january2009nightskiesovertanzania
January 2009 Night Skies over Tanzania
NIGHT SKIES OVER TANZANIA
JANUARY 2009
By Dr N T Jiwaji
ntjiwaji at yahoo dot com
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NIGHT SKIES OF JANUARY AND ASTRONOMICAL EVENTS OF 2009
By Dr. N T Jiwaji
ntjiwaji@yahoo.com
This first month of 2009 has ushered in the International Year of Astronomy (IYA2009) which has been declared by the United Nations to be marked all over the world under the technical guidance of the International Astronomical Union (IAU) and coordinated by UNESCO. It was officially launched this month on 15th January at the UNESCO Headquarters in Paris, France with nearly 900 representatives from almost all nations.
IYA2009 is celebrated to mark the 400th year since Galileo first looked at the skies and saw amazing features on the Moon and the visible planets. This curiosity has not been diminished, and anything has increased and spread to billions of people who share the same skies and wonder what lies out there in deep space. Astronomy has spurred our understanding of fundamental science that applies for the vast scales that span our Universe as well as the tiniest scale of the sub-particles within the nucleons in the nucleus of atoms that we are made of.
This whole year, and beyond, will be marked through various activities and projects which include the opportunity for everyone to get a chance to look at the skies just as Galileo did, using a simple telescope; stargazing sessions held for the public with some coordinated sessions of simultaneous sessions with other parts of the world during 2-5 April, training of teachers in Astronomy, access to daily diaries of activities of astronomers from all over the world, exhibitions, movies and many more…
Among the astronomical events that normally catch the public’s attention, eclipses are the most popular. Although 2009 has unusually high number of eclipses (six), only the last one on the last day, in the last hours of the year will show some effects for us.
An annular solar eclipse that will take place on 26th January will be just skipped by Tanzanians unless you are living close to the border with Mozambique along the shores of the Ruvuma River, and even then you will see only the extreme edge of the sun being covered up by the Moon between 9:30 and 10:00 am. The whole eclipse will last between 7:56 am and 2:00 pm our time.
The next two eclipses are lunar eclipses that will also be a disappointment since only the penumbra (very faint shadow) will cover the moon. First such event will be on 9th February between 3:36 pm and 7:40 pm hence for us when the moon is rising above the eastern horizon. The second such event of 7th July will occur during our daytime between 11:32 am and 1:45 pm.
The world will witness a total solar eclipse on 22nd July 2009, but only in the eastern hemisphere from India to China and the Pacific so we will not be able to witness that eclipse also. The best place to observe the eclipse will be in China and it will occur between 3:51 am and 7:20 am our time.
The next eclipse is again a penumbral (faint shadow) lunar eclipse on 6th August 2009 so though it is centred on Africa we will not be able to see any change in the Moon. The eclipse will occur between 3:01 am and 5:18 am our time.
The last eclipse of the year will just save the year from complete disappointment since we will see a partial lunar eclipse during which the earth’s shadow will cover a small part of the moon at its southern edge on 31 December. It will close the year and will end half an hour into the New Year 2010. The dark shadow (umbra) will be seen between 9:51 pm and 10:54 pm while the whole eclipse will last from 8:15 pm to 00:30 am just after midnight.
During this year, the planets will appearing and disappearing from our view as they move about in their orbits and their positions relative to earth change. Mercury the planet closest to earth and fastest moving will shift its position around the sun alternating between the evening and morning skies for times during the year, rising to high and visible altitudes of upto 26 degrees above the horizon at sunset or sunrise.
Venus has been high in the evening sky has been visible as a very bright star in the western skies in the evenings for more than two months. By January 14th it had risen to its highest altitude of 47 degrees above the horizon but is still just as high since it shifts very slowly at this time. It is in a half phase condition and through a telescope looks as if you are looking at a half moon. It is now changing to crescent phase and is a very interesting object to observe as its shape changes from a thick to a thin and distinct crescent while its apparent size increases day by day as viewed through a telescope. It remains very bright throughout since the thinning of the crescent is compensated by increase in its apparent diameter. Hence it is the most interesting object to observe in the evening skies from the end of the month.
