This week marks the peak of the Geminid meteor shower, usually one of the most satisfying of all annual meteor events.

But, like what happened last month with the Leonid meteor shower, prospective skywatchers will face a major obstacle in their efforts to see this year's Geminid performance -- the moon, which turns full on Dec. 17, and will seriously hamper viewing the Geminids peak, predicted in the overnight hours of Dec. 13-14.

Astronomers warn bright moonlight will flood the sky through much of that night, washing out at least some of the otherwise spectacular meteor shower.

The Geminids actually are already visible in the sky, though very weak and scattered since about Dec. 7. The related meteor activity is expected to increase in the nights to come, leading up to their peak on Friday night, Dec. 13.

The shower historically has a reputation for containing slow, bright, meteors, in addition to rather faint ones, with relatively few in the medium range.

Many of the Geminid meteor shower streaks appear yellowish in hue and every now and then a Geminid fireball will blaze bright enough to attract lots of attention, even in bright moonlight.

"If you have not yet seen a mighty Geminid fireball arcing gracefully across an expanse of sky, then you have not seen a meteor," wrote astronomers David Levy and Stephen Edberg in their book, Observe Meteors, published by the Astronomical League.

So, the best times this year to look for streaking Geminids will be during the predawn hours several mornings before the night of full moon, when the constellation Gemini will be positioned high in the northwest sky.

Three "windows" of dark skies will be available between moonset and dawn's first light on the mornings of Dec. 13, 14 and 15. There will be about two hours of completely dark skies on the morning of Dec. 13; however, that window of darkness will shrink to only about an hour on the 14th and less than 10 minutes by the morning of the 15th.

The day before they peak, the majority of Geminids seen are usually rather faint. At their peak, as well as the day after, the shower is dominated by large number of bright meteors. The intensity of the display drops off rather sharply a day after the peak.

That means if you're at a location free from light pollution and with a wide-open view of the sky the two-hour period of dark skies on the morning of Friday, the 13th, you should expect to see an average of 30 to 60 Geminids per hour, though many will probably be rather faint.

The shower peaks on Saturday morning.