Thunderheads, Sandpipers, Naked-Eye Planets, and the Perseid Meteor Shower

Towering thunderheads, various sandpipers, naked-eye planets, and the Perseid meteor shower

Towering thunderheads have been seen hovering over the wall of mountains east of San Diego in recent weeks. Afternoon rainshowers have already dampened Palomar, Cuyamaca and Mount Laguna on several occasions, with more of the same expected at times during the next two or three weeks. Usually this kind of activity ceases by sunset, and clearing skies usher in a cloud-free night. The marked contrast between the sunny, but bland weather along the coast and the more lively and unpredictable mountain weather is one illustration of San Diego County's "geography of contrast."

Various sandpipers are now being seen in considerable numbers within San Diego County's coastal wetland habitats and along the ocean beaches. Some have just arrived from the north; others are juveniles that have bred locally. You'll find sanderlings and willets scurrying along the wet sand on the beaches. Several other members of the sandpiper family can be found in mudflat areas such as the Tijuana River Estuary, the south end of San Diego Bay, the San Diego River flood channel near Sea World, and the margins of most North County lagoons.

All five "naked eye" planets can be glimpsed after dusk during much of the month of August. This week and next, for example, try to spot sparkling Venus low in the west about 1/2 hour after sunset. Mercury, Saturn and Mars can be spotted using binoculars in the areas to the lower right and the upper left of Venus. Opposite this group of four (eastward), Jupiter appears as steadily glowing, yellowish orb.

The Perseid meteor shower, the best known of the many meteor displays that return annually, peaks this year during the wee hours of Tuesday, August 12. The bright waxing gibbous moon will largely spoil the view until it sets at approximately 1:30 a.m. From that time until dawn's earliest light (4:40 a.m.) however, the combination of moonlight-free skies and the shower's peak overall activity will ensure hourly rates of 60 meteors or more. This rate assumes clear, dark skies, such as you would find in San Diego County's remote mountain and desert areas. Hourly rates will be perhaps half as much if you observe on the mornings of the 11th or the 13th. The Perseid meteors, like other similar annual meteor showers, occur when Earth plows through a broad stream of tiny dust particles left over from the past disintegration of a comet. The particles burn up as air friction slows them at heights of about 50 miles, resulting in luminous trails visible for a second or two from the ground. Following the passage of a particularly bright meteor a lingering glow, called a train, may remain for a few more seconds. For best viewing results, lie in a comfortable position, facing northeast. Don't forget your cup of strong coffee!

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