Mystery of seasons unravels

I am adopting a slightly different format for Maine Skies starting this month. After 20 years of including a constellation with each column, there is little left to be said about them. Also, there are many books readily available that can tell you more about them than I can in the space available. So the constellations will be replaced with Our Celestial Neighborhood, devoted to answering oft-asked questions or descriptions of some of the oddball objects in the universe. You can send questions or comments to me at cgmewood@aol.com or care of the Bangor Daily News, Style Desk, P.O. Box 1329, Bangor 04402.

Focus on the Planets

Mercury makes a brief appearance during the last three days of January. Look for it low in the southwest at dusk near the horizon to the lower right of Venus.

Venus puts on a dazzling display high in the southwest at nightfall, remaining in view for much of the night. On the night of Jan. 16, Venus will appear precisely half-lit and half-dark by telescope.

Mars is well up on the southern horizon at dawn. The Red Planet still is disappointingly dim but brightens steadily throughout 2001.

Jupiter is high in the southeast at sunset. Aldebaran, the “red eye of the bull,” lies just below, and slightly to the left of Jupiter. Near the horizon, in line with Jupiter and Aldebaran, is giant Betelgeuse.

Saturn is found to the upper right of Jupiter. Note the Pleiades star cluster to Saturn’s immediate left.

Uranus and Neptune still wander among the stars of Capricornus but are so dim that they will prove a challenge even to those with a good telescope and finder’s chart.

Pluto is a lost cause to everyone in January.

Our Celestial Neighborhood

This year, the Earth is closest to the sun Jan. 4 and farthest away July 4. Since it is always the case that the sun is more distant in the summer months, why is it colder in the winter?

The distance to the sun actually plays a minor role as the difference in the two extremes figures out to be only about 3.4 percent. The fact that the Earth tilts on its axis by 231/2 degrees is why we have the seasons. At the June 21 summer solstice, the Northern Hemisphere is at maximum tilt toward the sun and we receive the full benefit of its rays. At the winter solstice on Dec. 21, the tilt favors the Southern Hemisphere and we are in winter’s grip.

The tropics are defined by the Tropic of Cancer at 231/2 degrees north latitude, when the sun appears at its zenith at noon on the first day of summer, and the Tropic of Capricorn at 231/2 degrees south latitude when the same is true for the Southern Hemisphere. Inhabitants between these two points marked out from the equator have roughly the same amount of solar radiation all year long.

January Events

1 Sunrise, 7:13 a.m.; sunset, 4:05 p.m.

3 Peak night for the Quadrantid meteor shower. Look for a display of about 60 meteors per hour out of the northeast after midnight. The Quadrantids are bright, medium velocity meteors, with a few leaving persistent trails.

4 The Earth is at perihelion, or nearest approach to the sun.

5 Saturn, Jupiter, the moon, and Aldebaran form an arc on the southeastern horizon tonight.

9 Full moon, 3:25 p.m. The full moon of January is called the Old Moon or Moon After Yule. The moon will be ending a total eclipse as it rises for New Englanders.

10 The moon is at perigee, or closest approach to the Earth, today. This event, coupled with the closeness of the full moon, could give rise to abnormally high tides.

16 Moon in last quarter, 7:36 a.m.

19 The sun enters Capricornus on the ecliptic.

20 The sun enters the astrological sign of Aquarius even though, in physical reality, it has just entered Capricornus.

24 New moon, 8:08 a.m. The new moon is at apogee – or the farthest from the Earth – for the month.

28 Look for the crescent moon to the lower right of Venus on the southwestern horizon. Far to the lower right is Mercury.

31 Sunrise, 6:56 a.m.; sunset, 4:42 p.m.

Send astronomical queries to Clair Wood at cgmewood@aol.com or care of the Bangor Daily News, Style Desk, P.O. Box 1329, Bangor, Me. 04402.