[BAA-ebulletin 00827] Geminid Meteor Shower Underway

[Rick]

[BAA-ebulletin 00827] Geminid Meteor Shower Underway
(c) 2014 British Astronomical Association    http://www.britastro.org/

The Geminid meteor shower is now underway, with peak activity expected throughout the coming weekend.. 

The Geminids are the richest of the annual meteor showers, with rates outstripping those of the Perseids for a 24-hour interval centred on their 14 December maximum. The peak this year coincides with a last quarter Moon in Virgo, so there should be comparatively little interference by moonlight even during the early morning hours. The highest observed rates are most likely during the night of December 13/14, particularly in the pre-dawn hours of Sunday, December 14, and conveniently during a weekend.

This year, Geminid maximum is expected at around 07h on Sunday, 14th December, when the peak Geminid Zenithal Hourly Rate may reach 120 m/h. There is the added bonus of an increased proportional abundance of bright events after maximum; past observations show that bright Geminids become more numerous some hours after the rates have peaked, a consequence of particle-sorting in the meteor stream.

The Geminid maximum is quite broad so it is important to have a spread of observers making observations throughout the nights of 12th/13th, 13th/14th and on 14th/15th December to ensure adequate coverage of the shower maximum. In addition, observations by BAA members in North America and the Far East will be welcomed by the Meteor Section to improve coverage of the period of peak shower activity.

The Geminid radiant (at RA 07h 32m  Dec +33o, just north of Castor) rises early in the evening and reaches a respectable altitude well before midnight, so observers who are unable to stay up late can still contribute useful watches.

Meteor showers are supposed to come from periodic comets, yet there is no very short period comet that matches the orbit of the Geminid meteoroid stream. Instead, the orbit of the Geminids is occupied by an object called 3200 Phaethon, which looks remarkably like a rocky asteroid. A group of astronomers led by David Jewitt of UCLA have been using NASA's STEREO probes to take a closer look at 3200 Phaethon when it passes closest to the Sun. In 2010 one of the STEREO probes recorded a doubling of Phaethon's brightness as it approached the Sun, as if sunlight were shining through a cloud of dust around the asteroid.

The observers began to suspect 3200 Phaethon was something new - a "rock comet" which is, essentially, an asteroid that approaches so close to the Sun that solar heating scorches dusty debris right off its rocky surface forming a tail of rocky grains. Seeing 3200 Phaethon sprout a tail, even a small one, provides some confidence that Phaethon is indeed the source of the Geminids - but a mystery remains: How can such a stubby protuberance produce such a grand meteor shower? Only time and further continued observations may provide the answer.

Geminid meteors enter the atmosphere at a relatively slow 35 km/sec, and thanks to their robust (rocky/asteroidal as opposed to dusty/cometary) nature tend to last longer than most in luminous flight. Unlike swift Perseid or Orionid meteors, which last only a few tenths of a second, Geminids may be visible for a second or longer, sometimes appearing to fragment into a train of 'blobs'. Their relatively low speed and the abundance of bright events makes the Geminids a prime target for imaging.

For further information, or copies of report forms, observing notes, and details of how to carry out group meteor watches, please visit the BAA Meteor Section website at http://britastro.org/meteor

This e-bulletin issued by:
John W. Mason, Director, BAA Meteor Section
2014 December 10

[Rick]

[BAA-ebulletin 00828] Live observations of Geminid meteors on the BAA website
(c) 2014 British Astronomical Association    http://www.britastro.org/

This weekend will be the highlight of the meteor observing year, with the Geminid meteor shower reaching its peak in the early hours of Sunday morning. You can find details of how to observe the shower in the eBulletin that John Mason circulated yesterday.

To help as many people as possible to see the meteors, we are also running an online observing event on the BAA website, which you can find here: http://britastro.org/2014geminids . We are posting images recorded by two upward-pointing CCTV cameras operated by Nick James in Chelmsford.

Nick's cameras automatically take images whenever they detect movement in the sky, and the images are posted to the BAA website almost immediately. In the past couple of nights, they have already recorded more than a dozen meteors, and we hope they will record many more over the weekend.

The automated nature of these cameras means that in addition to meteors, they also detect many planes, birds, clouds, especially in the early evening. If you have an account on the BAA website (which you can set up by visiting http://www.britastro.org/user/register ), you can submit votes for which images you think are of genuine meteors, and which you think bogus. You can also see what other users think.

This is, of course, no substitute for going out, doing your own meteor watches and submitting your results to the Meteor Section. See http://britastro.org/article_render/5885 for more information about how to do that. However, our online event will hopefully prove a fun way for you to see some of the very fine images being produced by video cameras operated by Meteor Section members in the NEMETODE network.

Clear skies!

Dr Dominic Ford
BAA Website Manager

[Kenny]

Tweet #meteorwatch (your location in brackets) and how many meteors seen to have them plotted on the meteor map.
http://www.meteorwatch.org/meteor-map.html

[Mike]

The forecast for tonight and the morning is looking perfect for this. Best time to see them will be in the early hours of tomorrow morning.

Set your alarms and charge your camera batteries.

Mike

[MarkS]

The forecast for tonight and the morning is looking perfect for this. Best time to see them will be in the early hours of tomorrow morning.

But remember the moon rises at 00:30 so the early hours will be moonlit ...