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What I intended to do with this talk was working on the basis
that it would be clear outside.
What I will advertise is that we have an astronomical society here at the OU,
and the "OU Astro soc" which is open to members of the public,
you don't have to be a member of the Open University to come along.
We meet on the first Tuesday of every month.
Next month we're going to an Institute of Physics lecture
here at the Robert Hutt Building,
but normally we have our meetings still on campus,
just a bit across the other side of campus.
If you're interested in joining us, just drop me an email at some point.
But if you're interested in observing, meeting like-minded people,
and you're not in Milton Keynes, find your local astronomical society,
it's a wonderful thing.
You get people who are interested,
you get regular speakers observing sessions.
There is also a Milton Keynes Astronomical Society.
I don’t know them personally but they're also there,
and they probably meet more often.
So, there are opportunities there if you want to go out
and learn more but don't want to do a course,
that you'll be able to go and use telescopes and things like that.
But, onto the talk.
This is something we don't see very much these days, the sun.
It's a nice little start.
But what we're interested in is what happens when the sun goes down.
However, there is a very active field of astronomy that is observing the sun,
looking for sunspots, solar flares, prominences,
and you can get very special telescopes that allow you to look at the sun directly.
But, these are the kind of things you've got to pay quite a lot of money for,
and they're specially designed.
The one caution I wanted to give before I move on to anything else is,
never ever directly look at the sun with the unaided eye,
binoculars, a telescope, it's really very bright and very damaging.
But, if you do things right,
you can project the sun – if you have a telescope,
put a piece of paper behind it,
far enough away that you don’t set fire to the paper –
I nearly set fire to a telescope one time doing that,
it wasn't a good thing at all, people were a bit unhappy with me.
I was 13 and felt it was a good idea –
but you can project the sun and see the sunspots and things like that,
it's something that's worth looking up on the Internet, it's very cool fun.
But, when it's getting dark of an evening, the first thing you'll see – well,
often you'll see the moon, which is fairly easy,
but at the moment, the first thing you'll see,
very low down in the south-west, just after sunset, is Venus,
which is surprisingly bright once you see it.
I mean, it's the kind of thing,
it looks like an aircraft coming in with its headlights on, almost,
it really is that bright.
Over the next few months, you'll see Venus
getting higher in the sky over time in the west and south-western sky,
getting brighter and brighter as it moves away from the sun in the sky,
and that's a very good thing to look at.
If you find Venus and have a look at it with a pair of binoculars
or with a telescope,
you'll see that, just like the moon, it shows a phase.
And that's because Venus is closer to the sun than we are,
so, it's on the inside,
so we see the unilluminated side that's nearer to us,
and when Venus is almost directly between us and the sun,
we see a very thin crescent, just like the moon is showing here.
And then, as it moves around, you see the phase fill up and fill up,
until just before Venus goes behind the sun,
as we look at it, you see it almost full.
And it appears in the morning sky and goes backwards full through to present.
That's well worth looking for if you've ever got a pair of binoculars.
But, once again,
wait until the sun's below the horizon before you start looking like that,
unless you can make sure the sun is nowhere near your eyeline,
if you hide behind the building.
You can just about see Venus with the naked eye in the daytime,
but you need to work out where to look.
I've done it once, it's very cool once you realise that that is actually a planet.
Moving on, as it gets a bit darker still,
and you've probably seen this many, many evenings over the summer,
that's Venus for scale, this is Jupiter.
A bit fainter, still, in theory, visible with the naked eye in daylight but,
in practise, very, very, very hard to do.
That's the bright thing you've seen low to the south all through the summer,
very, very bright, hanging there in the constellation of Sagittarius.
That's the second thing that's visible, ignoring the moon,
as it gets darker and darker.
Over the next few months,
you'll see that moving towards Venus in the sky,
as Jupiter gets closer and closer to the sun in the sky and Venus pulls away.
And so I'm reliably informed, at the end of November,
start of December,
Venus and Jupiter will be very close in the sky after sunset
and be very, very pretty.
And, on 1st December, if you're out just after sunset,
you'll be able to watch Venus reappearing from behind
the thin crescent moon which passed in front of it,
next to Jupiter in the sky, forming a little triangle.
It should be really, really pretty.
There are two other planets that are visible at the moment,
although you need, kind of, binoculars, generally, to see them.
