you think of exploring astronomy, you probably think of using
telescope to view the moon, planets or other objects in the
sky, and many great discoveries have been made since
the invention of the telescope. One of the first
astronomers to use a telescope to study the heavens was the
scientist, Galileo. His work led to the discovery of the
natture of planets. However, before the telescope,
the night sky with just the naked eye, and their observations
groundwork for the discoveries that would later be made with
many centuries before Galileo, people who studied the stars
that most of them seemed to move through the sky in a fixed
almost as though they had been painted on the inside of a
surrounding the earth. This pattern of stars appeared to
and set in the west every night. As the nights
throughout the year, te pattern would appear to gradually
shift, but it was always the same pattern.
few of the stars, however, seemed to slowly move around the
paths of their own. These stars were called "wanderering
stars." The ancient observers identified five such
named them Mercury, Venus, Mars, Juipter and Saturn.
far as everyone knew, they were just stars, like all the
that they just somehow managed to move around on their own and
sometimes be brighter than at other times.
when Galileo pointed one of his first telescopes at a couple
planets, he made some amazing discoveries. Venus was not
bright star - it was actually round and looked very much like
moon. In fact, over time it would actually go through
like the moon, which explained why it looked brighter at some
than at others. And when Galileo first looked at Jupiter, he
it was round as well. But even more amazing, Galileo saw
Jupiter had moons of its own circling the planet. These
stars were not stars at all. Galileo realized that he
actually seeing other worlds!
kept improving and many more discoveries have been made ever
since. Today, we have modern observatories on earth with
giant reflector telescopes, and space
telescopes such as Hubble orbiting the earth. Yet as
important as the discoveries
made by telescopes are, they never could had been made without
centuries of careful observations of the sky without
the activities that follow, you will learn how to observe and
some of the stars and constellation (or patterns of stars) in
sky using only your eyes, and you will also learn how to
locate them on
any given night from where you live. You
will also learn how to locate the planets and observe the
phases. You will do this by using a free computer
Stellarium, a planisphere, and a simple homemade instrument
may have already studied some of what is presented here
school work, but if you have never actually gone outside and
things you have studied, you have missed much of what
astronomy is all
about, but if you are willing
to take the time to work through these activities, you can
competent observer of the skies without a telescope!
activities assume that you don't have someone with you that
you locate the stars. If you do have someone who can
help you, so much the better. Also, if you work together
group of friends, this will be a lot more fun.
of the outdoor activities cannot be done where there is a lot
artificial light. If you live in the city, much of what
want to see will be made invisible by bright
outdoor lights. However,
using Stellarium, you can at least see what you are missing,
and you can see it just as it would appear in the night sky.
because The Science Notebook staff is located in the Northern
Hemisphere, some of the outdoor activities are based on
constellations visible only in the
Northern Hemisphere, but the same principles can be
to the Southern Hemisphere as well.
So let's get started!
you learn your way around the night sky, you have to have some
knowing where to look for what you want to see. You also
know how to find the point in the sky where you want to
Star charts and star finders can help you see what the sky
you looks like at any given time, and they are either
or free. (We'll tell you how to get the free stuff later
on.) But these won't do you much good until you learn to
recognize a few stars, and the patterns of stars you see in
The best way to do this is to have someone to show
you how to find these things in the night sky, but the next
is to use a good computer program that shows you what is in
the sky and
where to find it. So, to begin your study of the night
should download a copy of an excellent and free program called
Stellarium will let you view the
on your computer as it appears outside no matter where you
This can be very useful if you live in a city where bright
you from getting a good look at the night sky, or if the weather
happens to be bad. In addition, Stellarium will let you
sky at some past or future time, or from a completely different
location, and it will allow you to slow down or speed up
time. It will also let you turn on labels that will help
you identify stars, planets, constellations, and other
objects. Stellarium will also show you the patterns of the
various constellations, and it even has a function that will
zoom in on
the moon, planets and other objects to view them close
Interested? Well, to get a copy of Stellarium, go to the
Stellarium website at:
there, you will find a link that will let you download the
Linux, Mac or Windows. You should also download the PDF
User's Guide. Once you have downloaded both the install
the User's Guide, install Stellarium on your computer.
If you are not sure how to download and install programs on
your computer, get someone
to help you! You need to follow the instructions for
operating system in the User's Guide. Unfortunately, we
you step by step instructions here because they are different
system, and because the program is constantly being updated.
the program is installed, you'll need to configure it for your
location. You'll also need to set the date and time and
whether you live in an area that uses Daylight Savings
In addition, you'll need to pick a city near where you
live, or else enter your
latitude and longitude and make it the default location where
Stellarium will "go to" when it is started. For the
that follow, a nearby city will be close enough, but if you are
near one of the listed cities, you can enter your latitude and
longitude. You can locate your latitude and longitude
get it from a GPS unit.
There are several other settings
that you can change once you become familiar with the program,
but for now, all you need to do is get your
default location and time right.
the program is properly
installed, you should be able to see what constellations and
objects are visible outside on the Stellarium dispay on your
screen. If it is day, you will see the daytime sky.
night, you will see the stars.
There is so much you can do with
Stellarium, but for right now, let's just look at some of the
is probably better (but not absolutely necessary) to do these
activities after dark so that Stellarium will start with the
Stellarium installed and configured for your location; the
Stellarium User's Guide.
Stellarium. If it is day time, press [CTRL] and [=]
together. For each time you press them, time will advance
hour. Press until the time is night and you can see the
Now, hold the left mouse button down and drag your mouse to look
around the sky. Take some time to explore.
if you have not found them already, you should locate the
invisible toolbars at the left and bottom of the screen.
move your mouse down near the bottom left of the screen, the
toolbar will appear, and if you move your mouse to the lower
side, the left toolbar should become visible.
Let's start with the left toolbar and explore a bit.
you move your mouse to the lower left edge of the screen, the
toolbar will become visible with six icon buttons. From
bottom, they are:
- Date and Time
- Sky and Viewing Options
you mouse over each button, it will identify itself.
any button will open a new window that will allow you to change
settings. Let's see what they do...
on the Location button to open the Location window. This
will allow you to set your default location (which you should
already done), either by entering your latitude and longitude or
selecting a nearby city. You can also select another
view by (1) entering another latitude and longitude, (2)
another contry or city, or (3) clicking on the map. Try
each of these methods to move around the world to other
locations. You can always return to your default location.
you get stuck, the next time you reopen the program, you will be
back to your default location.
