[Benjamin]

If we're lucky, then in just a few days' time we could witness one of the most spectacular sights in the night sky for a generation or more.

Astronomers hope that on 3 December a comet will appear on the eastern horizon - Comet Ison.

For the whole month of December, millions of people across the northern hemisphere should be able to see its tail, which is several millions of kilometres long, stretching across the dawn sky.

Ison has come from the Oort cloud, a belt of comets on the very edge of the Solar System, where it has been for the last 4.6 billion years.

What makes Ison so special is that it is a "sungrazer". Many comets pass through the Solar System every decade, but very few go through the corona of the Sun. Ison will do just that.

Continue reading the main story
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
Comet of the Century: A Horizon Special
Its passage through the corona, which happens on 28 November, will be watched with great interest by astronomers across the world.

It's not known exactly what effect the great heat and gravitational force of our Sun will have on the comet.

Dr Matthew Knight, from the Lowell Observatory in Arizona, has been watching the comet for the past year and has worked out three scenarios to describe what Ison might do in the coming week.

Scenario one: It could suffer the same fate as Comet Lovejoy, which went around the Sun in autumn 2011.

The gravity of the Sun pulled one side of the comet's nucleus more strongly than the other, stretching it apart.

As Lovejoy emerged from the corona it exploded. Whether this will happen to Ison depends on its size. A nucleus of 2km or under puts it at great risk. Astronomers estimate that Ison is almost exactly 2km, so it's right on the borderline.

In scenario two, Ison might behave like Comet Encke. This comet has orbited the Sun about 70 times since it was first observed a few centuries ago.

The Sun
It remains unclear whether Comet Ison will survive its encounter with the Sun
It is fast using up its ice and gases and is fizzling out. Although Ison is only going to pass the Sun once, Dr Knight fears it could suffer the same fate.

Then there is the third scenario, the one many people will be 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 had developed behind it. Millions of people were thrilled by the great spectacle.

Comet
Astronomers are hoping Ison behaves like Ikeya Seki, which developed a huge tail after its brush with the Sun
If Ison puts on a stunning display as Ikeya Seki did, then it will also help scientists answer some of the great questions about our origins. Since 1965, telescopes and imaging technology have advanced enormously.

Spectrometry will allow astrochemists to analyse the chemical composition of the ices in Ison and from that data try to work out how the Solar System formed 4.6 billion years ago.

They might even be able 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 our planet's surface.

There is even a chance that scientists will observe the chemical precursors of amino acids. These amino acids are the molecules that form the building blocks of life.

Experiments in the laboratories at Nasa Ames, in northern California, have shown that these building blocks of life can be created in the hostile environment of a comet's nucleus. Could comets be the agents that transport these building blocks across the cosmos?

Everybody can now follow the comet's progress on the internet. Here's hoping that Ison will be talked about for years to come - as the comet of the century.

http://www.bbc.co.uk/news/science-environment-25052236

[Benjamin]

Why is nobody else excited by this?

[Livia]

That is exciting... I'll definitely look for this. First I've heard about it!

[Lee.]

I am excited.. Especially as we've had really clear skies for a while now .. I take it it will be visible first thing in the morning rather than at night?

[user104658]

I'd be excited but I'm in Scotland, and it's in December. The chances of actually being able to see it are probably something like 2%

[MTVN]

We're all gonna die

[Josy]

Watched a couple of documentaries about this the other night, it has to make it past the sun first and they think it might not actually survive because it's heating up so much already.

I hope it does though it will be amazing to see.

[James]

I'd be spectacular if it was a daytime visible comet.

[reece(:]

Times like this I wish I had a telescope!

[Josy]

Originally Posted by reece(:

Times like this I wish I had a telescope!

You will be able to see this without one apparently.

[King Gizzard]

Would be great if it hit the earth and signaled the end of the world

[Josy]

Originally Posted by Nathan

Would be great if it hit the earth and signaled the end of the world

[Jordan.]

Exciting but these things always turn out to be uneventful

[Josy]

Someone on the news just saying they 'think' it's been destroyed by the sun.

[Drew.]

http://www.bbc.co.uk/news/science-environment-25143861

[Benjamin]

Dang

[Shaun]

still not as big a flop as Azealia Banks

[Benjamin]

Originally Posted by Shaun

still not as big a flop as Azealia Banks

Nothing can flop that hard, not even a flaccid penis.

[King Gizzard]

Have the faith evans

[Kizzy]

It wasn't destroyed, was on the news this aft.

[Josy]

Comet Ison, or some part of it, may have survived its encounter with the Sun, say scientists.

The giant ball of ice and dust was initially declared dead when it failed to re-emerge from behind the star with the expected brightness.

All that could be seen was a dull smudge in space telescope images - its nucleus and tail assumed destroyed.

But recent pictures have indicated a brightening of what may be a small fragment of the comet.

Astronomers admit to being surprised and delighted, but now caution that anything could happen in the coming hours and days.

This remnant of Ison could continue to brighten, or it could simply fizzle out altogether.

"We've been following this comet for a year now and all the way it has been surprising us and confusing us," said astrophysicist Karl Battams, who operates the US space agency-funded Sungrazing Comets Project.

"It's just typical that right at the end, when we said, 'yes, it has faded out, it's died, we've lost it in the Sun', that a couple of hours later it should pop right back up again," he told BBC News.

The European Space Agency (Esa), too, which had been among the first organisations to call the death of Ison, has had to re-assess the situation. A small part of the nucleus may be intact, its experts say.

More here:

http://www.bbc.co.uk/news/science-environment-25143861