October Night Skies
October Night Skies over Tanzania
By Dr. N. T. Jiwaji
ntjiwaji at yahoo.com
Two recent stories show how life on earth gives a good idea about what we might find in outer space. A colony of bacteria found nearly 3 kilometers below the surface of the earth show that one type of life can exist independently by itself without other life forms and without any sunlight or oxygen. This raises hopes of single life forms being found in extra-solar planets - that is planets circling other stars. The Venus Express spacecraft which is currently in orbit around Venus is looking towards earth to measure the type of radiation that would come from a place where there is life. If water and oxygen were the only requirements, those have been detected on Venus also yet we know that is the last place that life (as we know it) can exist on Venus because of its extremely hot and sulphurous atmosphere.
If you were up at dawn on 7th October around 6 am you might have seen a brilliant fireball in the north as 3 meter sized asteroid hit the earth and fell on a remote site in Egypt. We had a 19 hour warning on this impact from a space rock. This is the first time that scientists were able to give a prior warning about the impact from outer space. Though the notice was only of 19 hours, it is very significant because scientists were able to predict its time and path accurately. It gives us confidence in our ability to predict strikes of larger objects in the future, which would have much more catastrophic consequences.
Jupiter and Venus are the most brilliant objects in our skies this month. Venus is seen in the west about 35 degrees above the horizon at sunset, while Jupiter is overhead. If you observe the skies a little later, you will see Venus setting by 8:30 pm while Jupiter will be seen still high in the western skies.
Venus shifts its position upwards towards Scorpio constellation and by 20th October it will be in the mouth of the scorpion ready to be “swallowed”. On 31st October, soon after the New Moon on 29th, Venus will form a beautiful arrangement with the crescent moon and the red-giant star Antares in the neck of Scorpio. During the whole month, Jupiter is still stuck in Sagittarius constellation as it now comes out of retrograde motion and resumes it eastwards shift.
Among the interesting constellations, Scorpio is in the west ready to leave the night skies, while Cygnus, the bird spreads its wings in in the north. The Square o Pegausus enters the sky from the east and ushers in the most distant galaxy visible to the naked eye.
The evening sky is worth watching for prominent stars and galaxies. Over the next few months the night sky will show four galaxies visible to the naked eyes. The obvious one is our own “Milky Way” galaxy which we see from inside it as a bright band of myriads of stars and interstellar dust in cloudy patches known as nebulae. The Milky Way band stretches from southwest to north east ending at the W shaped Cassiopeia. It passes through Cygnus, the large northern bird, on to Sagittarius the archer and through the tail of Scorpio and ending at the setting Souther Cross, whose two pointer stars are vertical this month.
Our Milky Way galaxy is immense, about 100,000 light-years across. Which means light, traveling at 300,000 kilometers every second would take 100,000 years to cross from one end to the other! Our closest neighbor galaxy, the “Small Megallenic Cloud” (SMC) 500,000 light-years away is relatively quite close to us. It is visible as a patch of brightness close to the south horizon. Close to it is the “Large Megallenic Cloud” galaxy but is not yet visible this month. Four times farther away at 2 million light years is the next closest galaxy, the Andromeda galaxy, making it the farthest object that can be seen with our naked eyes. It can be seen near the Square of Pegasus close to the north eastern horizon in the early evening. Through a powerful telescope the Andromeda Galaxy is seen as spiral shape similar to the shape of our Milky Way galaxy. Galaxies contain around a hundred billion light stars kept revolving together around a super-massive black hole
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