The Orionids at their peak

The following sun and moon data for Oct. 16, 2008 is provided by the United States Naval Observatory.

Sunrise: 7:17 a.m.

Sunset: 6:29 p.m.

Moonrise: 7:30 p.m.

Moonset: 10:50 a.m.

Moon phase: The moon is waning gibbous with 95 percent of the visible disk illuminated.

The Orionid meteor shower will light up the sky over Pagosa Country Tuesday just before dawn, however, bright moonlight will likely obscure all but the brightest meteors.

The Orionid peak is slated for Tuesday between 1 a.m. and dawn, although skywatchers should see random Orionids streaking across the sky Monday, Tuesday and Wednesday mornings.

Under prime, dark sky conditions, skywatchers would typically enjoy about 20 Orionids per hour; however that number may be reduced to single digits considering a large gibbous moon will be hovering overhead.

Despite the interference of moonlight, some Orionids will remain visible, as the Orionids are some of the fastest traveling and most showy of all the meteor showers. In fact, professional astronomical observations indicate the Orionids rip through Earth’s atmosphere at 41 miles per second, and the intense speed guarantees the Orionids vaporize, often leaving trails of colorful ionized gas that last a few seconds after the meteor is gone. Observations indicate about half of all Orionids result in the fireball effect, and the phenomena is likely the source for the colloquial reference to meteors as “shooting stars.”

Although meteors are heralded for their brilliant, shooting star-like displays, astronomers know meteors aren’t stars at all, but are bits of rock and ice shed as a comet hurtles through space. In the case of the Orionids, the particles were shed by Halley’s Comet during its passage through our solar system and whose orbital path Earth crosses during its own orbit around the sun. When the Earth passes through a comet’s debris trail, a meteor shower is born.

Meteor showers get their name from their apparent point of origin in our night sky. The point of origin is called the shower’s radiant. In the case of the Orionids, the meteors appear to emanate from the constellation Orion the hunter, hence the shower’s name.

Knowing a shower’s radiant is not necessary to enjoy the Orionids or any other meteor shower. The key is to find a dark sky location with clothing and other gear necessary to remain comfortable for weather conditions.

Earth’s yearly passage through the debris trail left by Halley’s Comet guarantees the Orionids will remain an annual event for years to come. However, stargazers will have to wait 53 years to view the meteor shower’s source. Halley’s Comet last appeared in the inner solar system in 1986, and will next appear in mid 2061.

james@pagosasun.com