Jumpin' Geminids

What you’ll see: You might see a meteor per minute. (Maybe more, maybe less. And the darker the sky conditions, the better!)

When to look: Here in North America, the best time for viewing will be the evening of Thursday, December 13 (with the meteor rate increasing as the night goes on) and somewhat also the evening of Friday, December 14 (declining as the night goes on).

Where to look: Looking toward the constellation Gemini (near Orion and Taurus) will increase your chances of seeing meteors, but it’s possible to see them anywhere in the sky. (See below for more about this.)

**Be sure to allow about 20 minutes in the dark in order for your eyes to adapt! And don’t forget to dress warmly to ensure a comfortable observing session.

(Click on the above Stellarium freeze-frame for an enlarged view.)

All About Meteor Showers:

◦ A meteor is a brief, one to two second streak of light across the sky. Although sometimes referred to as a “shooting star” or “falling star”, a meteor is not a star at all but actually a small rock being heated and vaporized as it descends through the Earth’s atmosphere. (Note that meteors are sometimes also confused with comets. Unlike meteors, comets are chunks of rock and ice in orbit around the Sun, usually with a “tail” and, when visible from Earth, seen in approximately the same position in the sky over the course of several days or weeks.)

◦ In recent years, scientists have discovered that most meteors are surprisingly small—the average bright meteor streak is caused by a rock no bigger than a pencil eraser in diameter!

◦ On any given night of stargazing, you can expect to see a meteor or two. (The rate on an average night is about 2 meteors per hour.) This is because, at any given time, there are always a few small rocks that happen to wander too close to the Earth, and are pulled in by our planet’s gravity.

◦ A meteor shower, or large increase in the hourly meteor rate, occurs when the Earth makes an annual pass through a stream of small rocky debris left by various small rocky objects in our solar system (e.g. comets and asteroids). Typically the best meteor showers are the Perseids (mid-August, when we pass through the debris stream left by Comet Swift-Tuttle) and the Geminids (mid-December, when we pass through the debris stream left by an asteroid called Phaethon), though there are eight other major annual meteor showers. (Usually these latter are somewhat less impressive).

◦ During the Geminid meteor shower, it may be possible to see meteors at any place in the sky, however it’s best to look in the general vicinity of the constellation Gemini. (See the attached star chart; Gemini is to “upper left” of Orion; located 30 to 40° above the eastern horizon by 9:00 pm.)

◦ The “debris streams” mentioned above tend to intersect the Earth at a single point. As a result, during a meteor shower we see a perspective effect, whereby all of the meteors of a given shower appear to radiate, like spokes on a wheel, from one place in the sky. This explains our naming system for meteor showers: the Geminid meteor shower appears to radiate from the constellation Gemini; the Perseids from the constellation Perseus, etc.

(Hat tip for the title "Jumpin' Geminids": Gus Van Horn.)