When you think of exploring astronomy, you probably think of using a telescope to view the moon, planets or other objects in the night sky.  It is true that many great discoveries have been made since the invention of the telescope.  For example, one of the first astronomers to use a telescope to study the heavens was the great scientist Galileo.  However, before the telescope, people observed the night sky with just the naked eye, and their observations laid the groundwork for the discoveries that would later be made.

For many centuries before Galileo, people who studied the stars observed that most of them seemed to move through the sky in a fixed pattern, almost as though they had been painted on the inside of a giant ball surrounding the earth.  This pattern appeared to rise in the east and set in the west every night, but always in the same pattern.

A few of the stars, however, seemed to slowly move around the sky in paths of their own.  These stars were called "wanderering stars."  The ancient observers identified five such wanderers and named them Mercury, Venus, Mars, Juipter and Saturn.  Still, as far as everyone knew, they were just stars, like all the others.  They just somehow managed to move around on their own and would sometimes be brighter than at other times.

But when Galileo pointed one of the first telescopes at a couple of these planets, he made some amazing discoveries.  Venus was not just a bright star - it was actually round and looked very much like the moon.  In fact, over time it would actually go through phases just like the moon, which explained why it looked brighter at some times than at others. And when Galileo first looked at Jupiter, he saw that it was round as well.  But even more amazing, Galileo saw that Jupiter had moons of its own circling the planet.  These wandering stars were not stars at all.  Galileo realized that he was actually seeing other worlds!

Telescopes kept improving and many more discoveries have been made ever since.  Today, we have modern observatories on earth and space telescopes such as Hubble.  Yet as important as the discoveries made by telescopes are, they never could had been made without many centuries of careful observations of the sky without telescopes.

In the activities that follow, you will learn how to observe and identify some of the stars and constellation (or patterns of stars) in the night 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 moon's phases.  You will do this by using a free computer program called Stellarium, a planisphere, and a simple homemade instrument called an astrolabe.  You will do all of this step by step.  In some cases you may already know much of what is presented here, and if so, you can skip over to the things you don't.  But if you are willing to take the time to work through these activities, you can become a competent observer of the skies without a telescope!

These activities assume that you don't have someone with you that can help you locate the stars.  If you do have someone who can help you, so much the better.  Also, if you work together with a group of friends, this will be a lot more fun.

Some of the outdoor activities cannot be done where there is a lot of artificial light.  If you live in the city, much of what you might want to see will be made invisible by bright outdoor lights.  However, using Stellarium, you can at least see what you are missing.

Finally, because The Science Notebook staff is located in the Northern Hemisphere, many of the outdoor activities can only be done in the Northern Hemisphere.  However, the same principles can be applied to the Southern Hemisphere as well.

So let's get started!

Stellarium will let you view the night sky on your computer as it appears outside no matter where you are.  This can be very useful if you live in a city where bright lights keep you from getting a good look at the night sky, or if the weather happens to be bad.  In addition, Stellarium will let you view the sky at some past or future time, or from a completely different location.  It will also allow 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 some other objects to give you great closeup photographs.

Interested?  Well, to get a copy of Stellarium, go to the Stellarium website at:

From there, you will find a link that will let you download the program for Linux, Mac or Windows. You should also download the PDF Stellarium User's Guide.  Once you have downloaded the install program and User's Guide, install Stellarium on your computer. 

NOTE:  If you are not sure how to download and install programs, get someone to help you!  You need to follow the instructions for your operating system in the User's Guide.  Unfortunately, we can't give you step by step instructions here because they are different for each system, and because the program is constantly being updated.

Once the program is installed, you'll need to configure it for your home location.  You'll need to set the date and time and specify whether you live in an area that uses Daylight Savings Time.  You'll also 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 activities that follow, a nearby city will be close enough, but if you are not near one of the listed cities, you can enter your latitude and longitude.  You can locate your latitude and longitude online or get it from a GPS unit. 

