September 2011 Night Skies over Tanzania
September 2011 Night Skies over Tanzania
After a long period of quiet on the planetary front, the sky is now waking up to some significant changes that will bring in two of the brightest jewels of the skies – Jupiter and Venus. For some time now, Jupiter has been seen as a mysterious bright light in the East in the midnight or late evening skies. However, by September 15, it rises in the East by 9 pm.
In western sky, soon after sunset, we will be seeing the brightest star, Venus, as an evening star. We will be in the company of these two bright stars at the opposite sides of the sky for several months - Jupiter for the next 6 months as it slowly crosses the sky from East to west, while Venus will adorn the west for the next 8 months.
More significantly, this month we are saying farewell to Saturn which has been our evening companion for the past six months. By the end of this month, Saturn will be too low to be seen in the glare of the sunset use these remaining few days to catch a view of this ringed gas giant.
To understand what happens when we lose a planet to the western Sun, we can use our knowledge that all planets mover around the Sun in orbits that all lie in one flat plane. As the planet moves in its orbit, there comes a time when it takes a position where the Sun comes between the Earth and the planet, hence the Sun blinds our view of the planet.
The Milky Way stretches as a band of numerous stars across the middle of the evening sky, passing through the Southern Cross in the southwest, through Sagittarius overhead, to Cygnus in the northeast. The portion of the Milky Way close to Sagittarius appears as a cloud that is not a real cloud but nebulae of dense interstellar matter that is hiding from our view a powerhouse that is a supermassive blackhole at the center of the Milky Way galaxy.
The Scorpio constellation can be clearly identified by its namesake the scorpion and can be seen high in the western sky. The eastern sky has two “birds”; one to the northeast, where you will see the Cygnus with its body and wings making a wide cross, while in the southeast you will see the smaller bird Grus with its head twisted sideways. Try to become familiar with the brightest stars by their names and relative locations. Enjoying the sky will not be as overwhelming as it might seem
23rd September is the day of Equinox when the length of day and night will be equal throughout the world. On this day, the Earth’s equatorial circle is in the same plane as the Earth’s orbit. Hence the Sun is exactly overhead at midday for all places on Earth along the equator. You might ask what happens at the poles, where normally it is either all day long or night all day long? At Equinox, at the poles, the Sun remains at the horizon and shifts slowly along the horizon from East to West from morning to evening. It never rises nor does it set – it is dawn (or dusk) for the whole day!
An interesting situation about International Space Station (ISS) is that for the whole of this month, until the middle of next month, the ISS will only be seen from our part of the word in the early dawn skies. Amazingly, after mid October, for nearly a month after that, it will only be seen in the early night skies. The first good evening opportunity of observing the ISS comes on 17th October when it will rise in the southwest at 5 minutes before 7 pm and and sets just before it reaches east at 7 pm. For more details and refined, accurate times, visit www.heavens-above.com