Date and Time
Date and Time window will let you move ahead or backward to any
or time. As you change the date or time, you can see the
in the night sky on the screen. Try it. (Don't worry
resetting the time before you close the program. The next
you open the program, it will reset to today's date and time.
Sky and Viewing Options
Sky and Viewing Options window allows you to adjust a number of
different viewing options including changing the
you want to change the default landscape, feel free.
you probably shouldn't change any settings here until you get to
the program a little better.
Search window allows you to look for any object. Type in
and see what happens. (If you click on any object in
including some below the horizon that are not visible, it will
surrounded and identified in the upper left hand corner of the
screen. To make this information go away, just right click
Configuration window has a lot of settings that you don't need
about until you become more familiar with Stellarium.
described in the User's Guide.
Help window has a lot of really useful information. It
keyboard shortcuts that are very useful. These are also listed
User's Guide, and you might want to print them out for handy
but you can see them at any time just by clicking the Help icon.
let's take a look at the bottom tool bar. When you move
mouse down to the bottom of the screen near the left hand side,
bottom toolbar appears with nineteen buttons that turn various
on or off, or toggle between two different functions.
these from left to right.
first three buttons show or hide the imaginary lines
constellations, labels for the constellations, and some neat
that shows what each constellation is named for. Try
one on and off. You can have more than one on at the same
Move around a bit to explore the sky with each of these buttons
buttons will turn two different imaginary line grids on or
grids are used to locate objects in the sky, and you can display
both at the same time. In the explorations on this site,
be using the azimuthal grid, although we won't need to turn it
on right now.
But go ahead and try each of them. What happens to
these grids when you move around around the night sky?
button will show or hide the landscape. Hiding the
allow you to see objects that are actually below the
button will turn the cardinal directions - north, south, east or
on or off. These directions will help you get your
you start studying the sky.
button simulates the haze near the horizon. You can turn
so you can see the stars near the horizon much better, but in
cases, showing the haze of the atmosphere near the horizon is
more realistic. Even during periods
of fair weather, it is often hazy near the horizon.
Try turning this function on or off to see what it does.
button will label the location of nebulas when turned on.
are huge clouds of dust and gases. They are often not
without a telescope, and the ones that are will appear as
Click this button on and look for the
labels. What you see displayed will depend on your local
location, as well as the time of year.
button will label the planets. Toggle it on and move
sky to see whether you can find any planet in the sky.
(Hint: More planets are usually seen around sunset or
than late at night.)
button is used for one of Stellarium's advanced functions -
telescope control. Click this one on and off to see the
but for our work, we're not going to need it, so we'll leave it
you click on any star or other object, it will be identified and
labeled. If you then click on this button, that object
centered in the screen. Try it with several stars.
mentioned above, you can remove the label by right clicking.
you click on this icon, it will turn on a dull red background on
ground. This is useful if you have Stellarium on a laptop
take outside with you. Try it.
This toggles between a full screen view and a window.
Again, try it.
Clicking the big red "X" will close Stellarium. Try it now
if you want, or just try it once you are ready to quit.
Decrease Time Speed
Normal Time Rate
Set Time to Now
Increase Time Speed
four buttons will really let you have fun with Stellarium.
time you hit the Decrease Time Speed button, time begins to run
backwards! Each time you hit the Increase Time Speed, time
up ten times faster than before. Normal Time Rate will
movement of the sky at normal time, whatever that time is when
click the button. Clicking Set Time to Now will take you
the current date and time, just in case you have gotten ahead of
yourself. Take some time to play with these buttons while
watch the sky.
Here are some things to try on your own or with the help of
- Go ahead or backwards in time using the time setting. or the
bottom toolbar buttons
- Speed up time so that you can see the stars move through the
night sky in their fixed pattern.
one of the planets in the sky by clicking on it. Then,
zoom function (mouse scroll wheel or page up/page down to zoom
to it. (Press "/" if you are in a real hurry to get
there, and "\"
to return to where you started from.
- Do the same for the moon.
- Go outside and see whether the pattern you see in Stellarium
looks like what you see on your screen in a particular
Now that you have seen some of what Stellarium can do, take some
to play with Stellarium. Be sure to keep the User's Guide
and feel free to explore with Stellarium. You really can't
Observing How Stars Move In The
OK, playtime's over!
not really, but your first step in learning the night sky is
familiar with how stars move through the sky. In this
you will use Stellarium to see how the stars move over time,
observe the same thing outside.
computer with Stellarium installed and set up for your location,
clear dark night, paper and pencil, flashlight.
Stellarium. Make the following adjustments:
- Make sure the "Cardinal Points" button is enabled.
function is turned on, the four major compass directions will
displayed (N, S, E, W).
- Make sure that "Azimuth" button is enabled and that the
"Equitorial" button is disabled.
- If you are doing this during the day, press the [CTRL] plus
together to advance time until sunset one hour at the
press of this combination advances time by one solar hour.
your mouse to drag the horizon until you are looking north if
in the Northern Hemisphere and south if you are in the
When you are ready, face east
and watch the star
pattern and advance time one hour at a time through the
What do you notice about the pattern? Are there any
don't fit the pattern? If so, click on them to see what
Use the [CTRL] plus [-] key combination to return to around
sunset. Now increase time by pressing the icon (see above)
[L] key a couple of times. Watch what happens. Press
"Set Time to Now" icon on the lower keyboard to get everything
Repeat the above while looking north, west and south. and note
what you see each time
Now lets see this outside.
a dark clear night, preferably when the moon is not out, pick a
location outside, to the east if possible, that is easy to
remember and where you have a good view of the stars near the
horizon. (We'll do much more with directions later, but
in the general area where the sun comes up. OK, if you
knew that, sorry!) From that spot, choose a landmark that
to see such as a tower, power pole, or tall tree. You want
able to return to that same spot and face that same direction
a piece of paper. make a note of where you are standing and
direction you are looking by the landmark you have chosen.
out a shape within the pattern near the horizon that is made of
stars and and sketch it by making dots on the paper.
your landmark in the sketch. This will make it much easier
any movement in the pattern. Work carefully and study this
until you are certain you can remember the pattern.
that same spot and look in the same direction after one hour,
after two hours. Compare the position of the stars with
they were when you started. What do you see? Can you
this same pattern on Stellarium? Does the pattern appear
same place in the sky on Stellarium as it did when you observed
What You Saw: When
toward the north or south while using Stellarium, depending on
which hemisphere you live in, you should have observed that the
pattern of stars seemed to move in a semicircle, and moving from
to west. In the Northern Hemisphere, these stars seem to
around the star Polaris, also known as the "North Star."
