| The Magazine of the CALIFORNIA ACADEMY OF SCIENCES |
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Skyguide Mars Revisited October 2: First Quarter Moon. You might see something that resembles a rabbit bounding out of the Moon’s shadows. The “rabbit” is formed by dried lava flows, or maria. October 10: Full Moon at 12:27 a.m., but it appears full about a day before until about a day later. The first full moon after September’s Harvest Moon, it is often called the “Hunter’s Moon.” October 21: The peak of the Orionid meteor shower just before midnight. The shower stems from the dust of Haley’s Comet and averages about 15 meteors per hour. October 25: New Moon at 5:50 a.m. Very soon after sunset, the crescent Moon is only 131/2 hours old––a challenge for observers with binoculars. Look very low in the west-southwest. October 26: End of Daylight Saving Time at 2:00 a.m.––for convenience, adjust clocks back the night before and gain an hour of sleep. The U.S. was on Daylight Saving Time year-round from February 2, 1942 to September 30, 1945. November 8: Full Moon, also known as the “Frosty Moon” and the “Beaver Moon.” A brief total lunar eclipse occurs with the Moon passing through Earth’s reddish shadow. November 17: Peak of the Leonid meteor shower averages about 15 meteors per hour, but moonlight may obscure the show. November 22: Peak of the minor Alpha Monocerotid meteor shower, with no interference from moonlight. It rides on the coattails of the more famous Leonids. This display gives brief but intense outbursts every decade or so; the last was in 1995, so it might show an increase over its usual trickle of about 5 meteors per hour. The shower seems to radiate from the constellation Monoceros the Unicorn, which rises around 10 p.m. just behind Orion. November 23: The New Moon occurs at 2:59 p.m. pst, too late for a crescent to be visible at sunset; look tomorrow. Observers in parts of Antarctica will see the New Moon move directly between the Earth and the Sun in a total solar eclipse. Partial eclipses will be visible from the rest of Antarctica, New Zealand, most of Australia, southern Argentina and Chile. December 8: Full Moon, also known as the “Moon before Yule.” This Full Moon—the closest to the Winter Solstice—arcs high overhead and lingers above the horizon, while the Sun makes a low, short arc across the sky during the day. December 13: Peak of the annual Geminid meteor shower. Typically the year’s strongest display, it averages about 50 meteors per hour, though moonlight once again interferes. It’s caused by the dust of asteroid Phaethon, thought to be a depleted comet. December 21: Solstice at 11:04 p.m. pst marks the start of Winter in the Northern Hemisphere. The Sun crosses the sky lower today than on any other day of the year. December 22: Peak of the Ursid meteor shower, a lightweight display which usually produces about 10-15 meteors per hour. It radiates from Ursa Major, which is low on the northern horizon at sunset and high in the northeast by midnight. December 23: New Moon at 1:43 a.m. pst. Just after sunset, binoculars may be needed to see the thin but gorgeous 15-hour-old crescent Moon low in the southwest. Planets Mercury: Rising before dawn at the beginning of October, the speediest planet soon disappears into the Sun’s glow by mid-month. Passing superior conjunction on October 25, Mercury emerges in the evening sky in December low in the southwest after sunset. It pursues Venus but never quite catches up. Venus: Keeping pace with the Sun's eastward motion against the stars, the brightest planet is an evening object for the rest of the year. It zips from Libra through Scorpius, Sagittarius, and into Capricornus by the New Year. The young crescent Moon pairs with Venus on the evenings of October 26, November 25, and (quite strikingly) December 25. Mars: Brightness waning after its late-August opposition, the Red Planet still dominates the eastern sky after sunset, rising in October against the stars of faint Aquarius. Through November and December, it slowly moves into Pisces. It rises slightly earlier each night, and is nearly due south at sunset by year's end. The nearly-full Moon swings by on October 5 and 6, November 2, and December 1. Jupiter: Now a morning object, Jupiter rises in the east before dawn against the stars of Leo, competing with the bright star Regulus. It rises a few minutes earlier from one morning to the next, inching gradually farther from the Sun each dawn—by the end of the year, it will have crossed into the western half of the sky by sunrise. With more than 60 moons of its own, Jupiter is passed in the sky by Earth's single satellite on the mornings of October 21, very close on November 18, and December 15 and 16. Saturn: Rising about midnight in October and located due south at dawn, the Ringed Planet slowly descends into the west from morning to morning. Slowest-moving of the planets visible to the naked eye, Saturn remains ensconced against Gemini all season. It passes opposition on December 31, when it rises at sunset and is visible all night. The Moon appears nearby on October 17, November 13, and December 10 and 11.
Times are for San Francisco, CA, and will vary slighly for other locations. This Time, We Invade Mars A fleet of four spacecraft is headed for Mars, signaling another round in the planet’s high-stakes exploration. If things go well, the European Space Agency’s Mars Express will deliver the Beagle II lander in December to search for life in the rusty soil. The Japanese Space Agency’s Nozomi spacecraft, formerly known as Planet-B, will end an odyssey that began in 1998. After a miscalculated trajectory, a corrective thruster burn that used up fuel, and radiation damage from a solar flare, it should arrive in December —four years late. It will spend two years in orbit studying the Martian atmosphere and looking for a ring of dust around the planet. NASA’s twin Mars Exploration Rovers Spirit and Opportunity should arrive in January, one setting down in Gusev Crater and the other in Meridiani Planum. Both rovers will examine rocks and search for evidence of water, which may once have flowed in abundance at the two landing sites. Bing F. Quock is a member of the Morrison Planetarium staff at the California Academy of Sciences. bquock@calacademy.org |