There are several other settings that you could change, but for now, all you need to do is get your default location and time right.

When the program is properly installed, you should be able to see what's outside from your computer screen.  If it is day, you will see the daytime sky.  If 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 basics.

It is probably better (but not absolutely necessary) to do these activities after dark so that Stellarium will start with the nightime sky.

Materials Needed:  Stellarium installed and configured for your location; the Stellarium User's Guide.

Procedure:  Start Stellarium.  If it is day time, press [CTRL] and [=] together.  For each time you press them, time will advance one hour.  Press until the time is night and you can see the stars.

Now, hold the left mouse button down and drag your mouse to look around the sky.  Take some time to explore.

Next, if you have not found them already, you should locate the usually invisible toolbars at the left and bottom of the screen.  If you move your mouse down near the bottom left of the screen, the bottom toolbar will appear, and if you move your mouse to the lower left hand side, the left toolbar should become visible.

Let's start with the left toolbar and explore a bit.

When you move your mouse to the lower left edge of the screen, the left toolbar will become visible with six icon buttons.  From top to bottom, they are:

As you mouse over each button, it will identify itself.  Clicking on any button will open a new window that will allow you to change settings.  Let's see what they do...

Location

Click on the Location button to open the Location window.  This window will allow you to set your default location (which you should have already done), either by entering your latitude and longitude or by selecting a nearby city.  You can also select another location to view by (1) entering another latitude and longitude (2) choosing another contry or city, or (3) clicking on the map.  Try using each of these methods to move around the world to other locations.  You can always return to your default location, but if you get stuck, when you reopen the program the next time, you will be back to your default location.

Date and Time

The Date and Time Window will let you move ahead or backward to any date or time.  As you change the date or time, you can see the changes in the night sky on the screen.  Try it.  (Don't worry about resetting the time before you close the program.  The next time you open the program, it will reset to today's date and time.

Sky and Viewing Options

The Sky and Viewing Options window allows you to adjust a number of different viewing options including changing the landscape.  If you want to change the default landscape, feel free.  Otherwise, you probably shouldn't change any settings here until you get to know the program a little better.

Search

The Search window allows you to look for any object.  Type in "moon" and see what happens.  (If you click on any object in Stellarium, including some below the horizon that are not visible, it will be surrounded and identified in the upper left hand corner of the screen.  To make this information go away, just right click once.)

Configuration

The Configuration window has a lot of settings that you don't need to worry about until you become more familiar with Stellarium.  These are described in the User's Guide.

Help

The Help window has a lot of really useful information.  It lists many keyboard shortcuts that are very useful. These are also listed in the User's Guide, and you might want to print them out for handy reference, but you can see them at any time just by clicking the Help icon.

Bottom Toolbar

Now let's take a look at the bottom tool bar.  When you move your mouse down to the bottom of the screen near the left hand side, the bottom toolbar appears with nineteen buttons that turn various features on or off, or toggle between two different functions.  We'll cover these from left to right.

Constellation Lines
Constellation Labels
Constellation Art

The first three buttons show or hide the imaginary lines representing constellations, labels for the constellations, and some neat artwork that shows what each constellation is named for.  Try turning each one on and off.  You can have more than one on at the same time. 

Move around a bit to explore the sky with each of these buttons turned on. 

Equatorial Grid
Azimuthal Grid

These buttons will turn two different imaginary grids on or off.  These grids are used to locate objects in the sky, and you can display one or both at the same time.  In the explorations on this site, we will 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?

Ground

This button will show or hide the landscape.  Hiding the landscape will allow you to see objects that are actually below the horizon.  Try it.

Cardinal Points

This button will turn the cardinal directions - north, south, east or west - on or off.  These directions will help you get your bearings when you start studying the sky.

Atmosphere

This button simulates the haze near the horizon.  You can turn this off so you can see the stars near the horizon much better, but in many 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. 

Nebulas

This button will label the location of nebulas when turned on.  Nebulas are huge clouds of dust and gases.  They are often not visible without a telescope, and the ones that are will appear as somewhat fuzzy stars. 

