Steamboat Pilot & Today

Jimmy Westlake

Jimmy Westlake's Celestial News column appears Tuesdays in the Steamboat Today.

Find more columns by Westlake here.

If you've noticed an increase in the number of shooting stars in recent nights, there's good reason. This month's annual Delta Aquarid meteor shower is increasing in activity as we get closer to its peak in the morning July 29. Other minor showers, such as the Kappa Cygnids and the Capricornids, also are throwing in a few meteors.

A meteor shower is named for the constellation from which the meteors seem to radiate, so we have, for example, the August Perseids, which radiate from the constellation of Perseus; the December Geminids, which radiate from the constellation Gemini; and this month's Delta Aquarids, which seem to spring from near the star Delta in the constellation Aquarius.

Our annual meteor showers are produced when the Earth plows through the path of an old comet and collides with leftover dust particles in the comet's wake. The parent comets for most of our major annual meteor showers have been well established. For example, the May Aquarids and the October Orionids are produced when Earth crosses the orbit of Halley's Comet, twice each year. July's Delta Aquarid shower is unique in that it is the only strong shower whose parent comet is unknown. Either the parent comet was pulled into a different orbit long ago after a close pass by one of the outer planets, or it met with some catastrophic end. The primary suspect is periodic comet 96P/Machholz 2, which crumbled into pieces as astronomers watched it round the sun in 1994. But this conclusion is far from certain. For the present time, the source of the July Delta Aquarid meteors remains a mystery.

To watch the Delta Aquarid meteor shower, you'll need to set your alarm for about 3 a.m. July 29, or else (like me) just stay up all night long. The constellation of Aquarius doesn't rise until about 11 p.m. Tuesday, so, don't expect to see any Delta Aquarids before then. Aquarius is at its highest in the southern sky about 4 a.m., so this will be the best time to watch. The meteors will seem to dart in every direction, but their paths will start from near the star Delta Aquarii, just above the bright star Fomalhaut. You might see about one or two shower meteors every five minutes, on average. It's more of a sprinkle than a shower, really. Consider the Delta Aquarids just a warm-up for the granddaddy of all meteor showers, the August Perseids, which can produce more than one meteor per minute.

Professor Jimmy Westlake teaches astronomy and physics at Colorado Mountain College's Alpine Campus. He is an avid astronomer whose photographs and articles have been published around the world. His "Celestial News" column appears weekly in the Steamboat Pilot & Today newspaper and his "Cosmic Moment" radio spots can be heard on local radio station KFMU. Also, check out Jimmy's astrophotography Web site at www.jwestlake.com.