunset.

This meteor shower can usually be seen between October 6 and 10, with the peak occurring October 8 and 9. Although in most years only 1-to-2 meteors may visible per hour near the peak.

However, there have been major exceptions to this low meteor rate, in the past. The Draconid Meteor Showers of 1933 and 1946 had Zenithal Hourly Rates of thousands of meteors per hour. These were among the most impressive meteor storms of the 20th century.

Other impressive outbursts of this meteor shower occurred with a sudden spike in 1998 and a less spectacular spike in 2005. An expected outburst did occur in 2011 (which included more than 400 meteors per hour), one of the most intense meteor showers of the decade. However the brightness from a waxing gibbous Moon reduced the number of meteors actually seen in 2011.

Up to 1000 meteors per hour were detected by radar observations of the 2012 outburst. It is speculated that this particular outburst may have been caused by a narrow trail of dust and debris left by the parent comet in 1959.

A meteor shower normally consists of dust particles related to a comet. Each time a comet approaches the Sun, the comet loses dust particles following the melting of ice on the comet. These dust particles, called meteoroids, continue to follow the same orbit as the comet and form a meteoroid stream. Each year, as the Earth orbits the Sun, the Earth passes through several of these meteoroid streams, becoming Earth's meteor showers.

The Earth's gravity then attracts many of these meteoroids to fall to Earth, and they are viewed by people as meteors, as they burn-up in the atmosphere. Most are extremely small and burn-up completely. From time-to-time, larger particles enter the atmosphere and create brilliant displays known as fireballs. If these particles are large enough, they may not completely burn-up and land on Earth as a meteorite.

The parent comet of this particular meteor shower is Comet 21P / Giacobini-Zinner, hence the reason some call these meteors Giacobinids. These meteors are better known as Draconids, as they appear to come from the Constellation Draco the Dragon.

This meteor shower was predicted by several astronomers in the early part of the 20th century. M. Davidson was the first to make such a prediction in 1915, after evaluating several comets capable of producing meteor showers. W.F. Denning became the first person to observe meteors that may have come from such a new meteor shower during the first half of October in 1915. After Davidson revised his prediction in 1920 (primarily due to a discovered, mathematical error in the original prediction), Denning made a conclusive observation of this new meteor shower, the meteors of which he described as “slow.”

To more easily see these meteors it is better to be away from city lights, as artificial lighting can drown-out the dimmer meteors. The best time to see any meteor shower is between local midnight and morning twilight, when the Earth is actually rotating-into the meteor shower. Of course meteor showers, like all celestial observations, are weather-permitting.

Binoculars and telescopes are not very useful for finding meteors. Meteors streak across the sky in a very short period of time, too short to aim binoculars or a telescope. So, the best way to view a meteor shower is to lie on the ground, in an area with a good view of the entire sky (with few obstructions such as buildings, trees, or hills), and keep scanning the entire sky.

Meteor showers appear to emanate from a radiant point in the sky. As previously mentioned, for the Draconid Meteor Shower, the radiant appears to be the Constellation Draco. However, you should not, necessarily, be looking only at Draco, when looking for meteors in this shower. Meteors can appear in any part of the sky at any time.

This week, a waning crescent Moon does not begin to rise until the early morning hours. So, moonlight should not be a major hindrance to viewing Draconids.

So, if you want to take a chance on this unpredictable meteor shower, start looking for meteors around local Midnight, or perhaps a little earlier. Make sure you have a good site where you can see most of the sky, and that sky is relatively clear. Be sure to dress properly for the Autumn, early morning temperatures.

And, you want to go out ahead of time, before you start actual viewing of meteors, to get your eyes accustomed to the dark sky. Dark-adapting your eyes for meteor watching could take up to a half-hour.

More about the Draconid Meteor Shower ---
Link 1 >>>
Link 2 >>>

More about Constellation Draco the Dragon ---
Link 1 >>>
Link 2 >>>

Related Blog Posts ---

"2011 Meteor Shower Deposits Ton of Material On Earth." 2013 June 10.

Link >>>

"Tonight: Unpredictable Draconid Meteor Shower Peaks." 2012 Oct. 7.

Link >>>

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.

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