You know, we have no idea what's gonna happen to this comment, but we know a few things about it that indicate that it might well put on quite a show called Comet Ison, and it's from a long way away.

It is a kind of comment that his never ever been in our solar system before, and it never, ever will be again.

It's a one time visitor, and not only that, but it's going to pass very, very close to the sun.

It's called a sun grazing comment, and those two facts together make it quite interesting.

Comments can orbit the sun just like the planets do, but they tend orbit in a different way, So I can I could make a little model of the solar system here, got got our son.

This is absolutely not to scale with most of the planets orbit in a plane, and they tend to have orbits that are technically ellipses.

Those orbits are governed by Kepler's laws of orbital dynamics, which are very well known, happened known for hundreds of years.

But comments tend to do something very different.

So instead of a slightly squashed circle, they can have orbits that are very, very elliptical, sort of the shape of this whole table.

And they don't have to be located in the plane of the ecliptic, the same plane that all of those planets do.

They could be tilted up at quite high angles.

They could be oriented in all sorts of different directions.

They can have orbits that take only a few years or a few tens of years took around the sun.

They can't orbits that take tens of thousands of years and they get flung way out into the outer solar system and beyond.

And then back in again, this special kind of comment is visiting us from the Orc Cloud.

The Orc Cloud is probably the source of a lot of these very distant orbiting comments, and it's probably, we think, a remnant of a leftover bit of when the solar system, formed from a big disk of debris on material that got puffed up and sent out, got sent out.

So far that is, actually, we think, probably billions of tiny little icy objects in a cloud about a light year in radius that's 1/4 of the distance away from the next nearest star.

That's way, way beyond where the actual planets those objects probably stay out there millions and millions of years.

But they're very vulnerable to being perturbed and bumped around a bit.

So a passing star or the gravitational field of the Milky Way might have nudged one just enough.

That's it.

It left the Orc Cloud, and it has plunged all the way into the inner solar system.

But it's not on elliptical orbit.

It's not this closed score circle.

It's on a hyperbolic orbit.

It's following a hyper Bella that will take it in towards the sun, whip it round the sun in a sort of slingshot manner.

This is exactly the kind of orbit that we send spacecrafts on around Jupiter to slingshot them out into the outer solar system, and then it's gonna fly back off way, and we're never gonna see it again.

What will happen to her?

Oh, well, it'll it'll It'll experience very exciting and fun things around the sun.

It may or may not make it around the sun as we can talk about in a minute, and then it'll just it'll just head back out, become cooler, become.

If it survives, it'll it'll just wander off back into the outer solar system.

The generic name for a comment is known as a dirty snowball, which kind of reflects its composition.

It's rock, it's ice.

It's some organic compounds and some gas all mixed up together.

When it's out in the cold reaches of the outer solar system, it's just a lump.

It's not doing very much, but as it plunges in towards the sun, it gets gradually heated, and then interesting things start to happen.

Material will vaporised off.

Um, what you start off as a very solid if would be nucleus that might be meters or kilometers across.

It will gain an atmosphere called the coma, and that will be puffy and gay, cious and big.

And then what we think of with the comment on where they get their name is from the tales that form.

You can actually get two kinds of tales.

So if this is the coma, this is the nucleus, plus the outer atmosphere of our comment.

This comet is coming into the sun, and the material is now being heated, and it's starting to stream out behind it.

And it's forming this beautiful tail that is probably largely made up of dust.

And that's what we tend to think of when we think about beautiful comet streaking across the sky.

And, in fact, the origin of the word comet refers to something with hair.

So these air Harry objects, if you like, and this column this tale.

This is an important point.

It's not.

It's not.

Following the direction of motions is not streaming out behind the comet in the sense that my hair might be blowing behind me if I'm running, Um, it's it's it can actually follow kind of a curved path as it gets left behind.

In this orbit, you can have kind of a curvy tail.

That's not the only kind of tail you have.

The second kind of tale is called an ion tail, and this is the interaction of particles that are being pushed off the comet's nucleus, and they're interacting with charged particles from the solar wind.

And so if this is the sun here the solar wind is pushing Thies, this is this ion tail out in a straight line behind the comet and this is formed from interactions between material coming off the comet gas and the solar wind, the stream of charged particles that is going out in all directions from the sun.

And so this solar wind is gonna push this ion tail back and it's gonna be in a straight line.

The ion tail is always gonna be pointing away from the sun because of the solar wind.

The dust tail is can be slightly curved and is gonna streak out behind the comet in its orbit.

At an interesting thing about the dust tail is that that material can stay there, orbit around the sun for a long time, and our orbit on Earth can intersect that remnant of dust.

And when that happens, that's when we see these periodic meteor showers every years.

The persons in August is a famous meteor shower that happens every year.

And that's because every year at that time, the Earth's orbit sweeps through this leftover material from a comet and those tiny little particles burn up in the atmosphere and give us a great meteor show.

Comet Ison was discovered in September 2 2012 and as its orbit was calculated, this is way out by the orbit of Jupiter's.

It was before it had any sort of spectacular tail or anything like that.

And as observations were taken and its orbit was plotted, we started to realize that it was going to be one of these sun grazing comets.

And in fact, it was gonna come within about 1.8 million kilometers of the sun at its perihelion, its distance of closest approach That's three times the solar radius.

That's really really close at the time of filming, I think nine different spacecraft have actually observed and will continue to observe comet ison as it approaches the inner solar system.

So we're early November now 2013 were a few weeks away from Para Healey in the big question is what's gonna happen to Dyson?

It may well be that it disintegrates before it even gets close to the sun.

That's a possibility.

Once it gets round, the sun it has to contend with temperatures of 5000 degrees has to contend with the title gravitational field of the sun which might may, well tear it apart.

It's gonna be traveling at 400 kilometers per second at that time.

To put that in perspective, if we were to travel from the University of Nottingham campus here, not in him to the university, not in campus in Ningbo, China.

If we did it that fast, 400 kilometers per second, it would only take us 23 seconds.

So it's gonna whip around the sun.

And if it makes it out the other side, that's when we may well be in for a treat, because then it will feel the full force of the solar wind of its orbital journey.

And that's when it may well brighten.

Very, very bright may be visible to the naked eye.

May, if we're lucky, have a beautiful long tail on dhe.

We will be able to observe it very well.

It's not the most romantic of names.