Dr Jiwaji's Astronomy in Tanzania
Welcome - Karibu
- Tanzania Liaison for the International Astronomical Union (IAU) Commission 46 for Astronomy Education and Development
- Single Point of Contact (SPoC) for Tanzania for the International Year of Astronomy 2009 (IYA 2009)
MAY NIGHT SKIES OVER TANZANIA
By Dr. N. T. Jiwaji
ntjiwaji at yahoo dot com
Dark Skies Awareness
Dark skies awareness day was marked last month on 20th April to act against the disappearing night skies in urban areas. Though the problem is not as acute in Tanzania as in more affluent countries, where most people cannot enjoy the beautiful sights that the night sky has to offer. Our problem is more in the major cities and municipalities which are growing at alarming rates. In most parts of Tanzania though, the night skies remain sparklingly attractive with numerous of stars and nebulae can be seen clearly. One of the most beautiful sights is the dense collection of stars in the Milky Way (our Galaxy) which can be seen stretching at the moment from south east to south west.
On completely dark nights, we should be able to see about 2000 stars with our naked eyes outside the Milky Way band. However in urban areas such as Dar we can see less than 300. This should be a wake up call for us to make sure that lights that we put up outside are directed strictly downwards because any light that is directed upwards is scattered back towards earth by the atmosphere which makes the skies bright and hides the beautiful night skies.
The planets that can be seen this month are Mercury, Mars, Saturn and Jupiter. Mercury is rising fast in the evening skies and is highest on 14th May getting to 22 degrees above the western horizon at sunset. Mar is now seen in the west though its red brilliance is now dimming as it moves away from earth.
Saturn completes its retrograde motion this month coming closest to Regulus in Leo Constellation on 7th May to almost two degrees (about two finger widths apart). From then on it will resume its normal eastward movement in the skies. It is a beautiful object when viewed through a telescope thought its ring shape is getting difficult to make out because we are viewing it along the plane of the ring. This makes the planet look like it has two ears!
Jupiter rises in the East around 10 pm this month but by the end of the month it will rise by 9 pm.
The Moon is new on 5th and Full on 20th. It comes closest to Mercury on 6th just after the New Moon so they should make a beautiful pair but will be a challenge to view just after sunset since both are faint and very close to the bright western horizon. On 10th May the Moon comes very close to Mars by less than 3/4 degree (less than one finger width). On 12th May the Moon is close to Saturn by about 2 degrees.
On 29th May the Moon is close to Antares, the red giant star in Scorpio and though they start by being nearly 3 degrees apart (about 3 finger widths apart) as the pair rises in the east at sunset, by the time the night ends, at 3 am in the morning they will have come closer to nearly half a degree (that is less than half a finger width apart). This should be interesting to see.
4th May is also the peak of the Eta Aquarid meteor shower which can be seen from the beginning of the month. The bright moon will reduce the number of shooting stars that will be observed and you will have to observe it after midnight ot see its maximum effect. Its radiant (the apparent direction from which all the meteors appear to shoot out from) is below the constellation of Aquarius, which rises in the east at that time. The meteor shower is associated with debris left behind by Halley’s Comet and it is one of the meteor showers that can be observed best from our low southern latitudes.
Costellations and Stars
We will see the last of the most recognizable Orion constellation this month, so go out behold it lying low in the west, close to Taurus with its twinkling Pleiades cluster also called the ‘seven little sisters’. However, Gemini, Leo and Cannis Major with its brightest star in the sky, Sirius, are easy to recognize in the mid skies. Towards the east, Virgo and Boots can be recognized by their brightest stars Spica and Arcturus respectively while another constellation that is easy to recognize, Scorpio rises in the east. The south and north directions are also well marked by the southern cross and the big dipper whose stars are used to point out these directions.
International Space Station
The International Space Station (ISS) can best be seen this month on 20th May, but on 18th though it is slightly brighter it disappears into the shadows close to the zenith after rising from the horizon in the south west at about 7 pm and crossing only half the sky. On 20th the brilliant ISS rises again in the south west around sunset and takes 10 minutes to cross the whole sky and sets on the opposite side. For more accurate timing and positions of the ISS visit http://www.heavens-above.com closer to the date of the event.
International Year of Astronomy - The Universe, Yours to Discover
Mwaka wa Kimataifa wa Astronomia - Ulimwengu Wote, Wako Kuuvumbua