Click this button on and look for the labels.  What you see displayed will depend on your local time and location, as well as the time of year.

Planet Labels

This button will label the planets.  Toggle it on and move around the sky to see whether you can find any planet in the sky.  (Hint:  More planets are usually seen around sunset or sunrise than late at night.)

Equatorial/Azimuthal Mount

This button is used for one of Stellarium's advanced functions - automatic telescope control.  Click this one on and off to see the effect, but for our work, we're not going to need it, so we'll leave it off.

Center

If you click on any star or other object, it will be identified and labeled.  If you then click on this button, that object will be centered in the screen.  Try it with several stars.  As mentioned above, you can remove the label by right clicking.

Night Mode

If you click on this icon, it will turn on a dull red background on the ground.  This is useful if you have Stellarium on a laptop you can take outside with you.  Try it.

Full Screen/Window

This toggles between a full screen view and a window.  Again, try it.

Quit

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

These four buttons will really let you have fun with Stellarium.  Each time you hit the Decrease Time Speed button, time begins to run backwards!  Each time you hit the Increase Time Speed, time speeds up ten times faster than before.  Normal Time Rate will show the movement of the sky at normal time, whatever that time is when you click the button.  Clicking Set Time to Now will take you back to the current date and time, just in case you have gotten ahead of yourself.  Take some time to play with these buttons while you watch the sky.

Here are some things to try on your own or with the help of others:

Going Further:  Now that you have seen some of what Stellarium can do, take some time to play with Stellarium.  Be sure to keep the User's Guide handy, and feel free to play with it.  You really can't break anything!

OK, playtime's over! 

Well, not really, but your first step in learning the night sky is to get familiar with how stars move through the sky.  In this activity, you will use Stellarium to see how the stars move over time, and then observe the same thing outside.

Materials Needed:  A computer with Stellarium installed and set up for your location, a clear dark night, paper and pencil, flashlight.

Procedure:  Start Stellarium. Make the following adjustments:

When you are ready, face east and watch the star pattern and advance time one hour at a time through the night.  What do you notice about the pattern?  Are there any objects that don't fit the pattern?  If so, click on them to see what they are. Use the [CTRL] plus [-] key combination to return to around sunset.  Now increase time by pressing the icon (see above) or the [L] key a couple of times.  Watch what happens.  Press the "Set Time to Now" icon on the lower keyboard to get everything back to normal.

Repeat the above while looking north, west and south. and note what you see each time

Now lets see this outside.

On 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 east is in the general area where the sun comes up.  OK, if you already knew that, sorry!]  From that spot, choose a landmark that is easy to see such as a tower, power pole, or tall tree.  You want to be able to return to that same spot and face that same direction each time.

On a piece of paper. make a note of where you are standing and which direction you are looking by the landmark you have chosen.  Pick out a shape within the pattern near the horizon that is made of bright stars and and sketch it by making dots on the of paper.  Include your landmark in the sketch.  This will make it much easier to see any movement in the pattern.  Work carefully and study this spot until you are certain you can remember the pattern.

Go back to that same spot and look in the same direction after one hour, and again after two hours.  Compare the position of the stars with where they were when you started.  What do you see?  Can you see this same pattern on Stellarium?  Does the pattern appear in the same place in the sky on Stellarium as it did when you observed it outside?

What You Saw:  When looking toward the north or south while using Stellarium, depending on which hemisphere you live in, you should have observed that the entire pattern of stars seemed to move in a semicircle, and moving from east to west.  In the Northern Hemisphere, these stars seem to rotate around the star Polaris, also known as the "North Star."  In the Southern Hemisphere, there is no bright star that the rest appear to rotate around.  In other words, there is no "South Star," but the stars do seem to rotate around an invisible point in the south.