On the left you have Uranus, on the right, Neptune, here.
These are pictures taken with the Voyager 2 spacecraft
that flew past them in the 1980s.
They're pretty much, to the naked eye,
through a telescope or through binoculars,
unimpressive little discs,
but they're quite pretty because they do hang there against the stars
and they have a visible disc,
but you do need a telescope or binoculars to see them.
But, if you go down to your local astronomy society,
I'm sure you'll be able to find someone who can point out where they are.
If you've got really good eyesight
and you go somewhere away from all the street lights and light pollution,
Uranus is just visible with the naked eye, as a faint star.
And the way that you could check that what you're seeing really is Uranus
is find it and then look again a week or two later,
and it should have moved, just a little bit,
but you can see its position move with respect to the background stars.
So, as it gets darker still and the stars start come out,
with this being late summer, early autumn,
these three bright stars are very visible to the kind of south-west.
They form a very big triangle on the sky which is kind of anachronistically
known as the summer triangle, and they are really bright and visible,
and they're a very good way to navigate your way around the summer
and autumn sky.
The brightest of the lot is a star called Vega,
which if any of you have seen the film Contact or read the book,
it plays a prominent role there.
It's fairly nearby as stars go, the light from it takes about 26 years to reach us,
so, the light you see from Vega the next time you go out observing
was emitted a few years after I was born and has spent all the time travelling,
it's very nearby for a star.
But it's quite a bright star,
it's actually the fourth brightest star in the sky.
And around it you've got the constellation Lyra the Lyre,
which is this quadrilateral shape, and that star there.
Now, Vega's really interesting from, kind of, life elsewhere point of view,
because it was the first star that was ever observed
to have a disc of debris around it.
There was a satellite in the 1980s called IRAS,
which was the Infra-Red Astronomy Telescope,
and looked at Vega and saw, basically, a lot of dust,
which was the first time we'd seen debris, dust, around a star,
other than our sun.
Now, it's probably too young to have inhabited planets like ours,
it's a very young star, but that dust could well be in the process
of either forming planets or being battered around
by the Jupiters of that system to make it collide into each other, to see.
So, that's quite interesting, that we've actually seen dust around that star.
For comparison, the bright star here,
Deneb, which is at the tail of the Swan in the sky,
looks a little bit fainter than Vega in the sky, but is actually hugely,
hugely brighter in reality.
The difference is, the light from Vega has taken 26 years to reach us,
very much a near neighbour,
the light from Deneb has taken nearer 6,000 years,
it's much, much further away.
And Deneb's actually one of the very brightest stars in our galaxy.
We see it from so far away just because it's so incredibly powerful and luminous.
The Swan, the constellation, this is the tail,
you've got a long – this starry barrier is the head, effectively,
a long outstretched neck and wings swept back here.
Much as it doesn't really look like a swan,
it's about as good a fit between a constellation
and the thing it's meant to represent as you'll see in the sky.
And when you're under a sky like this and you can see millions of stars,
it's hard to pick out.
If you're looking at dusk and the stars are starting to come out,
that's the best time to find and identify the constellations,
because you only see the really bright ones.
This star here is really pretty, it's a star called Albireo,
which is a double star.
There are two stars moving together through space orbiting one another.
And that's a particularly good example
because the two stars have very distinct different colours,
and I'll show you that in a moment.
Firstly, though, at the bottom end of the Lyre of the Harp,
you've got these two stars here,
and about a third of the way between them,
much too faint to see with the naked eye, is this object.
Now, that doesn't look a very impressive picture
but that's a picture I took with the telescope, just down the road a bit.
This is something called the Ring Nebula.
If you can afford a slightly better telescope,
you get something like this.
This, off here, is a little spiral galaxy,
which I can give you better examples of later.
The Ring Nebula though is spectacular.
To give you an idea of the scale of this in space,
for light to travel from here to here would probably take a year.
And this is the remains of a star that was very much like our sun,
reached the end of its life, and very gently, very sedately,
puffed off its outer layers like a smoke ring.
And they've continued to expand out into space
to make this lovely planetary nebula. Isn't that nice?
In the middle you have something called a white dwarf,
which is about the size of our Earth but about as massive as our sun.
It's very dense.
One teaspoon of a white dwarf would weigh as much as a big massive truck.
