December Night Skies over Tanzania

DECEMBER NIGHT SKIES OVER TANZANIA

The sighting of earth like planets is in the news much more frequently than the past. The most recent is the announcement of a discovery of a planet the size of our own Earth, raising the possibility of fining life there.

You may be wondering, “Where have these planets been hiding all these years?” You would be justified in asking this question since past discoveries of the “tenth planet” have all been explained as dwarf planets and even led the demotion of Pluto to a dwarf-planet status. Hence instead of having more planets in our solar system we now have only eight.

So where are these earth-like planets? They are in other solar systems around distant stars. The stars that we see in the night skies are actually distant suns, and the planets that orbit them are called “exoplanets” Recent technological advances have allowed us to know more about these exoplanets.

The most recent advance is the Kepler space telescope that orbits high above our Earth’s atmosphere. It is specially designed to detect planets around distant stars by measuring minute decreases in light when a planet orbiting a distant star comes between the star and the spacecraft. This is amazingly sensitive; like being able to recognize an insect crawling across the headlight of a car that is ten kilometers away from you!

More than 700 such exoplanets have been discovered so far, but most of them are giant planets like our Jupiter. Others are either too far from their parent star, and so too cold, or too near to the star, hence too hot, for any possibility of life to exist. However, the “Kepler 20f” planet is the size of Earth and at just the right distance from its star which is almost the size of our Sun. Hence it has excited scientist with expectations of finding life outside our own Earth.

The unusual rains that we have been experiencing over the past few weeks have interrupted our views of the heavens this month. Horizon clouds ruined our lunar eclipse viewing and now the whole sky is often covered with thick clouds. However skies do open up once in a while to reveal the stars beyond.

In our skies that two planets that have been shining their spotlights in the evening skies are Venus in the west and Jupiter in the east. They continue to catch the eye and you are most likely to see them in the gaps in the clouds.

The night skies are beginning to display many prominent constellations in the sky, but to get the most enjoyment out of it this month, watch a bit late in the night. The brightest star in the sky is now quite prominent in the south-east as the neck star in the dog shaped constellation Canis Major (Big Dog). An arch of stars spanning eastwards reaching north among dense collection of stars of the Milky Way begins with Canis Major giving way to the magnificent Orion, the hunter, which in turn leads to Taurus the bull which contains the distinctly visible red giant star Aldebaran. The last two constellations in the arch are Perseus containing the famous variable star Algol and ending with M shaped Cassiopeia in the north. Close to Taurus is the famous star twinkling cluster, Plaiedes, also known as the ‘seven little sisters’. Just off the arch westwards but still close to the Milky Way can be found the Square of Pegasus. The Andromeda galaxy, which is 2 million light years away yet still just visible to the naked eye as a patch of nebulosity in dark skies, lies between the Square and Perseus, 40 degrees above the north horizon.

Among the most easily identifiable constellation is ORION which we see as a huge rectangle laying on its side in the eastern sky. It has two very bright stars at the end of its diagonals: Rigel on the top right and the giant star Betelgeuse sparkling red on the bottom left of Orion. The other diagonal is marked by three stars close together in the middle, called the ‘Belt of Orion’. It is embedded in a dense cloudy nebulosity of interstellar matter which is and active nursery of new stars as the inexorable pull of gravity gathers the pace after millions of years. The nebula in Orion can easily be made out with the naked eye and is breathtaking even in a small pair of binoculars, let alone a telescope.

Among the Zodiacal constellations spanning east to west are Gemini the twins cutting into Taurus, leading to less prominent Aires, Pisces, Aquarius and Capricorn and ends with Saggitarius setting in the west swamped by sunlight. There are also several stars that you should try to identify because they are among the brightest in the sky. In the last half of the month Procyon rises in the south east with Sirus already high and Canopus in the south: these three brilliant stars form an almost straight line and together with Capella also rising in the north east, forms a reasonable right angle triangle.

Plan ahead to watch a very brilliant International Space Station (ISS) as a spotlight that crosses right through the middle of the evening sky soon after 7:15 pm on 10^th January 2012. It will rise in the north west at 7:21 pm and will take nearly seven minutes to cross to the opposite end and set in the south east at 7:28 pm. It will pass close to Jupiter when it is overhead.

Wishing you all a very happy holiday season and fruitful New Year.