Scobee Planetarium at San Antonio College

Celestial Sights for San Antonio Nights – January, 2009

January Sun – While it may be difficult to tell, believe it or not, the days are getting longer! With the passage of the Winter Solstice and the shortest day of the year on December 21st, the amount of time the Sun spends in the San Antonio sky is increasing ever so slightly.

The first day of January finds the Sun rising above the southeastern horizon at 7:28am and setting in the southwest at 5:46pm. This represents a total of 10 hours and 18 minutes of possible sunshine. By month’s end, the Sun rises at 7:24am, sets at 6:10pm, and is visible for 10 hours and 46 minutes – a net gain of 28 minutes of daylight.

Not only is the amount of sunlight increasing, the same is true for the Sun’s altitude. On January 1st our star reaches a maximum elevation of 37 degrees at “solar noon” – the Sun’s highest point above the southern horizon during its travel across the daytime sky. By January 31st this angle grows to 43 degrees above the southern horizon at solar noon. Remember, this number represents angle of measurement, not degrees of temperature. This trend of increasing sunshine eventually brings the longer and warmer days of Spring.

Also of interest, the Earth reaches perihelion, its nearest point to the Sun on January 3rd. On this day the Earth is approximately 91,346,000 miles from our star. Near the end of month, the New Moon passes between the Earth and Sun on January 26th producing a solar eclipse. This event will be best viewed from Indonesia and across the Indian Ocean. Unfortunately, no portion of this solar eclipse will be seen from our half of the planet Earth.

January Moon - Our lunar companion starts the New Year sharing the evening skies with the brightest of all the planets, Venus. In fact, the Moon visits Venus twice this month. On January 1st, a thick lunar crescent hovers above the brilliant sparkle of Venus. A similar scene takes place near the end of January. Starting the month already in crescent phase, with each passing evening the Moon glides eastwards through the constellations, growing both in phase and illumination. First Quarter Moon takes place on January 4th with the Moon well placed for observation among the stars of Pisces. Growing brighter, a waxing gibbous Moon glows alongside the sparkle of the Pleiades star cluster in the constellation of Taurus on the night of January 7th. Three nights later, a brilliant full Moon highlights the winter night of January 10th. On that evening, the full Moon is situated among the stars of Gemini, the Twins. While January’s full Moon is known by several names, this month’s Full phase is sometimes called “the Moon after Yule” or “the Old Moon.” One other accolade belongs to January’s full Moon – it is the “closest” full Moon of 2009!

Having reached full phase, the Moon rises later and later with each passing evening. During the late night hours of January 14th the Moon and the planet Saturn share the sky among the stars of Leo the Lion. Three nights later, the Last Quarter Moon rises with Spica, brightest star of Virgo. Prior to sunrise on January 21st, a thin lunar crescent hovers alongside Antares, the “heart star” of the Scorpion. New phase takes place on the January 26th with the New Moon eclipsing the Sun. This solar eclipse takes place primarily over the Indian Ocean. Sorry, no glimpse of January 26th’s solar eclipse will be visible from our side of the planet.

Returning once more to the evening sky, keen-eyed observers may spot a razor-thin lunar crescent just above the sunset horizon on January 27th, or you might have to wait until the 28th to catch this sight. The Moon shines below Venus on the 29th. The next night, the Moon appears above Venus on January 30th.

January Moon Phases

First Quarter Moon – January 4th Full Moon – January 10th

Last Quarter Moon – January 17th New Moon – January 26th

January’s Evening Planets

Mercury, the Sun’s closest world, begins the New Year in the evening sky alongside the planet Jupiter. Early in the month, both Mercury and Jupiter appear briefly together in the evening twilight, Mercury being the slightly higher and dimmer of this planetary pairing. As the month progresses Jupiter drops deeper into the solar glow and departs the celestial scene, with Mercury visible until January 10th. Thereafter, Mercury begins its own rapid descent into the solar glow. Mercury is in solar conjunction on January 20th and thereafter this elusive planet shifts into the morning sky. During the last week of the month, Mercury passes by Mars. However, this planetary pairing takes place very near the sunrise horizon and may prove too difficult to observe against the glare of morning twilight.

Jupiter, the giant planet, begins the New Year in preparation to depart the celestial stage. As noted earlier, during the first week of January, both Mercury and Jupiter appear briefly together above the southwestern evening skyline. Slightly brighter Jupiter appears just below dimmer Mercury. However, before reaching the middle of the month, Jupiter descends into the Sun’s all-consuming glow and is lost from view. The giant planet is in solar conjunction on January 23rd. After this date, the planet moves into the morning sky, but it will be few weeks before Jupiter is visible prior to sunrise.

Venus – The brightest of all planets puts on a dazzling display following a January sunset! Sparkling like a brilliant diamond in the frosty sky, reaches the peak of its evening celestial show. On January 14th, Venus reaches its greatest angular separation from the Sun. Simply put, now is the best time to enjoy Venus at its highest point in our evening sky! As mentioned earlier, Venus and the crescent Moon are near one another on January 1st and again at month’s end. On January 29th, a thin lunar crescent shines below Venus. The next night of January 30th finds the Moon just above Venus. Venus sets about 4 hours after the Sun and is a glorious sight following a January sunset. Be careful, though. Outshining all in the sky except for the Moon, Venus is often mistakenly labeled a “UFO.”

January’s Late Night Planets

Saturn, the planet with the brightest rings, begins the New Year amidst the stars of Leo the Lion. On January 1st, Saturn clears the eastern horizon just after at 11:00pm. Look for the planet’s yellow-white glow near Denebola, the so-called “tail star” of Leo. As mentioned earlier, Saturn and the Moon share the late night skies of January 14th. This pairing of Moon and planet can be seen in the east by 11:00pm and throughout the predawn hours. By the end of January, Saturn rises almost two hours earlier, ascending above the eastern horizon by 9:00pm. A small telescope reveals the planet’s spectacular rings have almost disappeared. Twice during Saturn’s 29-year orbit around the sun, the planet’s rings are presented to us “edge-on.” When this happens, they become hard to observe because they’re so thin. The rings are “closing up” right now and are presented at less than a one-degree angle to us. They will appear completely edge-on this coming September.

January’s Morning Planets

Mars – Although technically a morning object, Mars remains too near the solar glow for any chance of observation. A brief encounter with the planet Mercury during the last week of January 24th occurs just above the predawn skyline. However, this pairing may prove too difficult to observe against the bright morning twilight. Best wait another month for Mars to move farther from the solar glow.

Wishing you clear skies!

Bob Kelley

Scobee Planetarium Educational Specialist

210-733-2910 or bkelley@mail.accd.edu