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Tuesday, November 28, 2017


Geminid Meteor Shower 14-15 December 2017

The northern horizon at 4:00 am ACDST as seen from Adelaide on Thursday December 14. The Geminid radiant is marked with a starburst. Similar views will be seen elsewhere in Australia at  a similar latitude and the equivalent local time. (click to embiggen).The northern horizon at 3:00 am AEDST as seen from Sydney on Thursday December 14. The Geminid radiant is marked with a starburst. Similar views will be seen elsewhere in Australia at  a similar latitude and the equivalent local time. (click to embiggen).

The Geminids are unusual meteor shower in that their parent body is 3200 Phaethon, an asteroid, rather than a comet. It is speculated though that Phaeton is actually a "gassed out" comet, and so the debris that makes up the Geminids may still be cometary particles.
The Geminids are a fairly reliable meteor shower and this year moonlight will not interfere. Some decent meteors rates should be seen. 

Unlike the Leonids, where there is a very narrow peak of high activity, the Geminids have a broad peak and will show good activity well before and after the peak, and on the day before and after. The peak is December 14, 06h30m UT. That is 5 pm AEDST December 14 in Australia.  This is in daylight in Australia, but levels should remain good in the early morning so you should get decent rates. However, the radiant doesn't rise until just before midnight (daylight saving time) in most of Australia, so you will still have to disturb your sleep for this one. 

Australians should see a meteor every two to three minutes under dark skies in the early morning of the 14th, between 1:00 am and 4:00 am local daylight saving time. You can find predictions for your local site at the meteor flux estimator (choose 4 Geminids and date 14-15 December, don't forget to change the date to 2017). I have alos made a table for major citiess below.

Unfortunately, both Chrome and Firefox have changed their security settings to prevent plugins from running, and the flux estimator only runs under Internet Explorer now.
You can follow the progress of the shower at the IMO Geminids Live page.

At 1.00 am in the morning AEDST (midnight, AEST) Castor (alpha Geminorum) is about two hand-spans above the horizon and 10 hand-spans to the right of due north. Pollux, the other twin, is less than a hand-span to the right again. The radiant is just below Pollux.

When you get up, allow at least 5 minutes for your eyes to adjust and become dark adapted (even if you have stumbled out of bed in the dark, here's some hints on dark adaption of your eyes so you can see meteors better) and be patient, it may be several minutes before you are rewarded with you first meteor, then a couple will come along in quick succession (a meteor every three minutes is an average, they won't turn up like a ticking clock but more or less randomly).

Predicted meteor rates for selected towns

TownMorning December 13 Morning December 14Morning December 15
Adelaide9 meteors/hr22 meteors/hr15 meteors/hr
Brisbane11 meteors/hr27 meteors/hr21 meteors/hr
Darwin16 meteors/hr41 meteors/hr27 meteors/hr
Perth11 meteors/hr26 meteors/hr15 meteors/hr
Melbourne8 meteors/hr19 meteors/hr13 meteors/hr
Hobart6 meteors/hr14 meteors/hr10 meteors/hr

Choose a viewing spot where you can see a large swathe of sky without trees or buildings getting in the way, or with street lights getting in your eyes. The darker the spot the better (but do be sensible, don't choose a spot in an insalubrious park for example). While the radiant is where the meteors appear to originate from, most of the meteors will be seen away from the radiant, so don't fixate on the radiant, but keep your eye on a broad swath of sky roughly centred just above the radiant (as the radiant doesn't rise very high, looking exactly at the radiant will mean you miss some higher up).

A lawn chair or something similar will make your observing comfortable (or a picnic rug spread on the ground and a nice pillow), and having a Thermos of hot coffee, tea or chocolate to swig while watching will increase your comfort. Despite it being summer, make sure you have a jumper or something as the night can still get cold

Guides to taking meteor photos are here and here.

As well, Orion and the Hyades will be visible and bright Jupiter (and less bright Mars) will be nearby, rising an hour before sunrise. So it will be a quite nice morning for sky watching. Keep an eye out for satellites!

Cloud cover predictions can be found at SkippySky.  

Here is the near-real time satellite view of the clouds (day and night) http://satview.bom.gov.au/


Geminid meteor is my favorite meteor shower and I am so happy that I am luck enough to see it. Your article was very helpful and informative thanks for posting https://goo.gl/FmVjJr
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