You should have noticed that the entire sky appeared to rotate as a single pattern of stars that did not change.  The reason they all appeared to move, however, was that the earth is actually turning on its axis once every twenty four hours, so when the sun goes down and the stars become visible, it looks like they are slowly spinning in a circle above either the north or south pole, depending on where you are.  As the night passes, some stars appear to rise over the eastern horizon as others appear to set in the west, just as the sun and moon do. However, even though all the stars appear to move in a fixed pattern, in reality, it is not the sky spinning, but the earth spinning underneath the sky.

If 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 stars might have appeared slightly different due to your location.  If you were near bright lights, many of the fainter stars werel not visible.  Also, it is not possible to represent the sky on a flat surface such as your computer screen without some distortion.  However, once you get used to matching what you see outside to Stellarium, it will become much easier to find your way around the night sky.

If the sky outside did not look similar, you should go back to Stellarium and verify that your date and location are both correct for the time you are observing and try again.

Going Further:  You can change your location in Stellarium and see how this pattern appears in different locations.  For example, if you were at either of the poles, the stars would seem to trace this pattern in a circle with the center directly above your head because you would be standing on one end of the earth's axis.  You can actually see this if you change your location to near one of the poles by clicking on the location map. 

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 on which pole you choose.  What do you notice about the lenghts of day and night at each of these times of the year?  Do you know why?

Next, change your location to the opposite pole.  Do you see the same star pattern?  You may recognize a small part of the star pattern on the horizon, but otherwise you should see mostly a different pattern.  The reason for this is that the earth itself blocks our view of most stars in the opposite hemisphere.

Procedure:  If you live in or near a city where there are lots of lights at night, it may not be easy for you to do much stargazing, since night lights can obscure all but the brightest stars.  If this is your situation, you may have to just use Stellarium for now, but be ready to stargaze the next time you find yourself in a good dark location.

However, if you are lucky enough to live in an area where there are not that many lights, the number of stars you can see will greatly increase, and you should get ready to learn the night sky.  If you do live near such an area, the first thing you should do is identify a good possible area during the daytime.  This area should be easy to get to and have the best view possible of the sky all around the horizon.  You don't want a lot of tall trees or buildings around if you can help it.  Above all, pick a location where it is safe to get to and be at night.  Never compromise your safety!

Once you have picked what appears to be a good spot, visit it well after sunset to see how it looks at night.  If the view of the sky is good, get ready to do some observing.

Materials Needed:  A magnetic compass; a good place to observe stars outside; flashlight, four rocks, plastic bottles; or some other objects to mark the directions on the ground. 

Procedure:  Take a look at the compass below.  You'll notice that it is marked with the cardinal points - North, South, East and West.  The one you have is probably also marked the same way.  Also notice that other points are also marked, such as North East (NE), South East (SE) and so on.  We'll deal with those later.

Your compass may also be marked off in degrees from 0 to 360.  We'll go into more detail about those later as well, but for right now, notice that North is 0 degrees, East is 90 degrees, South is 180 degrees, and West is 270 degrees.

The compass has a magnetic needle inside that lines up in a generally north and south direction.  It is important to know which end is supposed to point north, and which is supposed to point south.  Most compasses will have a little dot or letter to let you know which end points north.  (You can learn much more about how and why a compass works on our Electricity and Magnetism pages!)

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 Earth's magnetic north and south poles are not exactly lined up with the Earth's axis, so the compass is a little off in most areas.  However, the compass will still give you a pretty good idea about where the cardinal directions are, and that's enough for now.  We'll fine tune things a bit later.

For right now, stand in the spot where you expect to do your stargazing.  From this spot, line up the end of the compass needle that points north with the N on the 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 where 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 should be in front of you.  Place another marker in this direction.  Keeping the compass needle lined up with the N, face right again.  You should now be looking south, and the south end of the needle should be pointed away from you.  Place a third marker in this direction.  Finally, keeping the compass lined up with north, face right again, and you should see the W in front of you, which means you are now facing west.  Place a marker in this direction as well.

