Geminids and Gibbous Moons

When the Geminid meteor shower peaks on Dec. 13 and 14, a pesky, almost full moon is poised to steal fireball thunder. The annual Geminids are one of the most prolific night shows, with an average of 120 meteors an hour. As if losing ISON wasn’t bad enough; a bright winter moon is expected to reduce visible meteors 2 – 5 fold.

Annual meteor showers result from earth’s orbit intersecting debris from a sun orbiting comet. Radiant point, is the name given to this intersection. Debris from comet 3200 Phaethon happens to intersect our orbit in the vicinity of constellation Gemini, hence – Geminids. To find Gemini, look for the star Castor, low on the east, north-east sky around 9 PM. Castor is one of the brightest stars in the sky and along with Pollux, make up the ” twin brothers ” of Gemini. The reason Geminids produce so many visible meteors is that the constellation and radiant point swing upward; by 2 AM the point is directly above you in the sky. The angle of the radiant, translates into no poor seats for this show – you can see it from anywhere, with 2 AM as your prime time.

This year we have a waxing gibbous moon to deal with – not a deal breaker, but grounds for some new rules. Since the nearly full moon is so bright, you should wait until the moon sets. This year pre-dawn moon set offers the best view. Get out of town – away from city lights – and give yourself a few minutes to adjust to the darkness. Gibbous moon aside – I guarantee you’ll see fireballs – you don’t even have to find Gemini, the Geminids have a crazy way of appearing to come from any direction.

http://earthsky.org/astronomy-essentials/radiant-point-for-geminid-meteor-shower

To find out when the moon sets in your little corner of the world – a link…..

http://www.usno.navy.mil/USNO/astronomical-applications/data-services

Ponder the last time you wished upon a falling star.

Jupiter, Castor and Pollux rise at early-to-mid evening in early December but at dusk or nightfall  by the month's end.

Jupiter, Castor and Pollux rise at early-to-mid evening in early December but at dusk or nightfall by the month’s end.

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