On a moonless night, view the gegenschein

According to Guy Ottewell in his Astronomical Calendar 2007, late February on clear moonless nights is the best time to look for the zodiacal light and gegenschein. Zodiacal light is a diffuse band of light visible along the eastern horizon before sunrise or the western horizon after sunset. It is caused by sunlight reflecting and scattering off grains of interplanetary dust in the plane of Earth’s orbit. Gegenschein, German for “counterglow,” also is caused by the reflection of sunlight off interplanetary dust and appears around midnight as a glowing spot on the ecliptic opposite the sun. Some astronomers believe gegenschein may be caused by the reflection of sunlight off large particles as far away as the asteroid belt between Mars and Jupiter.

Focus on the planets

Saturn is the dominant feature in the evening sky during February while Jupiter plays a similar role in the early morning hours.

Mercury is low on the western horizon shortly after sunset early in the month. Look for Mercury just to the lower right of much brighter Venus where it remains until midmonth when it disappears into the sun’s glare. The best evening to spot Mercury will be Feb. 7, after which it sinks rapidly toward the horizon.

Venus shines brightly in the west as darkness falls. Venus will continue to climb higher in the sky as the winter draws on.

Mars is very low in the east-southeast at dawn among the stars of Sagittarius. Mars is now very faint but will steadily brighten and grow larger throughout 2007.

Saturn rises in the east at nightfall and remains in view until nearly dawn. Saturn will be closest to Earth and at its brightest for the year during February with the best viewing occurring around midnight. The tilt of Saturn’s ring system has been closing over the past few years and will be a disappointing edge-on by 2009. Enough remains for a good telescope to pick up the rings and gaps in Saturn’s fabled system.

Jupiter rises in the southeast two to three hours after midnight during the month and is well up on the horizon just before dawn. The star just slightly to Jupiter’s lower right is Antares.

Uranus may be spotted around 7 p.m. Feb. 6 or 7 when the distant planet lies just to the north of Venus.

Neptune is lost to view during the month.

February events

7 The moon is at apogee or farthest distance from Earth today. Look for Mercury to the lower right of sparkling Venus low in the southwest an hour after sunset.

10 Moon in last quarter, 4:51 a.m. Saturn is conspicuous on the eastern horizon about 8 tonight. Its rings and major moons are readily visible by telescope.

11 The moon shines high in the southeast before dawn with Jupiter well to its left and reddish-orange Antares sandwiched between them.

14 Happy Valentine’s Day! Celebrate by finding the moon nestled among the stars of Sagittarius on the southeastern horizon with faint reddish Mars barely visible just to its left.

16 The sun enters Aquarius on the ecliptic.

17 New moon, 11:14 a.m.

19 The sun enters the astrological sign of Pisces but astronomically has just entered Aquarius. The moon is at perigee or closest approach to Earth today.

20 Look for brilliant Venus in the southwest about an hour after sunset with the waxing crescent moon high overhead. Mercury might be spotted very low on the horizon far to the lower right of Venus. Today is Mardi Gras or “fat Tuesday,” the start of Lent.

23 The Pleiades can be spotted next to the moon tonight.

24 Moon in first quarter, 2:56 a.m.

28 Working upward, Regulus, Saturn, the moon, and Pollux of Castor and Pollux form nearly a straight line on the eastern horizon about an hour and a half after sunset. Sunrise, 6:15 a.m.; sunset, 5:22 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 04402.