Here’s a common question: How many stars can you see with the naked eye on a clear night?
Every eye is a bit different but under ideal conditions the most frequent number given is 2,000 to 2,500, all of which belong to our Milky Way galaxy. With powerful binoculars this can increase to about a half million, still all in the Milky Way. We can also see fuzzy points of light that are galaxies but not the individual stars. The Andromeda galaxy contains about 500 billion stars!
Here’s the usual follow-up question: How many stars are there in total? This question cannot be answered. The observable universe is estimated to have over 100 billion galaxies each with around 300 billion stars. There are likely countless more galaxies at such a distance their light has not had time to reach us.
Perhaps the title of the last book written by renowned astronomer Carl Sagan just before his death in 1996 says it best. He simply called it “Billions and Billions.”
Focus on the planets
Mercury and Venus are paired together in the west-southwest as the night darkness deepens with Mars well to their upper left. Jupiter reigns from midnight to dawn.
Mercury is low in the west-southwest about a half hour after sunset. Mercury is easily spotted as it is in close proximity to brilliant Venus until mid-month.
Venus is blazes in the southwest at dusk and cannot be mistaken for anything else in the night sky.
Mars is high in the southwest, to the far upper left of Venus, as darkness falls. The far distant planet is so dim that no details can be seen, even by telescope.
Jupiter rises in the southeast around 8:00 p.m. as the month opens and about sunset as it ends. Details such as the belts are obvious and the Great Red Spot may be seen if facing Earth. The four Jovian moons will be easily seen, and it is reported that a rare treat for telescope viewers will occur on the night of Jan. 23 when the shadows of three moons can be seen as they cross the planet’s surface.
Saturn rises in the southeast about 4:00 a.m. as January opens and around 2:00 a.m. as it closes. The rings are still tilted to show detail and there is a close pairing of Saturn and the crescent moon on Jan. 16.
Uranus is high in the south-southwest as dusk deepens where its blue-green disk may be spotted by telescope.
Neptune is just to the upper right of Mars after dark. Use Mars to find the elusive blue-gray planet on Jan. 19. Both of the outermost planets can be more easily found using the finder charts published by Sky & Telescope magazine at skypub.com/urnep.
January events
1: Sunrise, 7:13 a.m.; sunset, 4:05 p.m.
3: Look to the southwest a half hour after sunset where Venus shines brilliantly with Mercury to its immediate lower right. Mars is located far to the pair’s upper left.
4: Full moon, 11:53 p.m. The full moon of January is known as the Wolf Moon and the Moon After Yule. The Earth is at perihelion or closest approach to the sun for the year. This is the peak night for the Quadrantid meteor shower that normally produces rates of up to 120 meteors per hour. Since it is falling at the same time as the full moon, viewers will be lucky to spot 10 – 12 of the brightest per hour.
9: The moon is at apogee or furthest distance from the Earth.
10: There is an extremely close pairing of Venus and Mercury in the west-southwest about an hour after sunset.
13: Moon at last quarter, 4:46 a.m.
16: Saturn is joined by the thin crescent moon in the southwest an hour before sunrise.
20: New moon, 8:14 a.m. The sun enters Capricornus on the ecliptic while, a few hours later, enters the astrological sign of Aquarius.
21: The moon is at perigee or closest approach to the Earth.
26: The moon is at first quarter, 11:48 p.m.
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, Features Desk, P.O. Box 1329, Bangor, ME 04402.