January 2014 Night Skies over
Tanzania and the Year Ahead
Lunar phases occur according the positions of the Moon in its orbit around the earth. For example the New Moon occurs when the longitude of the Moon is aligned with that of the Sun. Full Moon occurs when they are exactly opposite each other.
Positions of the Moon in its orbit are known precisely and can be predicted extremely accurately. Astronomical phenomena associated with the Moon, such as its phases (New Moon, Full Moon, First Quarter, Last Quarter), and other phenomena such as solar and lunar eclipses can be predicted thousands of years in advance to within of fractions of a second.
This year’s 2014 New Moons for example are calculated to occur on the following Tanzanian times: January 1, Wed. 14:15(2:15PM), January 31, Fri. 00:40(12:40AM), March 1, Sat. 11:02(11:02AM), March 30, Sun. 21:48(9:48PM), April 29, Tue. 09:17(9:17AM), May 28, Wed. 21:43(9:43PM), June 27, Fri. 11:10(11:10AM), July 27, Sun. 01:42(1:42AM), August 25, Mon. 17:13(5:13PM), September 24, Wed. 09:13(9:13AM), October 24, Fri. 00:56(12:56AM), November 22, Sat. 15:32(3:32PM), and December 22, Mon. 04:36(4:36AM).
The Moon shifts by approximately 12 degrees in the sky every day (360 degrees/30 days) and in that time is grows in size and brightness. Hence one day after the New Moon, the Moon will be AT LEAST 12 degrees above the western horizon at sunset. By this time, the Moon will be big enough, high enough and bright enough to be observed from flat horizons in clear skies unobstructed by clouds or haze. Hence the First Crescent, which is the first moonsighting of the lunar month, can be reasonably foreseen within a day of the New Moon. Hence many public holidays that follow the sighting of the First Crescent, especially those that follow several days after the sighting of the First Crescent can be reasonably foreseen and prepared for.
The January 1 New Moon ushered in the lunar month in which Maulid is celebrated on the 12th night from the First Crescent sighting. The New Moon on January 1 occurred at about 2 pm, hence the Moon had only about 4 hours until sunset to shift up the horizon by about 2 degrees. This is not sufficient to observe the first crescent since it is extremely slim and hidden in the horizon glare on January 1. However, by the next day, January 2, it had more than 28 hours to move in its orbit to shift away from the Sun in the sky, and would be at least 14 degrees elevation above the horizon at sunset. Hence it would be very possible to be observed in good skies. The twelfth night from the First Crescent of January 2 would make it January 13 as the night of the celebrations. So the public holiday would be on January 14, which was indeed the case. An announcement immediately after January 2 would provide at least 10 or 11 days of notice of the holiday. Unfortunately it was only announced just a few days before the holiday. We can use our knowledge of astronomy, to organise the crescent observations and from which good notice can be given to enable the public to plan their work to account for such holidays. New Moons to follow this year are those on June 27, Fri. 11:10(11:10AM), July 27, Sun. 01:42(1:42AM), and September 24, Wed. 09:13(9:13AM).
In terms of eclipses, this new year 2014 will be a quiet year for Tanzania. Though there will be four eclipses around the world, none of them will be visible in Tanzania and most parts of Africa. Two Solar eclipses will occur - one on April 29 in the south polar area and Australia, while the one on October 23 will occurs over the north polar area and North America. The two deep Lunar eclipses will occur on April 15 and on October 8, both centered over the Pacific Ocean. Obsevers in the America’s will enjoy these. Solar eclipses occur when the Moon is New, while Lunar eclipses occur when the Moon is Full.
You will notice from the dates (April 15/April 29 and October 8/October 13), that both the Solar eclipses this year occur at the next New Moon after the Full Moon on which the Lunar eclipses occurred. This is because during the 14 day interval between the Full Moon and the New Moon, the Moon is still within the same plane and hence in a straight line with the Earth and the Sun to allow exact interception of sunlight before it reaches either the Moon or the Earth.
Among the planets, Jupiter is the brightest planet in the east, and has replaced brilliant Venus which was our constant companion in the west for several months at the end of last year. Having just reached opposition on January 5, giant Jupiter rises soon after sunset at the moment, and can be seen throughout the night since it is overhead at midnight and drops below the western horizon just as the rises in the west. As the days go by, Jupiter will rise earlier so that it will be higher in the sky at sunset with each passing day. It will be with us visible as a bright star for the next six months and will disappear in the western sunset skies by the end of June.
Venus has moved from the western evening sky and now shines as a brilliant morning star in the east. Through a telescope it is currently a large thin crescent and will continue to rise and become half shape when it is highest elevation of about 45 degrees in the sky at end of March, and will then get lower day by day and disappear from the morning sky by the end of July.
Mars will also be interesting to follow in the coming months as it approaches Earth in its orbit. It can be seen in early evening skies from March 2014 to March 2015. It will enter the evening skies from the end of February when it rises around 10 pm. It reaches maximum brightness when it reaches opposition to sun on April 8 when we will see it shine bright red with the Sun directly behind us as it sets in the west while the red planet rises in the east.
The ringed planet Saturn, the most beautiful jewel in the sky (when viewed through a telescope), currently occupies the morning sky. It enters the evening skies from the beginning of March rising in the east around 10 pm. By beginning April it will be rising by 8 pm. It will reach opposition and brightest on May 11 and will be visible in the evening skies until beginning November.
While planets shift slowly eastwards across the stationary background stars, Mar will show its retrograde (opposite) motion from the beginning of March. It will be close to the bright star Spica in Virgo constellation which can be used a reference background star to witness the backward motion of Mars. The close spacing of Mars and Spica in the sky will provide attractive configurations when the Moon comes close to or between the pair on Jan 23, Feb 20, Mar 19, Apr 15, May 12, Jun 9, July5/6, Aug 2/3 with Saturn, Aug 31 with Saturn only, and Sep 28/29 with Saturn and Antares.
Lastly Mercury the elusive planet will rise highest in the evening sky to around 20 degrees on Jan 29, May 24 and Sep 19 when this tiny planet will be far off from the glare of the horizon sunset brightness to be seen with naked eyes.
This is a month when the our southern skies come alive with dense collections of stars, nebulae and galaxies since the densest potions of our Milky Way enters our skies. The Orion constellation, seen from our skies as a big rectangle crossed with three diagonal stars, is the most recognizable constellation for the next five months as it shifts from east to west. From March, the Southern cross is easily identified also. The brightest stars brightest stars in the whole sky, Sirius and Canopus are accompanied by Capella, Rigel, Procyon, Achernar, Beltelgeuse, Aldebaran. These are among the top ten brightest stars in the sky, so go out and know your stars.
The Milky Way contains a dense collection of stars and interstellar dust and nebulae stretching across the sky from the southeast across the sky to the north, grazing Sirius, Orion, Taurus and finally enclosing Perseus and Cassiopeia in the north. Three visible galaxies can be seen in the early night sky for the next few months. Two of these, the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC) are members of our local group with our Milky Way galaxy. Only southern observes can see the two Magellanic Cloud galaxies since they are close to the South Pole. They both have irregular shapes and cover a wide area of the sky with more than 4 to 5 degrees of angular width. LMC lies between Canopus and the South Pole and can best be viewed after 9 p.m. The SMC (3½ deg across) lies similarly between Achernar and the South. These two galaxies are about 50,000 light years away from us. The Andromeda galaxy can be seen in the north above Cassiopeia. It is more than 2 million light years away from us and can be seen as a fuzzy patch of light, making it the farthest object seen with the naked eyes.