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What is Ison?

Ison is a comet which was discovered on the 21st of September 2012 by two astronomers called Vitali Nevski and Artyom Novichonok from Russia.

It’s been a long time since I was at school, remind me what a comet is again?

A comet is a large chunk of ice, dust and rock hurtling through space. Imagine making a snowball out of the slush you get at the side of the road during winter and you'll get the idea!

Why is Ison causing so much fuss?

Ison is what's called a "sungrazing comet" basically this means as it travels through our solar system it will pass close to the sun. As it gets close to the sun it will become heated by the sun and start to vaporise which creates the characteristic comet tail. The closer Ison gets the brighter and more dramatic the comet will become. Due to Ison's path and size, it is predicted to produce one of the most spectacular astronomical shows in living memory!

How big is Ison?

Judging the size of comets is tricky at best, but the current estimate is about 5km (3 miles) in diameter. This estimate comes from data obtained by NASA's Swift satellite, which has been watching the amount of debris (dust and ice) that is ejected from Ison as it travels through space. 5km sounds big but to put this in to perspective the Hale-Bopp comet of 1997 was 30km in diameter! The comet itself is not the main attraction for most people, its the tail which steals the show and this is currently 3700km (2300 miles) long and growing as it gets closer to the sun!

So should I be scared? 

No. Ison presents no risk to the Earth or anyone on it. There has been lots of rumor's about impending doom, far too many to list here so we have a dedicated page to put your mind at rest titled "Should I be scared" which you can find by clicking here.

When can I see Ison?

Comets are not like shooting stars, they don't streak across the sky before fizzling out, so you don't need to worry about blinking, Ison will be visible for weeks not seconds! Below is a quick reference guide, check out our "how to see Ison" for full details on how, when and where to view Ison.
September: During September will need a large amateur telescope to view Ison.
October: During October you should be able to see Ison with a decent pair of binoculars, or basic telescope.
November: Ison will be visible to the naked eye towards the end of November with the 28th being predicted to be the most spectacular due to it being at its closest point to the sun. 
December: Come December we enter the unknown, due to the gravitational force of the sun Ison may well be torn apart. If Ison survives then during the start of December she will have positioned herself to close to the sun for easy viewing but with a bit of luck, may still be visible just before sun rise. By the end of the month Ison will have completed the trip around the sun and will be heading back just in time for new year’s eve when she will be right above us, over the north pole with a newly energized  and hopefully even more dramatic tail. 
January: Come January and some people may be suffering from comet fatigue, but Ison has saved the best for last! Around the 15th of January the earth will pass through Ison's tail made of fine dust and ice. This will produce spectacular meteor showers, but it is the finer dust that does not burn up which will produce the main show. As this dust enters our atmosphere it will cause noctilucent clouds, one of the rarest and most beautiful clouds to form. But her crowning glory, her swan song, will be the colours that are produced by the suspended dust particles in the upper atmosphere, reds, oranges and purple will light up our sky during the early evening like a psychedelic dream sequence!
: As Ison heads back out away from us we expect Ison will only be visible with binoculars again.
 Just like September she will only be visible with an amateur telescope, but don't despair as one comet leaves, another appears! (more info to follow)

Where can I see Ison? 
Ison will be visible from all over the globe, but the northern hemisphere will get the best, and longest view. We recommend finding a dark place to view from, away from the city and the light pollution. Hills in the countryside are always a good place for astronomy, above the low level air pollution. It is worth doing a bit of reconnaissance or "reccy" to find a good spot.
The position in sky will change, it is moving object after all! You can check out where to look in our "How to View Ison" page which will be regularly updated as we track Ison across the heavens.

Why is it called Ison? 

