NOVEMBER NIGHT SKIES AND COMET ISON
There is a comet in the sky! Will we see it? Comet ISON has been a talking point since its discovery at the end of last year. Further observations pointed to it becoming possibly the brightest comet of all time because it has come for the first time from its origin in the Oort Cloud at the extreme edge of the Solar System, 50,000 times the distance of the Sun. Also, it will turn the corner around the Sun when it is extremely close to the Sun. Comet ISON is currently approaching the Sun and is set to come closest on November 28, when it will be only 700,000 kilometers from the Sun’s surface, well within its atmosphere.
A comet is a compact body of ice mixed with extremely fine dust. The ice melts when the comet comes close to the Sun’s heat and the fine dust is pushed away by the solar wind particles, and a spectacular tail forms. The very fact that Comet ISON comes so close to the Sun can be both a boon and bane. Such a close approach will evaporate most of the ice releasing a huge dust tail that may be seen in broad daylight. Or the heating combined with extreme gravity will break it up making it too small to be seen from Earth. A picture taken on November 13 shows the comet with a clearly visible thick tail, but after three days the tail became three times longer.
Comet ISON is now at 15 degrees above the eastern horizon at dawn and brightening though lowering day by day as it approaches the closest to the Sun on November 28. With a clear eastern horizon you should be able to make it out with naked eyes. Saturn and Mercury are also seen close to the comet. Through binoculars or telescope you may be able to detect its green colour also. After November 28, it will be an uncertain future as the whole world awaits its fate – a comet of the century or fizzled snowball. We keep our fingers crossed. You can follow the progress of Comet ISON at the website: http://www.isoncampaign.org/ and for observations specific for Tanzania you can follow the progress on http:www.astronomyintanzania.or.tz/
In the evening sky, Venus has peaked its height at 43 degrees above the western horizon at sunset and is ready to outshine itself even further as it comes closer to us. Through a telescope it makes a beautiful sight the shape of an ever thinner crescent as days go by. The best crescent can be viewed from the end of the month. On December 5 crescent Moon will provide a beautiful arrangement with Venus in the eastern sky close to each other with crescent Moon below and to the right of brilliant Venus, which itself will be seen as a crescent through a telescope.
By the end of December Venus will have reached its closest to us and in line with the Sun hence will disappear below the western horizon, preparing to re-appear from behind the Sun as a morning star two weeks later.
The Andromeda galaxy, the farthest galaxy (at 2 million light-years away) that we can see with our naked eyes is close to the Square of Pegasus nearer to the northern horizon, while our nearest galaxy, (at half a million light-years), the South Megallanic Cloud, lies at the opposite end of the sky in the south, between Achernar and the south celestial pole. In relatively dark skies, both galaxies appear as fuzzy patches about 4 degrees across (4 fingers held at an arm’s length).
The bright stars this month that are worth knowing by name are: A) Fomalhaut, B) Altaír, C) Deneb in Cygnus (the northern bird), D) Vega, E) Achenar and lastly F) Aldebaran, which is in constellation Taurus just rising in the east. These are all first magnitude stars. Algol in Perseus is a special star because it varies continuously in brightness approximately every three days.
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.
Next Saturday, November 30, the International Space Station will pass brilliantly across the sky from south west horizon from 7:25 pm, towards north east and disappear while still high in the sky at 7:30 pm when the sunlight can no longer strike the space station as it enters Earth’s shadow.