NOVEMBER 2009 NIGHT SKIES over TANZANIA
By Dr. N. T. Jiwaji
ntjiwaji at yahoo dot com
Click on image below to get larger Sky Map for November
Click on image above to get larger Sky Map for November
The Leonid meteor shower will be seen from around the middle of this month with the peak expected on 17th November. The best time to observe will be after midnight. The streaks of light will appear to come from one region of the sky (called the radiant) in constellation Leo which will be rising in the east after 1 a.m. (see picture, from stardate.org). Due to the absence of the moon in the skies during those days (new moon is on 16th November), we expect to see nearly 100 meteor showers per minute or about two every minute. The peak of the shower should be at dawn on 17th when the Constellation Leo will be overhead and when the shower can turn into a storm of 500 per hour which is around 10 every minute; this is huge!!
Meteor showers from part of more than 1000 tons of material that falls onto the earth from outer space every year, mainly in the form of tiny dust particles collected by earth as it hurtles through space in it orbit around the sun at an incredible speed of more than 100,000 kilometres per hour. Besides this, the earth also rotates in its orbit every day at a speed of nearly 1000 kilometres per hour at its midriff (equator). The space through which the earth moves is not as empty as one might think. Dust, particles and other bodies in its path will all be swept up by the earth. The outer space is full of dangers even to satellites orbiting earth.
During meteor showers the earth passes through the debris left behind by a comet. This month’s Leonid meteor shower is attributed to the comet Temple-Tuttle that comes near Earth every 33 years, the last time in February 1998.
Due to the immense speed of the earth, the debris in its path collides with the earth at an enormous speed and can do a lot of damage. However we are protected by our atmosphere which slows most of this material by friction with the air molecules, which causes the fragments to heat up. If the material from space (called meteoroids) is even the size of a speck of dust, the heat due to friction is enough to make it burn and light up. From ground we see this as streaks of light which many people think are falling stars and hence their common name. Astronomers call “falling stars” meteors. When bigger fragments hit the earth, they can produce spectacular shows as glowing fragments explode and produce what are huge flashes of light called boldies. Most of the particles from space will be vaporised upon impact with the atmosphere by the immense heat and will not reach the earth’s surface, but a few of them especially those which have a metallic (mostly iron) content will not burn up completely and will fall onto earth as meteorites.
The streaks of light that we call meteors or by its common name “shooting stars” always appear to originate from single point in the sky which for this shower is in the constellation of Leo, hence its name “Leonid meteor shower” (see figure, which is from stardate.org). Since the meteor activity is unpredictable and there is a small chance for a much bigger rate due to the uneven distribution of the comet debris whose particles enter the earth’s atmosphere to produce these displays that evoke deep awe and wonder.
Jupiter is a planet that you cannot miss in the evening skies shining brightly overhead. The Moon will come closest to Jupiter on 23rd November while it is almost half phase. New Moon is on 16th, first quarter on 24th, Full Moon is on 2nd December while last quarter will be on 9th December.
Rising in the south east at 9 p.m is the second brightest star in the sky, Canopus which can now be seen from this month onwards. It can be seen at the same time as Sirius and is one of the jewels of the southern skies since it can hardly be enjoyed from the northern hemisphere because it is always low, close to the horizon. It is also a very bright star well removed from other bright stars so it is often used as a reference beacon by spacecrafts on voyage to outer planets.
Three visible galaxies can be seen in the early night sky for the next few months. Two of these, the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC) are members of our local group which form a trio together with our Milky Way galaxy. Both Megallenic clouds are once again the preserve of the southern skies since they are so close to the south point. The both have irregular shape and cover a wide area of the sky more than 4 to 5 degrees angular width. Even on a relatively dark night you can make them out with the naked eyes as large fuzzy objects against a dark background. Try to catch them first using a pair of binoculars.
LMC liese between Canopus and the South point and can best be viewed after 9 p.m, while the SMC (3 ½ deg across) lies similarly between Achernar and the South. These two galaxies are about 50,000 light years away from us.
The third galaxy visible to the naked eyes at this time is the Andrdomeda galaxy, which, at 2.2 million light years makes it the most distant object that can be seen unaided. It lies in the northern hemisphere and is well high in the sky by early evening. It can be seen close to the Square of Pegasus in position marked ‘T’ in the sky map.
The bright stars marked this month are: A = Fomalhaut, B = Altaír, C = Deneb in Cygnus (the northern bird), D = Vega, E = Achenar and F = Antares, in constellation Taurus just rising in the east. All these are all first magnitude stars. Second magnitude stars are shown in white letters. They are: J = Al Nair in Constellation Grus (the bird), K = Peacock, L = Kaus Australis in the Sagittarius constellation.
The Milky Way band across the sky winds its way from south west to north east, straddling the western horizon so it does not cross the sky. Hence this month most of the sky will appear to have rather few stars because it is well away from the bright band.
The International Space Station (ISS) will be very brightly visible on 30th November and 1st December. Though the ISS does not rise very high above the horizon on these two days, it is a sight worth seeing. The ISS is a football sized station orbiting 350 kilometres above us. From Earth it is seen as a slow moving extremely bright star. On 30th November it will rise from the North horizon just after 7 pm and will go up in the sky by about 30 degrees in the north-east, turning extremely bright. It will set below the south-east horizon five minutes later. On 1st December it will rise just before 7:20 pm from the north-west horizon, go up in the south-western sky by about 35 degrees, and will set in the south-east horizon five minutes later.
The Hubble Space Telescope is another satellite worth watching out for. It passes over our skies several times this month, but the most spectacular is on Saturday 21st November when it will rise from the north-west just before 7:20 pm and will glide slowly to overhead skies. It will set in the south-east ten minutes later. See the website http://heavens-above.com for more details of passes and exact timing and directions. Many other satellites can be identified and observed using information at this site. Enter your latitude and longitude to get the timings for your location (e.g. 6 degrees south and 39 degrees east for Dar es Salaam).
The International Year of Astronomy 2009 is nearly at its end. 400 years ago this month, Galileo turned skyward a simple telescope that he had made himself and he marvelled at the unexpected details that he saw that changed the whole view of our Universe. Many schools and students and members of the public have taken the opportunities provide during this year to experience the amazement of Galileo and wonder about what makes up our vast Universe. We expect even more students and public to look through the Galileoscope, a telescope similar to that which Galileo looked through but much clearer, and enjoy the wonderful sights the heavens offer and in turn use their creative potential to take astronomy and science even further.
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