Finally, mark the spot where you are standing.  If you have a marking pen, 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 will be easy to find with a flashlight at night from where you were standing when the markers were placed.

What you have done is marked the cardinal directions from exactly where you were standing.  This will help you quickly determine your direction at night when looking at the sky.  However, if you move from that spot, you will have to identify the directions again.  After you get familiar with the compass, you should be able to quickly determine the four directions without any markers.  Just line up the N with the north end of the needle.  When you face north, east is to your right, west is to your left, and south is directly behind you.

Going Further:  Because the Earth's magnetic poles are not exactly in line with the geographic poles, your compass could be off by several degrees.  This is known as magnetic declination, and it has to be taken into account when knowing the right direction is critical.  The direction the compass points is known as magnetic north, while the actual north is known as true north.  The magnetic declination measures how many degrees east or west of "true" north the compass needle is pointing. You can find the magnetic declination for your area by visiting:

For example, if the magnetic declination at your location is "10° W", magnetic north lies 10 degrees west or counter-clockwise from true north.  ("°" is the symbol for degrees.)  Therefore, true north is 10 degrees clockwise from the north point of the compass needle. 

If the magnetic declination is 10° E, magnetic north is 10 degrees clockwise from true north, so true north would be counterclockwise from the north point of the compass needle.

If you were relying on the compass for exact directions, you would need to make this correction, but if you live in the Northern Hemisphere, there is a much easier way than having to depend on the compass!  But before we get to it, we need to learn a little bit about measuring directions.

There are 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 azimuth, and in the next, you'll see how to determine the altitude.  Both are really very easy.

Materials Needed:  Compass card illustration shown here:

Procedure:  A compass card is a circle-shaped card that is either attached to a compass needle and swings or rotates with that needle, or is underneath the compass needle, with the compass needle able to swing over it.  The compass card image shown here shows directions in two different ways.  The traditional way of indicating direction measures it with reference to the four cardinal directions - north, south, east and west.

Locate the letter N for "North" at the top of the circle.  When the "N" or north on this card is actually pointing north, you can determine the direction of an object from where you are by using one of thirty two points.  Starting at North, the next point to the right is "North by East" (NbE), then "North North East" (NNE), "North East by North" (NEbN), "North East" (NE) and so on.

For many centuries, people who sailed the oceans used these points to determine their direction.  Once a sailor learned the points well, it was fairly easy to use them, but they can be a little confusing to learn.

The good news is you don't have to learn them!

Notice that right above the N, there is also a zero and a degree symbol (0º).  If you move your finger around the circle, you will notice that the circle is divided into 360 equal parts.  Each part is called a degree and is represented by the number and the symbol for degrees, "º".  Also notice that every ten degrees is marked by a number showing the number of degrees from north.   Using the degree scale, instead of having 32 possibly confusing reference points with different names, you now have 360 divisions you can identify by just a number.

Why 360º?  Well, that is really a math question, but for right now, you should know (if you don't already) that if we divide a circle like a pie, it is useful to divide it into 360 equal slices, and each of these slices measures one degree. (Not much good if you are hungry, but great for directions!) We also use the degree as a unit to measure the size of an angle, and we will do that in the next activity.

For right now, though, you just need to know that you can indicate any azinuth or direction by so many degrees.  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 should see that you can identify directions much more accurately using 360 degrees 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.

If you can line up north on this card with true north, the direction from your location to any other location can be measured as so many degrees from north.  The direction of an object from your position is known as its azimuth.

A little later on, we'll actually line up a similar circle with north and start locating some azimuths.

Are 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 direction you need to face (the azimuth), you then need to know how high up in the sky to look.  In other words, you have to be able to find the altitude, and that requires us to look at degrees again.

Materials Needed:  Protractor.

Procedure:  In the last exercise, you saw that a circle can be divided into 360 degrees.  when two lines meet at a single point, they form an angle.  Shown below are three kinds of angles.

Any angle can be measured in degrees using a protractor.  You have probably seen one of these before, and they are very simple to use.

