Comet ISON - The comet of the century

We may witness one of the most spectacular sights in the night sky in the next few days for a generation or more.   Astronomers are hoping that from 5th December, 2013 onwards, a comet will appear on the eastern horizon - The Comet ISON.  It is expected that for the whole month of December, 2013, millions of people across the northern hemisphere should be able to see its tail, which is several million kilo meters long stretching across the dawn sky.

 The ISON comet has come from the Oort cloud, a belt of comets on the very edge of our solar system where it has been for 4.6 billion years.  One of the special about the Comet ISON is that it is a "sun grazer".  Most of the comets pass through the solar system every decade, but very few pass through the corona of the Sun.  Comet ISON will do that.

 When the comet passes through the corona of the Sun many interesting astronomers are watching it.  It is not know what will be the effect of the great heat and gravitational force of the Sun on the comet.   But according to Dr. Mathew Knight, from the Lowell Observatory in Arizona, who has been watching the comet for the past one year has worked out three scenarios to explain what ISON will do in the coming week.

1. Scenario One :  The comet could suffer the same fate as Comet Lovejoy which went around the Sun in 2011.  The gravity of Sun pulled one side of the comet's nucleus more strongly than the other side there by stretching the comet apart.  As Lovejoy emerged from the corona of the Sun, it exploded.  Same thing may happen to Comet ISON.  But it depends on its size.  A nucleus of 2 Kms. or under puts a comet at great risk.  Astronomers estimate that ISON is almost exactly 2 Kms. so it is right on the border line of risk. 

2. Scenario Two :  ISON might behave like Comet Encke.  This comet has orbited the Sun about 70 times since it was observed a few centuries ago. The comet is fast using up its ice and gases and is fizzling out.  Even though ISON is going to pass the Sun only onc, Dr. Knight fears that it could suffer the same fate.

3.  Scenario three :  This is the scenario that most of the people are hoping for.  This is what happened to Comet Ikeya-Seki in 1965.  As the comet went through the Sun's corona, the heat ignited the gases deep in its nucleus and a few days after it emerged from the corona, a huge tail has developed behind it.  Millions of people were thrilled by the great event.  

If ISON puts on a stunning display like Ikeya Seki did, it will help scientists answer some of the questions about our origin.  Spectrometry will allow us to analyze the chemical composition of the ices on ISON and from that data, we can work out how the Solar System was formed 4.6 billion years ago.  It is also possible to study its water signature,  to provide crucial data informing the argument about whether our water came to Earth on comets, or accretion from below the planet's surface. There is even chance that scientists will observe the chemical precursors of amino acids which are the molecules which form the building blocks of life.  Experiments in the NASA laboratories shown that these building blocks of life can be created in the hostile environment of a comet's nucleus.  Could comets be the agents which transport these life building blocks across the cosmos??  

You can now follow the comet's progress on the internet.  Let us hope that ISON will be talked about for the years to come - as the comet of the century.  Here are some details about the comet ISON.

 Details of Comet Ison

• Discovered on 21 September 2012 by Vitali Nevski and Artyom Novichonok
• A so-called "sungrazer", it approaches our star at a distance of just 1.2 million km from the surface
• Ison brushes past the Sun on 28 November; the heat at "perihelion" is expected to exceed 2,000C
• The encounter could cause Ison to break up completely, but if it survives, the comet could put on a bright display in the sky during December