| The Magazine of the CALIFORNIA ACADEMY OF SCIENCES |
|
|
|
|
|
Skyguide October to December 2002 October 6 New Moon. The Moon lies in the same direction as the Sun in the sky and is hidden from view by the glare. It is also at this month’s perigee, or its closest point to Earth. The combination of perigee and New Moon can result in very high tides. October 8 The Draconid meteor shower, also known as the Gia cobinid shower, is usually a rather meager display, but has had some interesting outbursts since its parent comet returned in 1998. The waxing crescent Moon sets early in the evening, so its light will not interfere with later viewing. October 19 Moon at apogee, or farthest distance from Earth, at 31.8 times the Earth’s diameter. At perigee on October 6, the Moon was 28 Earth-diameters away. This change in distance results in a 14 percent variation in the Moon’s apparent diameter each month. October 20 Full Moon. Since this is the first to follow last month’s “Harvest Moon” this full moon was called the “Hunter’s Moon” by colonial settlers and the Algonquin. It has also been referred to as the “Ripe Corn Moon” by the Laguna and the “Leaf Fall Moon” by the San Juan. November 4 New Moon. The first possible sighting of the young crescent after sunset tomorrow will mark the start of Ramadan, the Muslim month of fasting. November 17 Peak of the Leonid meteor shower. This event has been quite spectacular in recent years, briefly reaching “storm” proportions (bursts of more than 1,000 meteors per hour). Some astronomers suggest that this year’s display may produce another storm—perhaps the last one for many years. Unfortunately, the bright light of a waxing gibbous Moon may hamper viewing. November 19 Full Moon against the stars of Taurus. Known to the Cheyenne as the “Freezing Moon” and to the Algonquin as the “Beaver Moon.” December 3 As the New Moon passes between Earth and the Sun, a total solar eclipse is visible across southern Africa, the southern Indian Ocean, and southern Australia. Most of Africa, Madagascar, part of Antarctica, and western Australia will see at least a partial eclipse. December 14 Geminid meteor shower, usually the year’s best, averaging about 50 meteors per hour. But the light of a waxing gibbous Moon may hamper viewing until moonset around 3 a.m. December 19 Full Moon rises at sunset against the feet of Gemini the Twins. Look nearby for Saturn, which is at its brightest in nearly three decades. Known as the “Cold Moon” to the Algonquin and the “Turning Moon” to the Zuni. December 21 Winter solstice at 5:13 p.m. in the Northern Hemisphere. This marks the beginning of Winter and the shortest daylight period of the year. In locations north of the Arctic Circle, the Sun does not rise all day. South of the equator, where the seasons are reversed, this is the start of Summer. Within the Antarctic Circle, the Sun does not set all day.
Times are for San Francisco, CA, and are accurate to within two minutes. B.F. Quock, Morrison Planetarium, bquock@calacademy.org The PlanetsMercury Only two good chances remain this year to glimpse this elusive little planet. One is before dawn very early in the month. It may be easiest to see on the morning of October 6, when it’s very low in the east, just below brighter, orangish Mars. The other, more convenient opportunity will be at the end of December, when Mercury may be seen very low in the west just after sunset. Venus At the beginning of October, the gleaming planet named after the Roman goddess of beauty is very low in the west at sunset, and difficult to see in the glow of twilight. Hidden from view by the rising Sun’s rays, it reappears in the morning sky around mid-November, gradually climbing toward an early-December meeting with Mars. The Moon swings past on the evenings of October 7 and 8, and comes close by on the morning of December 1. Mars The “red planet” is a morning object this season, rising in the east before the Sun as it slowly passes through the stars of Virgo. Look nearby on the morning of October 10 for Mercury; from late-November through the end of the year, Venus joins Mars in the predawn sky. The waning crescent Moon passes nearby on the mornings of October 4 and 5, November 2, and December 1. Jupiter In October, the giant of the planets rises well before dawn and is high in the south by sunrise, located against the faint stars of Cancer. By December, it will be descending in the west at sunrise, slowly crossing from the stars of Cancer into those of Leo. Saturn The “ringed planet” rises in the east just before midnight in October, located against the stars of Taurus, and gradually rises a few minutes earlier from night to night. On December 17, Saturn reaches opposition, which makes it visible all night long. An extra-special challenge for experienced amateur astronomers: look in the same telescopic field on December 19 for Saturn and the Crab Nebula, the remnant of an exploded star. Will the bright light of the nearby Full Moon obscure the Crab from view? The Moon passes Saturn on October 25, November 21, and December 18. Lord of the Rings The majestic, ringed planet Saturn makes one of its best appearances in decades, reaching opposition in December, when it and the Sun are on opposite sides of the sky as seen from Earth. The planet is simultaneously nearing perihelion, or its closest approach to the Sun. This occurs in February 2003 and happens only once during Saturn’s 30-year orbit. In addition, the tilt of the planet’s north pole away from Earth gives us a view of the southern face of the famous rings, maximizing the amount of sunlight that Saturn reflects back to our eyes. All three of these factors combine to make Saturn brighter than it has been since its last perihelion in 1974. Through telescopes, amateur astronomers should easily be able to make out the magnificent rings and perhaps even the prominent Cassini Division within them. |