October 2010 Night Skies over Tanzania

We are at an exciting time for planets. While the news about a new planet is buzzing the media, old planets are making a big splash. “NEW PLANET DISCOVERED” shouts the news from pages of papers, websites and on TV screens. It is true that a new planet has been discovered, it is not quite absorbed that it is nowhere near us. Planet Gilese 581g is 200 trillions kilometers, or 20 light-years away rotating around another sun out there, which we know as a star.

Though it is thought that there is almost 100% chance of finding life there, we will not be visiting them anytime soon! What is often not mentioned in sensational news stories is that hundreds of new exo-planets have already been found and Gilese 581g is just the first one with conditions so similar to Earth so suitable for life as we know it.

With even newer technologies being developed, the discovery curve is increasing so fast that we are likely to find hundreds of planets that may be suitable for life hence increasing the chance of being able to communicate with them. And all this is in just our own Milky Way galaxy; and there are billions of galaxies out there, so getting someone whom we can make friends with is becoming more and more likely.

To appreciate the difficulty of discovering new exo-planets rotating around another star, imagine a fly crawling slowly across a head-lamp of a car at night ten kilometers away. What amazing instruments these must be to able to detect the fly on that lamp!!

Do not be disappointed if you cannot say hello to someone on an exo-planet soon, because our own planets are blazing across the night skies at the moment. In the evening around 7 pm, two planets at opposite ends of the sky are dazzling and confusing people. One extremely bright star (planet) is setting in the western sky, while at the same time another one with similarly extreme brightness is rising in the east.

The planet in the west is Venus, which is coming ever so close to us at the moment and in the process, since its orbit is inside that of the Earth’s, it is showing its dark backside to us, leaving a thin part of its bright side visible to us as a crescent. On October 9, TWO CRESECENTS will hence be seen, one with the naked eye, the Crescent Moon and the other through a telescope, Crescent Venus! A sight definitely not worth missing and is part of the World Space Week activity celebrated by millions all over the world including us, between 4 and 10 October. Venus sets soon after 7 pm., and will soon disappear from our evening skies only to reappear as a morning star at the beginning of next month, November.

On the opposite end is the huge planet Jupiter, which is closest to us in 50 years and hence extremely bright. It rises slowly as the night progresses and is overhead by midnight and sets in the west the next morning. Through a telescope it is a clearly visible disc with four moons clearly visible spread along a straight line along its diameter, showing that its moons form a mini solar system. The brightness of the planet also allows the orange colour of Jupiter’s cloud stripes. Through smaller telescopes the bands appear gray as objects normally appear in dim light.

An interesting planet to search for those with a medium sized telescope is Uranus, which is within two degrees of Jupiter. Hence you can use the latter as a marker and locate Uranus to its lower left when facing east.

Mars, a planet that is in most people’s attention, again due to wrong information, is not very bright as it moves slowly away from us and is low in the western sky at sunset. Hence it is difficult to make out in the bright glow of the setting sun.

As if the above delights are not enough we have an “ugeni” (visit) of a comet named Hartley 2. You should be able to see it with the naked eye or binoculars near the constellation Perseus throughout the month of October. On October 20th, it will make its closest approach to Earth at a distance of 20 million km). The comet is officially designated 103P Hartley

The Moon was new on 7th and will be a crescent, close to Venus and Mars on October 9 and 10. It will reach First Quarter phase (i.e. half) on 14th and by 20th a gibbous Moon will be close to Jupiter. Full Moon is on October 23 after which it will rise later and later in the night, reaching Last Quarter phase on October 30. It is best to view the Moon when it is in its quarter phases when the half shape forms a clear line between the day and night side on the Moon, where the shadows are longest and hence craters are seen vividly.

The Milky Way stretches as a band of numerous stars across the evening sky, from north in the W shaped Cassiopeia, through Cygnus the large northern bird, on to Saggitarius the archer and the tail of Scorpio. 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.

This is a month of galaxies because if you are well away from city lights you might be able to make out patches of brightness that are made by our closest neighbouring galaxies, the Small Megallenic Cloud which is about 37,000 light years away can be seen close to the horizon towards the south, marked U on the map. The Andromeda galaxy can be seen again close to the horizon in the north, marked T on the sky map. It is a spiral shaped galaxy similar to our Milky Way galaxy and is about 2.2 million light years away. This makes the Andromeda galaxy the most distant object that we can see with the naked eyes. Try to locate these two galaxies using the star map.

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.

The International Space Station will be seen crossing the evening sky bright as the two planets Venus and Jupiter on October 18, 19 and 21 with the best view crossing the whole sky to overhead on October 19 and 21. On 18th it will rise in the south at 6:45:56 pm and hug the south eastern skies low up to 18 degrees and disappears suddenly in the East at 18:49:43 pm.

On 19th it will rise at 7:11:45 pm in the south west and rises to 55 degrees while crossing the sky heading north and disappears suddenly when it enters the Earth’s shadow at 19:16:22 pm

On 21st it again shows a majestically bright crossing from south west to north east, rising at 6:29:44 pm and reaching an altitude of 42 degrees, setting in the north east at 6:35:23 pm. The sun is just gone below the horizon at this time so the crossing will be in slightly lighted sky, so watch out for it in the brightness of the sky.

The sun, on its apparent southward movement will reach its highest elevation in Dar es Salaam on October 11, around noon, when all shadows disappear since the sun reaches exactly overhead in the sky.