Ison is named after the International Scientific Optical Network, the organisation where it was discovered. Normally a comet would be named after the astronomers who discovered it, but on this occasion the media nicknamed it Ison  and the name has stuck, which is unfortunate for Vitali Nevski and Artyom Novichonok who first discovered it! Technically Ison should be called "Nevski-Novichonok comet" 
Ison is not really the name of the comet at all, just a easy to remember nickname. You may know that animals have two names  a common name which we use every day like "Tiger" and an official scientific or "Latin" name like "Panthera tigris". Comets are just the same, they have their scientific name known as its designation and a common name. Isons real name or designation is C/2012 S1 catchy or what!
C/2012 S1 might sound like a Starwars character but there is a reason for the name.

The letter C is given because it is non-periodic (not a regularly appearing comet like Halley's comet).
The number 2012 is simply the year it was discovered.
The letter S is given to to indicate when during the year it was discovered, a comet discovered between the 1st and 15th of January are given the letter A, from 16th to the 31st they are given B and so on. Ison was discovered on the 21 of September so got the letter S.
The Number 1 is shows it was the first comet to be discovered in "S" period (16th to 30th of September)

How fast is Ison?

Ison is moving fast! As of September she is traveling at approximately 107826 kph (67,000 mph), at this speed it would take Ison just 10 seconds to travel the entire length of the M1 motorway! 
But that's not the whole story, Ison is accelerating. As the comet gets closer to the sun, the effect of the suns gravity is stronger and will cause Ison to speed up. In December when Ison reaches the sun, the sun will "slingshot" her back out into the solar system at tremendous speed. Remember when you were a kid running up to a lamp post, grabbing hold of it and being swung round? Remember how you suddenly speed up, well swap the lamppost for the sun and you for Ison! (If you don't remember doing it, go and have a go now!)
When Ison goes through this slingshot around the sun we expect her to reach speeds of up to 1,359,895 kph (845,000 mph)! At this speed the M1 would take just 0.8 seconds, it is rumoured that Jeremy Clarkson has been seen building a giant harpoon to try and capture Ison.......

Where did Ison come from?

We believe Ison came from the Oort cloud. Our solar system sits inside a large ball shaped cloud of ice and rocks. This is the Oort cloud and is generally considered to be the boundary of the solar system and the birth place of most comets. 

You may notice on the picture above that the cloud has two parts, the inner cloud and the outer cloud. Imagine a football with a dinner plate inside. The outer cloud is where we think Ison came from. The Oort cloud contains trillions of frozen objects, mainly water, ammonia and methane.
The edge of the Oort cloud is about one light year away from the sun, around 22,5000,000,000,000 km (13,950,000,000,000 miles) and at this distance the effect of the suns gravity is very weak. It’s thought that the gravitational effect from our neighbouring stars dislodge chunks of ice and push them in to our solar system where they become comets, like Ison. Very little is known about the Oort cloud in fact most of it is theory, we have yet to send a space probe there! 

What is Ison's mass?
Just like size, it's not easy to work out the mass of comets! Many astronomers are reluctant to even take a guess, but we will! We have estimated Ison to be 3,175,146,590,000 kg. This estimate was reached by a mean average of estimates from 11 BCRS members. All the estimates were within a 9% range, so we are quietly confident with its accuracy. That said, new data is coming in daily so we might revise this figure in the future, but we would be surprised if it was by much! 

How close to earth will Ison get?
At its closest point Ison will be 69,000,000 km (39,900,000 miles) from earth on the 26th of December.

What is Perihelion?

Perihelion is term we use to mean that a comet has reached its closest point to the sun. Comet Ison's perihelion is on the 28th of November at approximately 23:00 GMT when she will pass the Sun at a distance of around 1,200,000 Km (800,000 miles)

What is A.U?

A.U is a measurement of distance, and stands for Astronomical Unit.
A.U is the distance between the Earth and the Sun which is 149,597,870,700 km (92,955,807,273 miles). So if you see Ison's distance from earth as 2.0 A.U this means it is twice as far away as the Earth is from the Sun. 

1 comment:

  1. Got an image of the Stig driving a Landrover while Jezza leans out back firing harpoons at the sky LOL