March 2010 Night Skies over Tanzania
March Night Skies over Tanzania
Dr Noorali T Jiwaji
ntjiwaji at yahoo dot com
On Februry 27th, a Richter scale 8.8 magnitude earthquake, of astronomical proportion struck Chile, the eighth strongest earthquake ever, causing the length of the day to be shorter by 1.26 microseconds (a microsecond is one millionth of a second). This may not seem too much but in this age of high tech communications using satellites it can make a big difference in locating one’s position on Earth. It is a good thing that such earthquakes are rare.
March is a month for worldwide monitoring of our increasingly murky skies. The problem of light pollution is already at plague level in modern economies. This is one area where the less developed economies are better off. Unnecessary light leaking upwards into the atmosphere eats up precious electric energy while at the same time blanking out sparking stars in the sky with a thick fog of light that we call light pollution. The Globe at Night project mobilizes millions of amateur star gazers to measure light pollution in their area and report it to a central database. This is the fifth consecutive year that this project has been undertaken and with more and more ordinary people taking part. Do your bit and let us show how good Tanzania’s skies remain and fight increasing pollution in our cities. We want to keep our skies clean and dark for our coming generations to enjoytheir wonders.. Moreover, this will attract astro-tourists and exploit this untapped natural resource of the dark skies above us. Visit http://www.globe.gov/GaN/ and follow the links and see my explanations here to know how to measure and how to report your measurements of the degree of light pollution affecting your area. We still have four days, until Tuesday March 16th, to participate and submit your report online. From Africa there are only very few results being reported so do your part and contribute to our knowledge of the state light pollution of our night skies.
March is the best time to see the splendour of the skies since we are very well positioned to view the best of the southern skies, which have a far higher concentration of stars than our northern brothers where light pollution worsens their plight. Find a location where your eyes are shielded from bright lights around you. The Milky Way stretches as a band of dense collections of stars from northwest to southeast. We can see the two brightest stars in the sky, Sirius and Canopus, which you can locate using the star map. The constellation that is easiest to recognize is Orion with its huge rectangle taking up a large part of the over head sky, around 8 pm. We use this constellation for measuring light pollution in our areas. Once you have oriented the sky map with the sky using these stars and constellations and the compass direction shown on the map, you will be able to follow the rest of the constellations and stars marked on the map. The middle part of Orion is an area known as the ‘Sword of Orion’ contains the most beautiful collection of bright interstellar dust or nebulae. Even with the naked eye you can see a patches of nebulous clouds. One of them, the ‘horse head nebula’ is very prominent and looks just like its namesake. Of course you would need a telescope to make out the a horse shape.
There are plenty of deep sky objects that you can observe with the naked eyes. Among these is the Pleiades star cluster, also known as ‘seven little sisters’. It is an open cluster of newly formed stars embedded within bright interstellar matter where new stars are still forming. Another similar cluster is the Hyades cluster in the constellation Taurus near its red giant star Aldebaran. The Southern Cross (shaped like a kite), is now easy to view and is used to tell south using its long diagonal, which points southwards. An area close to the Southern Cross contains material that is not bright, so we see a patch of darkness within a region of bright stars, hence its name the ‘coal sack’.
Among the planets, Mars shines brightest almost over head near the Gemini Constellation as shown on the map. Saturn is at opposition (opposite side to the Sun), rising in the east as the sun sets, and can now be enjoyed in the evening skies for the next six months, to view its ring system through a telescope. Venus enters the sky in the west. At the moment it is 11 degrees above the setting sun but the elevation is increasing day by day. Take it as a challenge to find out how early during this month you can make out the bright jewel peeping from behind the sunlit skies in the west. Venus will be our bright companion for the next seven months in the early evening western skies.
The Moon is in its New Moon phase on March 16th, and on the 25th a half moon will be close to Mars. This is the best time to view the moon, since its craters are vividly clear when viewed through a telescope. At this time, long shadows are cast on the moon’s craters due to the low sun there. On the 29th an almost full moon will be close to Saturn.
The Equinox – meaning equal days and nights, is on March 20th, technically called vernal equinox when the sun crosses the equator from its southern position and moves northwards towards the Tropic of Capricorn. Day and night will be equal in length throughout the world on March 20th, and the sun will be exactly overhead for people living at the equator. Since we are south of the equator, the sun is overhead at our locations several days earlier. For Dar es Salaam, the sun was overhead on March 3rd.
The ISS, International Space Station’s bright, stately slide across the evening skies can be enjoyed on March 27th and 29th . On the two days it will appear from the north western horizon at 19:25 and 18:40, respectively soon after sunset. On the 27th it will suddenly disappear from view when it is in the overhead skies as it disappears in the earth’s shadow at 19:30 at a height of around 55 degrees. On 29th it will move slowly across the whole sky rising to a height of about 60 degrees, and go down in the south east horizon at around 18:45. A more challenging satellite to observe is the Lacrosse Rocket on March 16th It will appear as a tiny point like star moving gracefully across the sky rising from the North at about 19:10 and setting in the South after a slow glide across the sky passing close to the red giant star Aldebaran in Taurus. It will set in the south around 19:20. Enjoy the skies and hope that the rains bring relief from the heat but part at night to allow us to get pleasure from the spectacles in our skies.
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