Across the Universe

December hosts one of the most famous meteor showers of the year: the Geminids. The Geminid meteor shower is a long meteor shower with the possibility of seeing an increase in meteor activity from Dec. 4 through 17, peaking Dec. 13 to 15. The moon phase on the peak dates — a thin, waxing crescent setting in the early evening — is ideal for meteor watching. It is estimated that up to 100 meteors per hour could be visible during this year’s peak.

A meteor, commonly called a “shooting star,” is a rock from space that enters the Earth’s atmosphere. As the rock falls through the Earth’s atmosphere, it heats and glows creating a fiery streak visible to those on the Earth’s surface. Smaller meteors fall apart upon entry, but larger meteors can crash onto the surface. Once on the Earth, the meteor becomes a meteorite.

The names of space rocks change depending on their locations. Asteroids are rocks in space, meteors are rocks from space actively falling to the Earth. and meteorites are rocks from space sitting on the Earth.

Meteors can be visible any night, but several times per year the Earth passes through the debris of old comets or asteroids causing increased meteor activity. These periods are known as meteor showers. The showers derive their names from the constellation that the meteors seem to originate. The Geminids appear to come from the constellation Gemini. As the night progresses and Gemini rises higher in the sky, the frequency of the shower will increase.

The Geminids have nothing to do with the constellation Gemini. Every Dec., the Earth crosses the orbit of the asteroid 3200 Phaethon. 3200 Phaethon has a highly elliptical or elongated orbit. At times, its orbit takes the asteroid closer to the sun than Mercury. Other times it orbits past Mars. As it closely approaches, the gravity of the sun causes 3200 Phaethon to crumble a bit, leaving debris littering the asteroid’s orbit. As the Earth passes through these debris fields, the crumbled fragments fall to the Earth’s surface.

To watch the Geminids, you only need your eyes and a dark location. The constellation Gemini is relatively easy to locate. It lies near the famous constellation of Orion the Hunter. While the meteors appear to originate from Gemini, it is not necessary to know the location of the constellation to see meteors. Meteors often arrive in spurts after a lull. Be patient and allow your eyes at least 20 minutes to adjust.

For more information on the Geminids or any topic in astronomy, come to the Canada-France-Hawaii Telescope’s Winter Star Party on Saturday, Dec. 5 from 7 to 10 p.m., immediately following the Waimea Christmas Parade. We will have telescopes set up on our front lawn, refreshments, keiki activities, an “Ask an Astronomer” booth and a peak into our remote observing room. The star party is free of charge and open to everyone. For more information, call 885-3121.