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Welcome to our first night sky lab of the semester.
In these labs we'll be learning how the night sky
looks in different seasons of the year, we will see that it
is slightly different.
We will be learning the constellations, a little bit
about the constellations.
Some of the stars in those constellations, their names,
and some of their properties.
And also some of the other objects that you might need
binoculars or a telescope to see, but that are relevant to
what we're learning in class.
In this first video, we're going to look at
the northern sky.
We'll look at the northern sky in every single season,
because we will find the same constellations there.
And that can help us orient, both learn our constellations,
and find what direction is north if we're outside on a
random night and our compass or GPS is not working.
So what I want you to do, if not right now, later, is open
up Stellarium on your computer.
It defaults to the current date and time.
So we're going to make a few changes to make it easier for
us to do the lab.
And these will use some tools that you already learned in
your introduction to Stellarium.
And some that we haven't used yet, that add a little more
complexity to it.
The first thing we need to do, is we need to stop the
simulation, or stop time.
If you remember, we do that in the lower menu by hitting the
Pause button.
And now we want to change the date and the time, so that
we're all at the same date and time.
So let's do February 1--
we can just go forward a few days here--
at 9:30 in the evening.
Nine is 21--
this is 24-hour time.
Minutes 30, and seconds 0.
So this, as you can see by the red S, that
we're facing south.
A few more things to do, and if you look carefully, you can
see that on the horizon, we have some trees.
And trees and buildings, while they're there in real life, in
real life you have the opportunity to sort of go gaze
around them if they're blocking your view.
And we don't have that here.
So let's change the horizon.
We do that by coming over to our left hand menu.
We can click on the Sky and Viewing Options window.
And then if we go to Landscape, just
change it to the Ocean.
And this will change the view to an ocean horizon, which
will be completely flat.
While still in this same view, go over to Sky, and the sky
automatically adds light pollution.
So let's reduce the light pollution slightly--
3 which is the default, is a little too much for what we
want to do.
And finally, let's turn off the planets.
So come over here to Show Planets, and uncheck it.
So this way, any bright planets that are in the sky
won't appear and mess up our view of the constellations.
Because planets change where they are in the sky over time.
Just because the planet is there tonight doesn't mean it
will be there some other night.
So now we can cross this out.
The last thing we want to do is, if you look down here at
the bottom of your screen, you see this FOV 60 degrees.
That stands for field of view.
And 60 degrees is sort of a default.
It's more or less what your eyes can see, your eyes can
see a little more than that.
So let's zoom out just a little bit.
Now to zoom out, you can either use the Page Up and
Page Down buttons, if you have those on your keyboard.
Or if you're on a Mac, and my Mac doesn't have the Page Up
and Page Down buttons, if you're on a Mac you can use
the Command key.
That's the funny little four-pointed symbol, and the
Up and Down button.
Up zooms in, and Down zooms out.
And let's zoom out so our field of view is something
close to 90 degrees.
Now the unfortunate thing is that you can't enter an exact
field of view here in Stellarium, so we're always
sort of guessing.
So as long as you get close.
If you're somewhere between 80 and 100,
that'll be good enough.
And finally, let's swing around so that
we are looking north.
So we can use the left or the right arrows, swing around
until the N is in the center.
And now we're looking north.
In the north, there are several constellations, but
there are three that you may have heard of, three that are
fairly easy to see.
And so those are the three that we will learn.
And these are the Big Dipper, which its official name, and
the name I want you to learn, is Ursa Major.
Which means "The Large Bear".
There's the Little Dipper.
Its official name is Ursa Minor, which
means "The Little Bear".
And Cassiopeia, which is the queen if you've seen the
movie, Clash of the Titans.
The reason to learn these is that the tail of the little
bear, the tail of Ursa Minor, contains the star Polaris.
Polaris is the North Star, and contrary to popular belief, it
is not the brightest star in the sky.
Let me point upwards a little bit here, and you see that the
star Capella, up here, is far brighter than anything else.
But Polaris is actually this star right there.
So Polaris is a moderately bright star, it is usually
visible, but it's not the brightest star in the sky.
So if you're lost and you try to find north by picking the
brightest thing you can see, you're going to
pick the wrong thing.
So let's start with Ursa Major.
The Big Dipper is one of the easiest things to see
in the night sky.
It's very recognizable once you've found it.
It is fairly large, and it will look larger out in the
real sky than it does on your screen here.
So let me begin by putting up the constellation line.
The Big Dipper is over here.
This is the dipper part of it, and what you see is that the
dipper is part of a larger constellation.
The lines outline the rest of Ursa Major, the big bear.
And to give you an idea, here is the head of the bear,
here's its front paws, its body--
and so you see that the bowl of the dipper
is part of its body--
its back paws, and a long tail.
Of course, we know bears don't have long tails, but these do.
We can bring up some artwork.
And this is just to help you see what each object is
supposed to be, to show you that indeed is a
bear with a long tail.
We'll turn the artwork back off.
And so you don't need to know all these fainter stars in
Ursa Major, but I do want you to know the
dipper portion of it.
So here's the bowl, and here's the handle.
Now these two stars at the end of the bowl are called the
pointer stars, because if you take this line between them
and go straight, you come to Polaris.
So if you can find the Big Dipper, and find those pointer
stars, you can get to Polaris, the North Star, which you see
is almost perfectly due north.
Polaris is part of Ursa Minor, the little bear, and the Ursa
Minor constellation is also the same thing
as the Little Dipper.
You see here's the little bear's tail, or
the dipper's handle.
And these stars in the dipper, other than Polaris, are pretty
faint and often hard to see.
And the bowl is right here.
This part of the bowl on the left is faint, but these two
stars at the end are moderately bright.
So often in a bright sky, such as in a city, you may only see
Polaris and the two stars at the end of the bowl of the
Little Dipper.
So again, the pointer stars are useful because you can
usually see the entire Big Dipper, and you can use them
to point out Polaris.
Again, let's look at the artwork, and you see we've got
a little bear to go along with our big bear.
The last constellation we want to look at here is Cassiopeia.
Cassiopeia is over here on the left, and it looks like a W.
Cassiopeia is a queen.
And you may be saying to yourself, well how is that
sort of sideways W a queen?
Again, we'll put up the artwork, and you see that it
sort of indicates her two shoulders, her
waist, and her leg.
She's sitting in a chair.
In some mythology she's chained to the chair as
punishment for her crimes.
So I always just look for a W. Some parts of the year it
looks like an M. Some parts of the year it looks
like a letter 3.
Right now it looks sort of like a curvy letter E.
There are some times of the year where you can see
Cassiopeia, but not the Big Dipper,
especially in the fall.
So if you can find this W, notice that the point, here in
the middle, points more or less in the
direction of Polaris.
It's pretty much the only bright star in the direction
of the point, until you get to Ursa Major.
So these are the three northern constellations that
you need to know.
Now we will find out that they are always present in the sky,
but they are in different positions depending on the
time of year.
In the fall, the Big Dipper is very low in the sky and often
very hard to see.
In the spring, the Big Dipper is high in the sky, and
Cassiopeia is low in the sky and often hard to see.
We'll see that as we go along over the year.
So this is the way that the northern sky
looks during the winter.
And I'd like you to be able to identify, from the dots
alone-- so if we get rid of the constellation lines--
I'd like you to be able to identify Ursa Major, Ursa
Minor, Cassiopeia, and Polaris.
So now you can complete the first couple pages of your lab
that deal with the northern sky, then proceed to the other
video where we can learn about the bright constellations
visible in the southern sky.