So, a very dense, very small object.
Going back to this, Albireo, the colourful double star, it's like that.
Now, what I would caution is,
for most of the pretty pictures you see on the Internet,
most of the pretty pictures I'll show here,
if you look at these objects through a telescope or through binoculars,
you won't see in colour.
Now, your eyes are very, very efficient at detecting light,
but when it gets to very low light levels, they're not very good at detecting colour.
It's more important to be able to see that there's a tiger that's going to jump out
and bite your head off than it is to see the colour of its stripes.
So, when you're at very low light levels, your eyes are much more sensitive
at detecting light or absence and detecting movement,
than they are at picking up colour.
But a camera, on the other hand,
your eye takes may be a hundred images per second, effectively,
so you see the movie of life unfold in front of you,
a camera can keep its lens open for minutes or hours,
and so can collect all the light it wants,
and that's why you can get the colours in such vivid detail.
The reason I'm showing this is,
this is one of the few objects in the sky where you really can pick up colour.
And if you get someone to show you Albireo
through a pair of simple binoculars, a cheap pair of binoculars will show this,
you'll see the two stars, one golden, one generally bluish,
sometimes greenish, depending on your eyesight,
shining there perfectly in the darkness of space,
so that's a lovely thing to pick up, and that is, once again,
the head of a swan, there, see, find Deneb, Vega,
and this star down here called Altair,
and down in the middle you've got Albireo, kind of on its own,
really well worth a look.
Moving further south in the sky – now, this is the kind of thing
that you have to be very lucky to see a sky like this in the UK,
because we have lots of light pollution,
much worse than this, down on the southern horizon –
this is the kind of sky you'll be presented with just after sunset.
This group of stars here is Scorpius, the scorpion.
That's now pretty much setting just as it's getting properly dark.
Very low on the southern horizon.
That, again, to give you an idea of how bright things are, is Jupiter.
This was taken about a year and a half ago, I think,
Jupiter's now over here somewhere.
But you see this area down here,
on the previous slide here you've got a lot of milkiness there,
that's the Milky Way, which is our galaxy.
And when you're down onto Scorpius and Sagittarius,
you're looking towards the centre of this island universe we call home.
And because of that you see it bulging out towards the middle.
Our galaxy is like two fried eggs slapped back-to-back.
The yolk is the middle of the galaxy and we're somewhere out in the white,
out in the suburbs.
And when you see the Milky Way in full glory from a properly dark site,
you do kind of get the feel of the bulge at the centre.
But this part of the sky,
because we're looking right into the midst of our galaxy,
you get lots of really beautiful objects.
I just thought I'd show you some of the things you get.
Again, remember, you wouldn't see this much colour with the naked eye.
This is something called the Trifid Nebula,
which you can see through the telescope here when it's clear,
can see with the naked eye if you go somewhere really dark,
it's kind of a tiny little smudge on the sky,
but you can see this through a lens structure in the gaseous cloud,
if you look through a cheap pair of binoculars and you're somewhere
where you've got a reasonably good sky and you can find it.
The colours come out when you do the photography,
and they're telling you different things about the stars
that are around this gas, effectively.
The blue light, the blue nebulastar here,
is just gas and dust floating around being illuminated
by all these bright blue stars here,
it's called a 'reflection nebula,' and it's merely just reflecting the light.
The red cloud here is a big cloud of hydrogen.
In the middle of that cloud of hydrogen,
you've got a lot of baby stars that have only just been born,
and they're heating up and exciting the hydrogen and making it glow.
And when you get hydrogen heated up and glowing like that,
generally you get this red light.
It's a very specific type of light called Hydrogen Alpha,
which is one of the lines that you get from hydrogen
if you know anything about how atoms emit light.
But the end result is that lots of baby stars in the middle,
heating up the gas, exciting it, making it glow,
you get lovely red emission nebula.
This is pretty good.
This gives you the idea of the area around the Trifid.
The Trifid's down here now, we've zoomed out a bit.
And you've also got these other great emission nebulae.
These are all places where – they're stellar nurseries.
Young stars that have just been recently born
and they're still cuddled together for warmth,
and they're heating up,
exciting the gas from which they're formed as it blows away,
then you get these lovely nebulae, you've got the Lagoon Nebula here.
