Monarch Butterflies Arrive Along The California Coast this month, migrating from their summer homes in the Sierra Nevada and the Rocky Mountains. Some 25 of their 260 wintering sites on the West Coast lie within San Diego County. The local sites include Presidio Park in San Diego, the UCSD campus, Quail Botanical Gardens in Encinitas, and Hosp Grove in Carlsbad.

Our Earliest Sunset (4:42 p.m. from San Diego) Occurs Monday, December 3 or 4, a date that is not coincident with the shortest day (winter solstice – December 21) because of factors relating to the non-circular shape of Earth’s orbit around the sun and the tilt of Earth’s rotational axis. Because of the elliptical orbit of the earth, when the earth is closer to the sun, its orbit is quicker. Because of the rotational axis of the earth, a solstice occurs when one of the poles is leaning towards the sun, while an equinox occurs when neither pole is leaning towards the sun. Our clocks are set so that every day is exactly 86,400 seconds, but in reality, the solar day can be up to 22 seconds shorter or 29 seconds longer than 24 hours. Early December is a good time to view the setting sun from the spectacular vantage point of Cabrillo National Monument at the tip of Point Loma. (During most of the year, you can’t do that, since sunset occurs well after the park’s closing time of 5 pm.)

The Moon’s Cheshire-cat Smile Returns to the evening sky Tuesday evening, November 25. You’ll spot its very thin crescent shape low in the southwest about one half hour after sunset. On succeeding evenings observe the moon’s thickening crescent and its increased prominence in the early evening sky.
Monarch Butterflies Arrive Along The California Coast this month, migrating from their summer homes in the Sierra Nevada and the Rocky Mountains. Some 25 of their 260 wintering sites on the West Coast lie within San Diego County. The local sites include Presidio Park in San Diego, the UCSD campus, Quail Botanical Gardens in Encinitas, and Hosp Grove in Carlsbad.

Our Earliest Sunset (4:42 p.m. from San Diego) Occurs Monday, December 3 or 4, a date that is not coincident with the shortest day (winter solstice – December 21) because of factors relating to the non-circular shape of Earth’s orbit around the sun and the tilt of Earth’s rotational axis. Because of the elliptical orbit of the earth, when the earth is closer to the sun, its orbit is quicker. Because of the rotational axis of the earth, a solstice occurs when one of the poles is leaning towards the sun, while an equinox occurs when neither pole is leaning towards the sun. Our clocks are set so that every day is exactly 86,400 seconds, but in reality, the solar day can be up to 22 seconds shorter or 29 seconds longer than 24 hours. Early December is a good time to view the setting sun from the spectacular vantage point of Cabrillo National Monument at the tip of Point Loma. (During most of the year, you can’t do that, since sunset occurs well after the park’s closing time of 5 pm.)

The Moon’s Cheshire-cat Smile Returns to the evening sky Tuesday evening, November 25. You’ll spot its very thin crescent shape low in the southwest about one half hour after sunset. On succeeding evenings observe the moon’s thickening crescent and its increased prominence in the early evening sky.
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