Southern Hemisphere, there is no bright star that the rest
rotate around. In other words, there is no visible "South
Star," but the
stars do seem to rotate around an invisible point in the south.
should have noticed that the entire sky appeared to rotate as a
pattern of stars that does not change. The reason they all
appeared to move, however, was that the earth is actually
its axis once every twenty four hours, so when the sun goes down
the stars become visible, it looks like they are slowly spinning
circle above either the north or south pole, depending on where
are. As the night passes, some stars appear to rise over
eastern horizon as others appear to set in the west, just as the
and moon do. However, even though all the stars appear to move
a fixed pattern, in reality, it is not the sky spinning, but the
spinning underneath the sky.
you made your first trip
outside to observe the stars, what you saw should have been very
similar to what you saw using Stellarium. However, the
might have appeared slightly different due to your
you were near bright lights, many of the fainter stars werel
not visible. Also, it is not possible to represent
on a flat
surface such as your computer screen without some
However, once you get used to matching what you see outside to
Stellarium, it will become much easier to find your way around
If the sky outside did not look similar, you should
go back to Stellarium and verify that your date and location are
correct for the time you are observing and try again.
Going Further: You
change your location in Stellarium and see how this pattern
different locations. For example, if you were at either of
poles, the stars would seem to trace this pattern in a circle
center directly above your head because you would be standing on
end of the earth's axis. You can actually see this if you
your location to near one of the poles by clicking on the
Also try running through several days of time
around the first day of each season - the 20th of March, June,
September and December should be close enough. Depending
pole you choose. What do you notice about the lenghts of
night at each of these times of the year? Do you know why?
change your location to the opposite pole. Do you see the
star pattern? You may recognize a small part of the star
on the horizon, but otherwise you should see mostly a different
pattern. The reason for this is that the earth itself
view of most stars visible in the opposite hemisphere.
all the stars seem to be in a fixed pattern, in reality, all
are moving, and in different directions. However, it would
take hundreds of
years to notice this change with just our eyes. That's
all the stars we see are very far away. The absolute
to us is almost thirty trillion miles away, and most are many
farther away than that. (A trillion is a 1 followed by
zeros!) Even if a star moves several million miles a
would take many years for it to move enough so that we could
change in the sky on earth. Therefore, the pattern we
changing, but it is changing so very slowly that we would not
any change in our lifetime.
first astronomers spent many
nights watching the movement of the stars, and they noticed a
things about this pattern that would later prove to be very
to our understanding of astronomy. First, while the
changed, the pattern would appear to rise a little later each
night. This would later be an important clue in helping
understand that the earth orbits around the sun. Second,
noticed that there were a few star-like objects that seemed to
themselves over time and not with the pattern. These
"wanderers" that we now know to be planets. (See
Introduction above.) As people tried to explain
would ultimately also show that these were also bodies in
the sun. Finally, people also noticed that the moon
independently of the pattern as well. Explaining the
the moon through the night (and daytime) sky also helped to
understanding of astronomy.
NOTE: Many of the following
activities are based on observations from the Northern
Hemisphere. This is not meant to leave out half the
Rather, The Science
Notebook is writing based on the experience of its
staff. We could write about some of the stars in the
Hemisphere, but it would not be from experience, and so would
accurate. If you live in the Southern Hemisphere, you
to find someone to assist you.
Tools to Explore the
You can play with Stellarium for hours without
venturing outside to see
the real thing. However, the object of these activities
is to get
you to watch the sky itself. In order to do that, you
have got to
know how to find your way around on the ground. In these
exercises, we're going help you locate a good place to
We'll also see how to identify the different directions and
locate those directions on the ground outside, first using a
and later using the sky itself.
Location to Observe the Sky
you live in or near a city where there are lots of lights at
it may not be easy for you to do much stargazing, since night
can obscure all but the brightest stars. If this is your
situation, you may have to just use Stellarium for now, but be
stargaze the next time you find yourself in a good dark
if you are lucky enough to live in an area where there are not
many lights, the number of stars you can see will greatly
you should get ready to learn the night sky. If you do
such an area, the first thing you should do is identify a good
area for stargazing during the daytime. This area should
be easy to get to and have
the best view possible of the sky all around the horizon.
don't want a lot of tall trees or buildings around if
help it. Above all, pick a location where it is safe to
and be at night, and always let an adult know where you are
going before you leave. Never compromise your safety!
have picked what appears to be a good spot, visit it well after
to see how it looks at night. If the view of the sky is
ready to do some observing.
"Cardinal Points" with a Compass
Needed: A magnetic compass; a good place to
outside; flashlight, four rocks, plastic bottles; or some other
to mark the directions on the ground.
a look at the compass below. You'll notice that it is
the cardinal points - North, South, East and West. The one
have is probably also marked the same way. Also notice
that other points are also marked, such as North East (NE),
(SE) and so
on. We'll deal with those later.
compass may also be marked off in degrees from 0 to 360.
into more detail about those later as well, but for right now,
that North is 0 degrees, East is 90 degrees, South is 180
West is 270 degrees.