There's quite a famous object a bit further to the left, going up the galaxy,
this is called the Eagle Nebula.
You can get photos to this,
you can image it quite easily with telescopes like we've got here,
but this is with a professional observatory,
but these features here that you see might look familiar to you.
Now, I've not put the image in here, but if you look on the Internet,
search for Astronomy Picture of the Day, somewhere like that,
and look for the Pillars of Creation,
you may remember the big news story a few years ago,
wonderful images from Hubble zooming in here,
and the thinking is that there are new stars being born at the end here,
so, you've got a very dense area of gas and dust
but light from this fresh cluster that's being formed is blowing material away,
and when you zoom in on her you can actually see the area
where stars are forming now.
Looking at the other side of the sky, this is the Great Bear.
It's another one of those constellations
that really does look like what it's meant to,
once you figure out how to look at it.
I think everybody's familiar with the Plough,
which is the basis of a bright part of the Great Bear.
You have the tail and the body.
What you don’t normally see, unless you know where to look in Milton Keynes,
because there's bad light pollution,
you've got a string of stars coming down here to these two,
a leg, you have another leg coming down here to the foot,
and then you've got kind of a head out here somewhere.
Again, it's a fairly good constellation that looks like what it's meant to,
but it's a very good way to find your way around the sky.
If you take these two stars and follow them up, just off this picture,
somewhere up there,
you'll find the Pole Star, Polaris.
If you can see that and find it, you know you're looking north.
And Ursa Major rotates around over the course of the night,
but these always point to that star.
But there's a lot of pretty objects in this part of the sky, as well,
I thought I'd flag up a couple of them.
This star here, any night you go out on a clear night,
have a look at that, just with your ...
try and work out what you see, because I think you can see there,
it doesn't look quite the same as all the other stars.
That's another double star,
but it's a double star where the two components are so widely spaced,
you can separate them with your own ...
The two stars are actually about one light year apart,
light would take one year to travel from one to the other,
but, if you zoom in on it with a big telescope, you see that the Loma one,
the slightly brighter one, is itself double.
And if you take measurements of that cell with a really big telescope,
so it can measure how quickly the stars are moving in space,
you find out that each of those stars is double again.
So, that's kind of a five star system.
But we've got other pretty things up there.
Underneath the Plough, buried away,
you've got this galaxy here.
This is a photo, again, that I took out in Majorca,
using the ten inch telescopes on the OU course SXR208,
'Observing the Universe,' you see a spiral galaxy.
This is probably what our galaxy would look like if you were way, way,
way above looking down on it,
have spiral arms and a big bulge in the middle, spiral arms curling out.
This is a satellite galaxy, a galaxy that's interacting with the big spiral.
If you get, again, slightly more expensive equipment,
it looks like that.
Now, you'll remember me telling you about the dust and the gas,
and we see the pink gas where stars are forming, have these emission nebulae.
Look at this, everywhere you see, you're seeing nebulae,
like the Orion nebula, like the Lagoon nebula,
you're picking them up in this distant galaxy.
See, we've got mainly blue stars in the outside and yellower stars in the middle,
that's because the brightest stars you get, the hottest stars, are generally blue,
but they don’t live very long.
So, in the spiral arms, you've got all these new stars being born,
and you're seeing the very brightest and very biggest and very hottest of them,
giving it this blue light, because they're big, blue, hot stars.
But hot stars have very short lifetimes for stars, 10 million years.
I wouldn't mind living 10 million years, but for a star, it's very, very short.
In the middle, you've got much lower extra star formation,
so you have very few bright blue stars.
The blue stars have died, the next stars down,
the ones who aren't quite as bright, live a bit longer, give it a yellow tint,
because they're stars like our sun.
So, in this kind of area,
you've got lots of stars a similar colour to our sun and redder,
not so many of the big bright blue stars,
so that's why you get the colour difference.
And all of these dark features are clouds of dust that aren't hot enough
to blow and so are blocking out the light from what's behind,
and they're probably going to, at some point in the future,
have star formation going on there.
This is something else you can see up in Ursa Major.
This – you remember the ring we showed a little bit earlier,
this is another planetary nebula,
another star like our sun that's puffed off its outer layers,
blown a gentle smoke ring, but it looks a bit different.
You've got two eyes, a little beak, it looks like an owl, allegedly.