In fact on 30th January the crescent Moon will be close to Venus (also in crescent phase) and will form a remarkable pair in the sky as seen in the simulation pictures.
After mid March it will be too close to the sun to be seen and will then appear as a morning star which can be visible from mid April onwards in the eastern skies at dawn. Here it will reach its maximum altitude on June 5 and will again be lost in the glare of the sun by Jan 11 2010 after which it will swing back into the evening skies.
Mars is a tiny red dot visible only after midnight and is best seen in the early morning before sunrise at dawn. It is approaching earth during the year and it will become brighter as its apparent diameter increases. It will come closest to earth at the end of January of 2010 next year.
Jupiter, at the moment is getting closer to the sun in the western sky coming closest on 24th January so being invisible. It will then enter the morning skies where it will stay until it enters the evening skies from mid July rising around 9 pm. It will rise at sunset (at opposition with the setting sun and hence brightest) from August 14th. Its four Galilean moon (first observed by Galileo 400 years ago) move quickly in their orbits and so their positions change significantly even in a matter of a couple of hours when viewed through a telescope.
Saturn is also currently in the morning skies but will become visible in the evening skies rising around 9 pm from the beginning of February and by 8th March it will be at opposition and rising in the eastern sky at sunset and will be best visible. The rings of Saturn will not be as prominently seen this year since they are being viewed edge on hence we will not see the distinct ring shape but just a line that cuts across the disk of the planet. This situation occurs only once in about 15 years and most likely Galileo also saw Saturn in this condition when he first looked at the Saturn through a telescope 400 years ago. Hence he was not able to identify the ring system and drew the shape as though Saturn had ears!
Among the stars, Sirius and Canopus on are the brightest stars in the whole sky. They can be called the jewels of the south for being the brightest as well as the most regularly visible stars in our skies. Other bright stars which fall in the top 20 brightest in the whole sky are, Procyon, and in the prominent and very recognizable Orion constellation with a rectangular are Rigel and Beltelgeuse. In the Taurus constellation with a marked V shape representing the head of a bull, is Aldebaran. Beltelgeuse and Aldebaran are stars that are in the final stages of their lives with a size so big that they would engulf most of our solar system. They are called Red Giants because their surfaces are much cooler (1000 degrees) than normal stars (about 5000 degrees) and thus emit red light rather than white light; or even blue light for hotter stars. Other bright stars are Capella and Achernar. Canopus has a special property that it is a star well removed in the sky from other bright stars so it is easy to locate and forms a common beacon when looking for an icon to follow in lonely skies. The Milky Way containing a dense collection of stars and interstellar dust and nebulae is marked as a grey band and stretches across the sky from southeast across the sky to the north, grazing Sirius, Orion, Taurus and finally enclosing Perseus and Cassiopeia in the north.
Over the next couple of months we will be able to observe three visible galaxies. The Large and Small Magellanic Clouds (SMC & LMC) are the closest galaxies to us after our own Milky Way Galaxy, only 50,000 light years away. Of course this is not really close, because you can remember that the star closest to us and within our own galaxy Alpha Centauri, is only 4.3 light years away from us. The two Magellanic Cloud galaxies can be seen only in the southern skies since they are so close to the south point. The both have irregular shape and cover a wide area of the sky more than 4 to 5 degrees angular width. LMC lies between Canopus and the South point and can best be viewed after 9 p.m, while the SMC (3 ½ deg across) lies similarly between Achernar and the South. The third visible galaxy, Andromeda Galaxy, is the farthest object seen with the naked eyes at more than 2 million light years away. It can be seen in the north skies, above Cassiopeia and can be seen as a fuzzy patch of light.
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UNIVERSE YOURS TO DISCOVER