The compass has a magnetic needle inside
that lines up in a generally north and south direction. It
important to know which end is supposed to point north, and
supposed to point south. Most compasses will have a little
letter to let you know which end points north. (You can
much more about how and why a compass works on our Electricity
There is one slight problem with a
compass. Depending on where you live, the compass probably
doesn't point exactly north or south. That's because the
magnetic north and south poles are not exactly lined up with the
Earth's axis, so the compass is a little off in most
However, the compass will still give you a pretty good idea
the cardinal directions are, and that's enough for now.
fine tune things a bit later.
For right now, stand in the spot
where you expect to do your stargazing. From this spot,
the end of the compass needle that points north with the N on
compass and face in that direction. This direction is
north. Have a friend place one
of the plastic bottles or other markers in that direction from
you are standing. Keep the needle lined up with North on
the compass as you turn
to your right. You should now be facing east, and the E
in front of you. Place another marker in this
Keeping the compass needle lined up with the N, face right
You should now be looking south, and the south end of the needle
be pointed away from you. Place a third marker in this
direction. Finally, keeping the compass lined up with
right again, and you should see the W in front of you, which
are now facing west. Place a marker in this direction as
mark the spot where you are standing. If you have a
it would be a good idea to mark the four items you used as
markers N, S, E and
W. The markers should be placed so that they
easy to find with a flashlight at night from where you were
standing when the markers were placed.
you have done is marked the cardinal directions from exactly
were standing. This will help you quickly determine your
direction at night when looking at the sky. However, if
from that spot, you will have to identify the directions
After you get familiar with the compass, you should be able to
determine the four directions without any markers. Just
the N with the north end of the needle. When you face
is to your right, west is to your left, and south is directly
Because the Earth's magnetic poles are
not exactly in line with the geographic poles, your compass
off by several degrees. This is known as magnetic
and it has to be taken into account when knowing the right
critical. The direction the compass points is known as
north, while the actual north is known as true north. The
magnetic declination measures how many degrees east or west of
north the compass needle is pointing. You can find the magnetic
declination for your area by visiting:
example, if the magnetic declination at your location is
magnetic north lies 10 degrees west or counter-clockwise from
north. ("°" is the symbol for degrees.)
north is 10 degrees clockwise from the north point of the
If the magnetic declination is 10° E, magnetic
north is 10 degrees clockwise from true north, so true north
counterclockwise from the north point of the compass needle.
you were relying on the compass for exact directions, you would
make this correction, but if you live in the Northern
is a much easier way than having to depend on the compass!
before we get to it, we need to learn a little bit about
a couple of ways to zero in on stars and planets in the night
sky. The simplest way to go directly to a spot in the
sky is to
know the direction you need to look, or the azimuth, and from that
direction, how high you need to look, or the altitude. In this
activity, you will learn how to determine the direction or
in the next, you'll see how to determine the altitude.
really very easy.
Compass card illustration shown here:
compass card is a circle-shaped card that is either attached to
compass needle and swings or rotates with that needle, or is
compass needle, with the compass needle able to swing over
The compass card image shown above shows directions in two
ways. The traditional way of indicating direction measures
with reference to the four cardinal directions - north, south,
Locate the letter N for "North" at the top of the
circle. When the "N" or north on this card is actually
north, you can determine the direction of an object from where
by using one of thirty two points. Starting at North, the
point to the right is "North by East" (NbE), then "North North
(NNE), "North East by North" (NEbN), "North East" (NE) and so
many centuries, people who sailed the oceans used these points
determine their direction. Once a sailor learned the
it was fairly easy to use them, but they can be a little
The good news is you don't have to learn them!
that right above the N, there is also a zero and a degree symbol
(0º). If you move your finger around the circle, you
that the circle is divided into 360 equal parts. Each part
called a degree and is represented by the number and the symbol
degrees, "º". Also notice that every ten degrees is
marked by a
number showing the number of degrees from north.
degree scale, instead of having 32 possibly confusing reference
with different names, you now have 360 divisions you can
just a number.
Why 360º? Well, that is really a math
question, but for right now, you should know (if you don't
if we divide a circle like a pie, it is useful to divide it into
equal slices, and each of these slices measures one degree. (Not
good if you are hungry, but great for directions!) We also use
degree as a unit to measure the size of an angle, and we will do
in the next activity.
For right now, though, you just need to
know that you can indicate any azinuth or direction by so many
Again, look at the circle. You will see that north is
0º. east is
90º. south is 180º and west is 270º. For
the points in between,
you can indicate north by east as 11º, and so on. You
that you can identify directions much more accurately using 360
than the 32 compass points because you can accurately identify
directions between any of these points. In fact, by using
degrees, you can go from 32 possible directions to 360.
can line up north on this card with true north, the direction
location to any other location can be measured as so many
north. The direction of an object from your position is
A little later on, we'll actually line up a similar circle with
north and start locating some azimuths.
you with us so far? If you are, you are half way to
being able to
locate any object in the sky. Once you know the
need to face (the azimuth), you then need to know how high up
sky to look. In other words, you have to be able to find
altitude, and that requires us to look at degrees again.
the last exercise, you saw that a circle can be divided into 360
degrees. when two lines meet at a single point, they form
angle. Shown below are three kinds of angles.
angle can be measured in degrees using a protractor. You
probably seen one of these before, and they are very simple to
you have to do is to place the hole at the center of the
over the point at which the two lines meet, and place one line
the bottom edge. If the gap between the two lines along
is less that one half of the circular scale, the angle is an
angle and it is less than 90º. If the gap fills more
the angle is greater than 90º, and the angle is an obtuse
You have two scales so that you can measure the angle whether
opening is to the left or the right, but you have to know
whether it is
acute or obtuse in order to use the right scale.
protractor shown below is slightly different from the one above.
You will notice that instead of having to line the angle
the circle, this protractor allows you to line up one line of
with the bottom of the protactor. (If you don't know how
measure an angle with the type of protractor you have on hand,
means get someone to show you! A math teacher would be a
good place to start.)
The important thing to remember
is that to measure altitude, your angle will always be an acute
angle or less than 90º.
a look at the diagram below. The man is looking at a star
above the horizon. Just how far above the horizon?
imagine a flat line going to the edge of the horizon from the
eye, and another imaginary line going from his eye to the star,
an angle. If we have some way of measuring that angle, we
tell how far up from the horizon we have to look to find that
particular star. The measurement of that angle is called
altitude, and we can find it in a couple of different ways.