Things in astronomy that are named after things,
really you need a good imagination to be able to tell,
and that's another one of these little galaxies.
A better pair of galaxies up in Ursa Major,
these two, which are M81 and M82, we're back to Messier's list of objects,
things that he kept confusing with comets and kept annoying him.
M81 is a fairly big spiral galaxy a bit like ours.
M82 is weird, really is very, very odd.
It's what's known as a 'starburst galaxy,'
and that's an object where lots of new stars are being born
at an incredibly accelerated rate,
something's disturbed, it's smashed all the gas and dust together
and it's effectively exploding into life.
And you can see the spiral looks fairly well-ordered, fairly regular,
that's got material spraying all over the place,
and when you see this through a telescope with a very small telescope,
you can fit them both in the same field of view
and they're really a startling contrast.
And they're also so far north you can see them at any time of year,
so, any time you go down to one of the local astronomical society
and they've got a clear night, somebody's got a telescope,
they can show you these.
Constellations, these are the kind of things I would have been pointing out
with a laser pen if it were clear tonight,
but, to give you an idea of a few of the constellations you can see
in the evening at the minute,
Cygnus is here, so you've got the wings swept back,
Deneb at the tail and the long neck, that's Vega and Lyra, which is a harp,
kind of looks like a harp.
This, four stars in a diamond and a little one just off to the side,
is Delphinus the Dolphin,
you can just imagine it kind of leaping out of the water.
Then it gets a bit less clear.
This is Cepheus, who's the King,
and I guess because it looks vaguely like a bloke with a pointy hat or something.
And also we have this long, winding constellation here is Draco the Dragon,
I guess that's the head and it's a long, worm-like creature slithering along.
This is the Little Bear, Ursa Minor, that's the Pole Star,
to give you the reference.
Ursa Major will be down here with those pointing up to the Pole,
pointed stars there.
You see the trees are blurred,
when the Earth rotates – this is a very long exposure,
looking at the length of the trees, this is probably an hour's long exposure,
and the camera has been driven to track the stars,
so you know if you go out during the daytime and then go out an hour later,
the sun's moved a significant distance in the sky,
if you do it at night, the stars have moved that distance,
and if you didn't have something following them,
you'd have long spirally trails going around the Pole,
but because they track the stars to get them as points,
you've got tree trails, instead.
Up here, remember, this is overhead, this is horizon, this is Hercules,
kind of great figure of myth and legend.
You've got the body here, the arms going off up here,
and the legs dangling down here.
If you zoom in here, you can just about see a little fuzzy blob there.
There's a thing called a globular cluster there,
which I think I possibly have as the next slide, actually,
so I can tell you about that in a moment.
You have – this star here is Corona Borealis or the Northern Crown,
got a lot of constellations up there and if it's clear then you can,
with a little bit of practise,
go from a plot like this you find on the Internet to find your way around the sky.
Something we have down to the south,
arriving probably south-east and rising during the evening.
This big box here is the square of Pegasus, Pegasus is a flying horse.
You've got the body, the legs, the head, and then, attached to the Flying Horse,
you've got the constellation, Andromeda,
who was famously a maiden who was chained to a rock –
they used to do things like that back in the olden days,
they didn't have TVs to keep them entertained, I guess.
This is illustrate that another thing you could see tonight
and another thing that I could teach you to go out and find anytime you want
so long as you can find this big square, the Square of Pegasus.
That top left star is actually in Andromeda, it's slightly weird,
but if you find that star and go, bright star to the left,
bright star to the left, and then go up one star and up another star,
you come to the thing with an arrow there,
which you see easily with the naked eye.
See Andromeda galaxy, which is a bigger version of our galaxy,
it's about one and a half times the size of our galaxy.
To give you an idea of how big that actually is, our galaxy,
from one side to the other,
is about 100,000 light years across
and probably contains 100,000,000,000 stars, roughly.
In the time I've been talking to you,
it might have a few more or a few less than it started with,
but you get the idea.
That galaxy's about one and a half times the size,
and the light from that has taken over 2 million years to reach us,
and yet you can see it with the unaided eye on a reasonably clear night.
This is a slightly different picture of the area.
You've got the top left star in the square here,
top right star in the square,
so, like I say, you go left one, left two, up one, up two, and this is the galaxy,
a big fuzzy area.
