The Planet Jupiter gleams high in the southern sky after dark during the entire month of October. Jupiter's Galilean satellites, the four largest and brightest moons circling the planet, can be easily observed this month using equipment as simple as firmly supported, high-power binoculars. First noted by Galileo in 1609, these satellites noticeably change their configuration from night to night as they swing around the planet.
Low-Lying Temperature Inversions commonly occur in San Diego from late fall through early winter. During the night and morning hours, a meterological condition often occurs in which the "normal" higher-you-go-the colder-it-gets trend is reversed. At such times cold marine air lies below a stable layer of warmer air originating from inland locales. Whenever moist air is trapped below a low-lying inversion layer, dense fog forms on or near the ground, and San Diego International Airport may be forced to suspend operations.
The Floss Silk Tree, a conspicuous "autumn bloomer" here and there around San Diego has been showing off its pinkish or purplish, hibiscus-like flowers for at least a month now. The broad, heavy trunks of this South American import, studded with fat, cone-shaped spines makes it easy to identify.
Autumn Color in San Diego County's mountains reaches its greatest intensity in late October and early November. The forested heights of Palomar Mountain are especially colorful right now. Black oaks on Palomar's rolling uplands will be exhibiting bright yellow and brown hues for the next few weeks. Cuyamaca Reservoir, although hit hard by the 2003 Cedar Fire, remains a worthwhile leaf-peeping destination. The shimmering leaves of the Lombardy poplar, an Italian import that has taken root at the south end of the lake, delight the eye with their golden radiance.