In this illustration, the man
is using a device called an "astrolabe" to measure the
first way is only approximate, but it will give a rough estimate
The man below is holding his arms outstretched with his hands
into fists. Straight to the horizon is 0º. If
the bottom of
the man's fist touches the horizon, an imaginary line running to
top of the fist is about 10º. When he places the fist
other hand on top of the first, an imaginary line to that fist
20º. He can do this all the way up to straight
overhead which is
90º and which should be about nine fists. By conting the
fists it takes to go from the horizon to the star or other point
sky, the altitude can be estimated.
Of course this is only
an estimate because nobody has the same size hands and arm
it should be fairly close for most people. Try it for
and see how close you are to stacking 9 fists when you reach
up or 90º.
There is a much more accurate way of doing this, and we'll see
it in the next activity.
you have most of what you need to know to locate any object in
if you are given its azimuth and altitude. What's
missing is some
sort of instrument to measure the azimuth and altitude of an
object. The ancient astronomers used a very simple
an astrolabe to locate objects in the sky, and we can
just have to make one, but fortunately, it is very easy to do!
Compass like the one shown below
(available as a larger image HERE
semi-circular scale like the one shown below (available as a
wooden base, upright stick; string; small weight such as a nut;
clean drinking straw; nails.
rose for azimith circle and protractor scale for altitude
Larger versions used for making the astrolabe and suitable for
printing are available by
clicking on the links in "Materials
Print out the compass rose and circular scale. Cut out the
compass rose and put it aside.
a nail from the underside of the exact center of the square
the way through the board. (If you have a drill to
holes, that might make things a little easier.) Take the
rose and push the point of the nail through the exact center,
the rose all the way down to the base. The exact
the board is not important so long as the compass rose
up the N with the middle of one side of the board and glue or
compass rose to the board. This will become the azimuth
Next, print out the semicircular scale on
heavy card stock and cut it out. If you don't have heavy
stock, glue the paper with the scale to a piece of cardboard and
dry. When the glue is dry, cut the scale and glue or tape
length of the drinking straw to the top edge and put it
This will become the altitude scale.
Next, use a small nail to
make a hole near the bottom of the straight stick about half way
through the stick. Remove the nail and find a piece of
coffee stirrer, or some other straight object that will fit
the hole. It should be about half the diameter of the
rose, and it will serve as a pointer. (The one in the
illustration used a length of coat hanger wire.) Remove it
take the same end of the stick that will have the pointer
attached. Carefully place the center of that end of the
the point of the nail coming from the base and tap the top of
to drive it into the nail. When driven in, it should be
the pointer back into the hole on the side. If the pointer
loose, you can use some glue to secure it better. Now
stick around so that the pointer sweeps through all 360 degrees
azimuth scale. The stick should be just loose enough to
Use a push pin or small nail to mount the altitude scale
at the top of the stick by punching it through the hole and the
the wood. It should be lined up in the same direction as
azimuth pointer. The altitude scale should be loose enough
that you can rock it up or down, but tight enough so that it
in place once you move it.
Finally, tie a small nut or other
weight to one end of a string, and tie the other end of the
the nail holding the circular scale as shown.
If your finished astrolabe looks
something like these pictures, you are ready to learn how to use
Needed: Astrolabe; magnetic compass.
Go outside and locate magnetic north with your compass.
your astrolabe on a flat level surface such as a table or
Next, line up north on the azimuth scale with magnetic
With the azimuth scale lined up with north, you can determine
direction (azimuth) of any object from you by turning the stick
and noting the direction of
Next, pick out several objects such trees, water
tower, power lines, a distant radio or cell tower, or roof
Now level the scale so that the straw is horizontal. It is
exactly horizontal when the sring with the weight hanging down
the zero mark on the altitude scale.
Turn your pointer to one of
the objects selected. What is its azimuth in
look through the end of the straw opposite the pointer and move
scale so that you see the top of the selected object through the
straw. Note where the string is on the scale. This
altitude of the top of the object in degrees.
Now determine the
azimuth and altitude for all of the objects you have
Have someone to check behind you to make sure you are doing it
you can put this aside for a bit and we'll get back to some
gazing. Once we learn how to find north in the night sky
a compass and observe a few constellations and stars, we'll
and learn how to really use this very useful instrument!
As you can probably see, to find your way around the
night sky, you
absolutely need to be able to find true north. You can
compass, but if you do, you may have to deal with magnetic
or else not be exact. However, there is a much easier
way if you
live in the Northern Hemisphere. By learning to locate
or the North Star, you will be able to instantly determine
where true north lies. Once you know where true north
is, you can
find any other point in the sky. These next two
show you how to find Polaris.
the constellation "Ursa Major" (or "The Big Dipper")
An ummarked view of Ursa Major
and Polaris from Stellarium.
Needed: Stellarium set for your location; paper
and pencil; an outdoor location facing north; magnetic compass.
Start Stellarium, and if it is daylight, advance time to about
sunset. Make sure the cardinal points are turned on and
mouse to drag the display around to the north, as indicated by
"N." Turn the constellation names and lines on.
at the horizon, begin looking for a constellation called "Ursa
Major." If you don't see the name immediately, look up by
the mouse to drag the sky straight down. Depending on your
location, and the time of year, Ursa Major could be partially
horizon or high in the sky at sunset. If you don't have a
view of Ursa Major, speed up time until you can see the sky
move. As soon as all of Ursa Major is clearly visible,
to normal time. Notice the shape formed by the imaginary
lines. Also notice the time.
NOTE: The illustrations here
were taken from a Stellarium screenshot taken in June
near Raleigh, North Carolina near midnight. The position
Major in your area will be different depending on the time of
time of day, and your location.
Make a sketch of the stars and lines and how they are positioned
in relation to the horizon.
The same view as above except
that the constellation Ursa Major is now marked.
A closer view of Ursa Major
with Ursa Minor to the right.
the "official name" for this constellation is Ursa Major, it is
sometimes called "The Big Dipper." This name comes from a
of seven stars within Ursa Major that take on the shape of a
dipper. The screenshot below shows Ursa Major with the
making up the dipper shape indicated by red dots. Two of
stars will become very important in the next activity.