For those who know the sky, different things,
so 'W' here is Cassiopeia, Lady in the Chair,
and we've got the constellation Perseus just out of shot here.
So, another way to get to the Andromeda galaxy is find the 'W'
and follow this little arrow pointing down to it, fairly easy to find.
If you actually see that in the night sky,
you don’t quite get the grasp of how big it is, how special it is.
To put it in comparison,
you never get the moon going as near to it as this,
but if you put them side-by-side in the sky, this is what you'd see.
The Andromeda Galaxy's truly immense in the sky.
You can fit the Moon about five times across from one side to the other.
It means it's 2 or 3 degrees of the sky in size.
If you ever go to somewhere really, really dark,
a long way from street lights, really, you can't miss it, spectacular.
And it's got its own little satellite galaxies, the dust lanes again,
the yellow centre, the blue outer regions,
a fairly typical spiral galaxy.
Just below the Andromeda galaxy, about 10 degrees further south in the sky,
you've got a face-on version.
Not the Andromeda galaxy this time, this is M33,
which is another nearby galaxy,
but where you see the Andromeda galaxy edge-on,
kind of tilted at about that angle, this one's properly face-on.
This one's smaller than our galaxy
but you can still, again, see star formation areas, that one especially,
these big glowing pink nebulae.
And this is something that looks pretty good through small telescopes,
but both this and the Andromeda galaxy,
if you have a really big powerful telescope and look at them,
you don’t see much, because you zoom in way too much,
so you just see tiny little area here, doesn't look that exciting.
So, the point there is that some of the objects that are up there in the night sky
at the moment aren't better seen through telescopes at all,
but are better seen with binoculars or even with the naked eye,
and the constellations are a good example of this.
Some of the planetary nebula – this is called the Dumbbell,
this is just behind the Square of Pegasus, M27, and this is something,
again, that you can see at your local astronomy society,
if somebody's got a telescope, a pair of binoculars,
it's fairly easy to find, and it's another star like a sun,
that's just puffed off its outer layers in a gentle little smoke ring.
Finally, there's something you can see pretty much any time of the year.
We're back to the unstable objects and my kind of thing again.
These are shooting stars or meteors.
Everyone of these little streaks was an object about the size of a grain of sand,
maybe a little bit smaller, maybe a little bit bigger,
that hit our atmosphere at 10, 20, 30 kilometres per second,
that's quite enough to get to London in two or three seconds from here.
Because they're travelling so quickly,
they hit the atmosphere and they burn up really, really brightly,
and we see them as meteors.
Now, on any clear night, at any time of the year,
if you stand out there and watch and let yourself get dark-adapted,
you'll probably see about five per hour,
once you've got your eyes used to the darkness,
but, at certain times of the year, we cross the path of a comet,
the orbit of a comet, or the path of an asteroid,
where the debris that they've left behind them as they've gone round the sun,
is moving around the sun, and as we run into it,
you get that debris burning up in the sky, and you get this kind of effect.
You get meteors radiating out from the point on the sky.
And that's just perspective.
If you stood on a bridge over a road,
you see the street converging towards the horizon,
spreading out as it comes nearer to you, it's exactly the same thing with this.
And you can see meteor showers around about through the year,
some better than others.
We've just had the maximum of a meteor shower called the Orionids,
which typically gives you rate of 20 or 25 metres per hour,
and if you went out tonight,
you'd probably see the tail end of that later on in the evening,
that may be 10 an hour,
on top of which you can also see the Taurid meteor shower,
the Orionids come from just above the constellation Orion here,
the Taurids come from around here, you'd see another ten an hour from that.
But, if you go out on 13th December, which is pretty much full moon,
unfortunately,
that's also the maximum of a meteor shower called the Geminids,
which come from Gemini, which is just off to the left of Orion and up a bit.
And they can give you, in good years, a hundred per hour.
So, with the full moon,
with the fact that the lights in Milton Keynes aren't that good,
you might see 30 per hour, but it's still pretty good.
And the beauty of that meteor shower is, you can see it in the early evening,
so, if you've got work or school, it doesn't matter,
you don’t have to stay up all that late,
nine o'clock in the evening when it's dark,
you can walk out and watch meteors for half an hour, if it's clear.
Unfortunately, it isn't clear, so, I'm going to finish up there,
and give you the option of working out what you want to do next.