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 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.
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 >>> http://meteorshowersonline.com/showers/draconids.html
Link 2 >>> https://en.wikipedia.org/wiki/Draconids
More about Constellation Draco the Dragon ---
Link 1 >>> http://www.astro.wisc.edu/~dolan/constellations/constellations/Draco.html
Link 2 >>> https://en.wikipedia.org/wiki/Draco_%28constellation%29
Related Blog Posts ---
"2011 Meteor Shower Deposits Ton of Material On Earth." 2013 June 10.
Link >>> http://spacewatchtower.blogspot.com/2013/06/2011-meteor-shower-deposits-ton-of.html
"Tonight: Unpredictable Draconid Meteor Shower Peaks." 2012 Oct. 7.
Link >>> http://spacewatchtower.blogspot.com/2012/10/tonight-unpredictable-draconid-meteor.html
Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
Want to receive SpaceWatchtower blog posts in your inbox ?
Send request to < spacewatchtower@planetarium.cc >..
gaw
Glenn A. Walsh, Project Director,
Friends of the Zeiss < http://buhlplanetarium.tripod.com/fotz/ >
Electronic Mail - < gawalsh@planetarium.cc >
SpaceWatchtower Blog: < http://spacewatchtower.blogspot.com/ >
Also see: South Hills Backyard Astronomers Blog: < http://shbastronomers.blogspot.com/ >
Barnestormin: Writing, Essays, Pgh. News, & More: < http://www.barnestormin.blogspot.com/ >
About the SpaceWatchtower Editor / Author: < http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/ >
SPACE & SCIENCE NEWS, ASTRONOMICAL CALENDAR:
< http://buhlplanetarium.tripod.
Twitter: < https://twitter.com/spacewatchtower >
Facebook: < http://www.facebook.com/pages/
Author of History Web Sites on the Internet --
* Buhl Planetarium, Pittsburgh:
< http://www.planetarium.
* Adler Planetarium, Chicago:
< http://adlerplanetarium.
* Astronomer, Educator, Optician John A. Brashear:
< http://johnbrashear.tripod.com >
* Andrew Carnegie & Carnegie Libraries:
< http://www.andrewcarnegie.
* Civil War Museum of Andrew Carnegie Free Library:
< http://garespypost.tripod.com >
* Duquesne Incline cable-car railway, Pittsburgh:
< http://inclinedplane.tripod.
* Public Transit:
< http://andrewcarnegie2.tripod.
No comments:
Post a Comment