You should also mark this dipper pattern on your drawing as
same view as above except that the stars of the "Big Dipper"
Ursa Major are now shown.
These seven stars are very easy to spot.
it's time to go outside and find the real Ursa Major!
the time showing on Stellarium when the sketch was made, go
face north. Using the sketch you made, can you see the
make up Ursa Major? How about the ones that make up the
Dipper? Remember how the dipper looks. This is very
important to finding Polaris!
The Big Dipper is usually very easy to spot once you
know where to
look, even when some of it is below the horizon. Once
able to identify the Big Dipper, Polaris is very easy to find
stars in the Big Dipper, and Polaris is the most useful star
to know in
the Northern Hemisphere. because it lies in the direction of
Stellarium set for your location; an outdoor location facing
Ursa Major for
the date and time you plan to observe on Stellarium as you did
last activity. Note the position of the stars in the Big
and sketch them as they appear above the horizon if you need
Pay particular attention to the two stars that are opposite of
dipper's "handle." In the screenshot below, they are
green dots. These two stars are used to locate Polaris,
are called "pointer stars."
two "pointer stars are colored green in this illustration and
located on the side of the dipper opposite the handle.
If you imagine a line
from these two stars going in the direction of the open part of
dipper, and about five times the distance between these two
next star you will see is Polaris. The common name for
is the "North Star."
pointer stars "point" in the direction away from the dipper's
Polaris is located about five times the distance between the
It is the only bright star in that general area.
The neat thing about Polaris is
direction of this star in the sky is always exactly north.
not exactly north, but it is so close for all practical
purposes that we can assume it to be exactly so.)
No matter where you are, if you can locate Polaris, you can tell
direction is north. Unlike the magnetic compass, it always
true north, and there is never any question of magnetic
declination. Its direction in the sky never changes.
Why is this?
position of Polaris as viwed from Earth is directly over the
north pole. The Earth's axis, or point around which the
rotates, runs from the geographic north pole to the geographic
pole. When the sky is viewed from anywhere within the
Hemisphere, the stars appear to rotate, while we
appear (to ourselves) to be standing still. What is
actually happening is that
the earth is rotating on its axis, and what we see as the stars
in circles around Polaris is actually the earth turning on its
may be wondering about now whether there is a "South
Unfortunately for our friends in the Southern Hemisphere, there
that is close, but it is too faint to be visible in many
locations. The name of the star is Sigma Octantis.
are several others that are fairly close as well, but not nearly
as close to
true south as Polaris is to true north.
Going Further: Go
back to Stellarium and find Polaris. Next, speed time up
you can see the stars move, and you will clearly see that they
do appear to trace circles around Polaris.
Also, to show that
Polaris is directly over the North Pole, set the time in
around December 20 of the current year, and use the map to pick
location at or near the North Pole by clicking as near to the
the map as possible. Loacate Polaris and speed time up
see the stars move. Two things you should notice are:
- Polaris will be almost directly overhead in the center of
the sky and
- Even if you speed up the time, it will stay dark all the
may remember from school that the north pole is in costant
winter and constant sunlight in the summer due to the fact that
Earth's axis is tilted. The same is true of the South
except that the seasons are reversed. (So what would you
you ventured down to the South Pole on Stellarium around
December 20? How about six
months later? Go ahead and try both.)
Minor" (or the "Little Dipper")
Needed: Stellarium set for your location; an
outdoor location facing north.
Again locate Polaris on Celestia for your location at a
to observe it outside. With the constellation lines and
turned on, notice that Polaris is one star in a constellation
"Ursa Minor." This constellation is also commonly known as
"Little Dipper." From the screenshot above, you can see
pattern looks a little like a miniature version of the Big
observe the Little Dipper at night. Several of the stars
constellation are not particularly bright, so you may have to
to see all of them, particularly in an area that is not ideal
There are actually a couple of other star
patterns that feature a dipper shape and are sometimes confused
the Little Dipper. The first is found in the constellation
and the second is a star cluster known as the Pleiades near the
constellation Taurus. Both are wintertime constellations
Northern Hemisphere, but neither are near Polaris or the Big
people mistake the circled portion of Orion for the Little
because of the shape, and because the stars appear relatively
bright than those of the Little Dipper.
above is a screenshot showing both patterns circled. It
represents December 20 of the current year near Raleigh, North
the pattern in Orion indicated by the red dots in the screenshot
looks very much like a pot with a handle at night and is very
mistaken for the Little Dipper. It is sometimes also
the Big Dipper.
is a closeup of the constellation Orion. The stars
that are sometimes mistaken for the one of the dippers are
The Pleiades is a star
cluster that features several bright spots of light indicated by
red dots. When viewed with the naked eye, this pattern is
faint and very small, but it does look very much like a tiny
well. This group is sometimes called "The Seven Sisters"
Greek mythology. You can read an interesting article on
Pliedes, sometimes called "The Seven Sisters" are located in
and although the appear to be small and fairly faint,
they do form
what looks something like a miniature verions of the Big
sure not to confuse the patterns in Orion or the Pleiades with
with the "real" dippers. (You won't once you learn where
"real" ones are found.) Again, remember that the real
Dipper (Ursa Minor) will be found near the Big Dipper (Ursa
both are always in the northern sky.
Locate the pattern in Orion and the Pleiades where you live
Stellarium. They are visible in the winter months in the
Hemisphere and in the summer months in the Southern
(Going to about December 20 will work in the Northern
Next, if it is the right time of year, see if you can
these objects outside.
should now already know two constellations on sight - Ursa
Ursa Minor, as well as the very important Polaris.
working with Stellarium, you have almost
noticed that there
are a lot more constellations shown. But why these
and not others?
stars are where they are, and the overall sky pattern is
the same wherever it is viewed. However, just about
culture that has
taken time to look into the sky has identified certain stars
part of their culture. The Greeks, for example, imagined
the characters from the stories of their gods and goddesses in
patterns. Other cultures saw other objects. By
on Constellation Art in Stellarium's bottom toolbar,
see how some
cultures have matched the patterns to the names.
example, Ursa Major means "great bear" and Ursa Minor means
bear." Now we'll admit that The Science Notebook staff does not
see bears in either constellation, but according to Wikipedia,
different cultures have. Regardless, both are recognized
constellations. (We do see the dippers, though...)
can also view constellation art from other cultures by
art. You do this by clicking on the "Sky and Viewing
button on the left toolbar and then "Starlore" in the window
Several Major Constellations
So far, we have seen that the stars move in one
pattern. Because the pattern shifts a little bit each
after a year, we would have seen all the stars visible to us
naked eye. As the star pattern advanced through the
ancient star observers began picking out patterns of stars
within the big pattern that reminded
them of animals, ancient characters in mythology, or other
objects. They could use these parts of the sky pattern
easy to remember to help them follow the movements of the
sky. It also helped them to track the passing of the
year. We call these patterns constellations, and just
ancients, we can use them to help us find our way around the
Now it is time for you to
begin exploring on your own. As usual,
we will begin with Stellarium, but you are encouraged to get
and view as many of these constellations as possible on your
You won't be able to see all of them at any one time of the
plan on observing several times a year.
Here we go...
Stellarium set for your location; an outdoor location for
Set up Stellarium for your current location and date. Move
in time to night time and then slow down to normal speed.
Constellation Lines, Constellation Labels, and Constellation Art
the bottom toolbar.
Now start scanning the horizon for the constellations listed
- Ursa Major
- Ursa Minor
How many are visible at this
Advance about two hours at a time and continue searching.
Can you see any more?
How many could you view overnight on the day you are doing this?
for those you cannot find, open the search window and type in
of the constellation. When you press enter, Stellarium
you to where that constellation is located. It may take
you up in
the sky, and if so, that means you missed it when you did your
eyeball search. However, it may
point you down to the ground. If so, that means that this
constellation is actually below the horizon.
are locked on to that constellation, speed up time until the
constellation becomes visible. You will see it rise at
(assuming that it is visible in your hemisphere), but it might
set during the day. If it does, then you should try to go
six months, and you should be able to see it at night.
If the constellation is always below the ground where you are,
it is never visible from your hemisphere.
Do you see how you can use Stellarium to help you plan your
as time permits, start paying attention to what is visible at
your location, and begin learning to recognize these important
constellations in the sky at different times of the year.
Other Tools for Finding Things in
the Night Sky
you can locate Polaris and a few of the constellations on your
can begin to identify other constellations. If you are
enough to have a laptop you can take outside, you can use
"Night Mode." But if you don't have a laptop, there are
several other free or inexpensive tools you can make or
planisphere is a simple chart you can adjust for your date and
as to be able to see things in the night sky. If you live
28 and 48 degrees North latitude, you can visit this website to
download and print a do-it-yourself planisphere:
are full instructions on how to make and use the
(There are also a number of other sites offering planisphere
different latitudes free for downloading. Try searching
(You can also purchase a ready-made
planisphere at many museum shops or school supply stores, as
online, but why not save your money?)
are a number of sites that will produce star charts customized
location, date and time, all for free. Many of these may
printed out and taken outside with you. Here are a couple
This one is updated every month, is good for beginners, and is
excellent for outdoor use:
Sky and Telescope
magazine lists a number
of sources for star charts, including their own charts.
Your Local Library
the Internet age we tend to forget about all that is available
local library. Take a look in both the adult and juvenile
sections for good books on observing the night sky. You
that some are much more complicated than you need, but you
able to find at least one or two that you can use. Armed
these resources you can take outside, you should be able to
locate things in the sky without having to rely so much on
But we're not through with Stellarium just yet.
it all Together
If you have done the outside portion of these
activities, you should
now have a pretty good feel for how to find your way around
sky. In this final series of activities, we will put
we have learned so far together so that you can become an
stargazer. When you finish these exercises, you should
be able to
pinpoint individual stars, planets, and other objects in the
Individual Stars in Their Constellations
There are far too many stars to learn all their
names, but there are a
few that it would be well to learn and to associate with their
constellations. Let's take a look at them...
Stellarium set for your location; an outdoor location for
Repeat the method you used with Stellarium to locate the
to locate the indivdual stars listed below. For each one,
is a part of a constellation, identify the constellation to
belongs and make a note of when it could be seen at night where
live. You will use this information in the next activity.
Try to observe as many of these
stars as possible in the night sky.
Individual Stars by Altitude and Azimuth
Needed: Stellarium; astrolabe with support (see
flashlight; red cellophane (optional); planisphere or star chart
(optional); outdoor location for stargazing; information on the
from the last activity.
we'll take care of a couple of odds and ends...
will need some sort of support for your astrolabe at your chosen
location. If there is a picnic table, wall, or other
support, you can use that, or you can mount your astrolabe on a
tripod. If you don't have a tripod, you can mount the
astrolabe on top of a long
stick sharpened at the other end. If you use the stick,
are at your site, you can push the point of the stick into the
ground. (You can use a small stake to make the hole if the
for the larger support if you need to. You can also use
stakes to brace the support.) Regardless of what you use,
important that the base of the astrolabe be level so that
altitude angles will be correct.
Since you will be using the
astrolabe at night, you will need a flashlight to help you read
numbers. However, a bright light will make it more
you to see the sky, even after you turn it off. This is
different cells are used by your eyes to see in bright and dim
light. To minimize the effect of a bright flashlight on
ability to see at night, you can fasten a piece of red
the front of the flashlight. The red light will still be
for you to read the scale on the astrolabe, but it won't affect
night vision as much as white light. (HINT: Some
surplus and hiker's flashlights come with a red filter.)
Now we're ready to get down to business.
Pick a date and time you can go outside to watch the stars, and
set Stellarium for the date and time you have chosen.
locate several of the stars from the list in the previous
are visible at the date and time you have selected. For
you select, click on the star and notice the information in the
left had corner of the screen for that object. Notice that
azimuth and altitude are both included in that
for Az/Alt:...) These measurements are given in
minutes(') and seconds("), and are very precise.
so you'll know, a degree can be divided into 60 minutes, and a
can be divided into 60 seconds. This is important to
and others who need this much accuracy, but we can do with just
You may notice that the seconds portion for
each star is changing as you watch. This is because the
and altitude is changing over time as the star moves through the
(or more properly, as the earth turns underneath). Watch
enough, and the minutes and degrees will also change. The
exception to this is Polaris since it is directly over the north
the Earth's axis and so appears to be completely
even Polaris moves a little bit, so its position does change
slightly over the course of the night - just not enough for it
matter to us.
For our purposes, just write down the azimuth and
altitude in degrees only for each star you plan to locate.
astrolabe is probably only accurate to nearest degree, so you
need to worry about minutes and seconds here. Also record
time of the reading.
If you need to sketch out the surrounding
stars and horizon so that you can find these stars as you did in
last activity, go ahead and do so. Or, if you have begun
star chart or planisphere, you can use them to locate the stars.
the date you have chosen, go to your stargazing site with your
astrolabe, and flashlight (and charts or planisphere if you have
them). Allow just a little time before the time you plan
to begin viewing to
set everything up.
Set up your astrolabe and locate Polaris
using the pointer stars on the Big Dipper. Move the azimuth
that it is lined up with Polaris. It is now oriented to
make sure that the weight on your altitude scale is
hanging freely, and that when the straw is horizontal, the
scale reads zero degrees. Now sight Polaris through
straw and note
the angle on the scale. It should match the altitude angle
your location, and it should not change over time. In
altitude of Polaris is a measure of the latitude at your
matter where you are in the Northern Hemisphere. Neat,
at the time you have chosen, locate each of the stars on you
list. Use the astrolabe to determine the azimuth and
each. How closely does it match the altitude and azimuth
predicted by Stellarium? If you have worked carefully, it
be very close in each case - within a couple of degrees. If it
by a little bit more than that, your time might be a little off,
your astrolabe might not be completely accurate.
If you results are only a little off, check the following:
- Verify that north (0 degrees) on your astrolabe azimuth
scale is pointed directly at true north as determined by
that the weight and string on your altitude scale are able to
freely, and that the altitude scale reads zero when the straw
- Verify that the time you observed each object was the same
time you recorded the altitude and azimuth on Stellarium.
all of these are OK, you may need to go back and check to make
that your location on Stellarium is correct and try again on
night. Be patient, and get help if you need it. This
may be a little challenging to figure out at first, but it will
work, and once you "get it", it will seem positively easy!
Planets by Altitude and Azimuth
Needed: Stellarium; astrolabe with support (see
activity); flashlight; red cellophane (optional); planisphere or
chart (optional); outdoor location for stargazing.
Pick a date and time you want to go outside and locate a
Set Stellarium for that date and time. Move around the
and see whether you spot Venus, Mars, Jupiter or Saturn.
click on that planet (or planets) and note the azimuth and
(just in degrees), as well as the time. You might want to
where the planet is supposed to be in relation to other stars,
it on a printed star chart.
On the date you selected, go to your
location just a little before time to observe. Set up your
astrolabe as you did before and orient the azimuth scale to true
Use the astrolabe to go to the predicted
azimuth and altitude for the planet at the time you have chosen.
where you expected it to be, or at least close enough so you can
that it is where it is supposed to be in relation to the stars?
so, excellent! If not, check for the same errors in the
activity. Also, don't be afraid to ask for help from
is familiar with the sky. This will work once you get the
it, and it is well worth the effort. And once you have
out to find objects using the altitude and azimuth, you can
anything that is visible to you.
Stuff to Try
you made it this far, you should now be able to find anything
visible with the naked eye in the night sky. Here are
things to observe:
- These are the massive
dust clouds, many of which are thought to be the remnants of
stars. Stellarium will label them for you, and you can see
whether they are visible outside. If so, they will appear
stars to the naked eye, except that they might appear to be a
- Stellarium will also
label these for you
as well. These are collections of millions of stars much
Milky Way galaxy in which we live.
- These are massive
clumps of frozen gases and ice that orbit around the sun.
become visible when they get near to the sun may usually be seen
have a long wispy tail. Many of these are visible with the
eye, but you have to know where to look. The Sky and
websites will provide information on when and where
comets are visible.
The Milky Way
- The Milky Way
is our home
galaxy. We are inside a massive collection of millions of
even though we can only see several thousand of them. But
clear, dark, and moonless night, it is possible to see many
more in the form of what looks like a wispy cloud going across
or a vapor trail from a jet that is just about gone. In
this cloud is one arm of the Milky Way galaxy in which we
However, this arm contains many millions of stars. It is
visible on Stellarium, but you can see it, and once you do, head
outside and see if it is visible in your location.
You can observe the phases of the moon, as well as times of
and moonset on Stellarium, as well as outside almost
Follow the moon through its changing phases and times of rising
These pages have attempted
to tell you how and where to find things in the night sky with
your two eyes. We have mentioned the stars,
planets, galaxies, nebulas, and comets, but have really said
little about what these things are. By all means use your
library, follow the links found here, or do your own online
learn more about these magnificent objects. This will make
things you see far more meaningful.
You should also learn what a light year is so that you can get
an appreciation for just how big our universe is.
can extend the reach of your eyes with a good pair of
binoculars, or a
good telescope. With either, you can see the planets as
really are, the individual stars of the Milky Way, and of
surface of the moon, but having spent the time to learn the
like the ancient astronomers, you will know just when and where
Screenshot of Celestia showing
one of Mars' two moons, Phobos, with Mars in the background.
if you enjoy Stellarium, there is another great free and open
program out there called Celestia. You can get it at:
Stellarium, Celestia is really not so much of a planetarium
it is a space simulator. Celestia allows you to take a
of the universe using great photographs and graphics, and
because it is
open source, there are many add-ons available that will let you
various real and fictional spacecraft in orbit. There are
educational scripts that are great learning (or teaching)
tools. A tour of the
solar system is included, but there are many others available as
add-ons, and all are free. There are also many educational
The sky is truly the limit!
And there's lots more to see and do on our Experiment Pages
or you can
visit The Science Notebook Home