All you have to do is to place the hole at the center of the protractor over the point at which the two lines meet, and place one line along the bottom edge.  If the gap between the two lines along the scale is less that one half of the circular scale, the angle is an acute angle and it is less than 90º.  If the gap fills more that half, the angle is greater than 90º, and the angle is an obtuse angle.  You have two scales so that you can measure the angle whether the 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.

The protractor shown below is slightly different from the one above.  You will notice that instead of having to line the angle up at the circle, this protractor allows you to line up one line of the angle with the bottom of the protactor.  (If you don't know how to measure an angle with the type of protractor you have on hand, by all means get someone to show you!

The important thing to remember is that to measure altitude, your angle will always be an acute angle or less than 90º.

Take a look at the diagram below.  The man is looking at a star that is above the horizon.  Just how far above the horizon?  If we imagine a flat line going to the edge of the horizon from the man's eye, and another imaginary line going from his eye to the star, we have an angle.  If we have some way of measuring that angle, we can tell how far up from the horizon we have to look to find that particular star.  The measurement of that angle is called the altitude, and we can find it in a couple of different ways.  

The first way is only approximate, but it will give a rough estimate in many cases.  The man below is holding his arms outstretched with his hands balled up into fists.  Straight to the horizon is 0º.  If the bottom of the man's fist touches the horizon, an imaginary line running to the top of the fist is about 10º.  When he places the fist of his other hand on top of the first, an imaginary line to that fist is about 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 number of fists it takes to go from the horizon to the star or other point in the sky, the altitude can be estimated.

Of course this is only an estimate because nobody has the same size hands and arm lengths, but it should be fairly close for most people.  Try it for yourself and see how close you are to stacking 9 fists when you reach straight up or 90º.

There is a much more accurate way of doing this, and we'll see it in the next activity.

Now you have most of what you need to know to locate any object in the sky 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 device called an astrolabe to locate objects in the sky, and we can too.  We just have to make one, but fortunately, it is very easy to do!

Materials Needed:  Compass like the one shown below (available as a larger image  HERE); semi-circular scale like the one shown below (available as a larger image HERE); wooden base, upright stick; string; small weight such as a nut; clean drinking straw; nails.

Procedure:   Print out the compass rose and circular scale.  Cut out the compass rose and put it aside.

Drive a nail from the underside of the exact center of the square board all the way through the board.  (If you have a drill to pre-drill all holes, that might make things a little easier.)  Take the compass rose and push the point of the nail through the exact center, and push the rose all the way down to the base.   The exact size of the board is not important so long as the compass rose fits.  Line up the N with the middle of one side of the board and glue or tape the compass rose to the board.  This will become the azimuth scale for your astrolabe.

Next, print out the semicircular scale on heavy card stock and cut it out.  If you don't have heavy card stock, glue the paper with the scale to a piece of cardboard and let it dry.  When the glue is dry, cut the scale and glue or tape a length of the drinking straw to the top edge and put it aside.  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 wire, coffee stirrer, or some other straight object that will fit snugly into the hole.  It should be about half the diameter of the compass rose, and it will serve as a pointer.  (The one in the illustration used a length of coat hanger wire.)  Remove it for now.

Now take the same end of the stick that will have the pointer attached.  Carefully place the center of that end of the stick on the point of the nail coming from the base and tap the top of the stick to drive it into the nail.  When driven in, it should be straight.

Place the pointer back into the hole on the side.  If the pointer is loose, you can use some glue to secure it better.  Now twist the stick around so that the pointer sweeps through all 360 degrees of the azimuth scale.  The stick should be just loose enough to turn freely.

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 into the wood.  It should be lined up in the same direction as the azimuth pointer.  The altitude scale should be loose enough so that you can rock it up or down, but tight enough so that it will stay 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 string to 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 it! 

Materials Needed:  Astrolabe; magnetic compass.

Procedure:  Go outside and locate magnetic north with your compass.  Place your astrolabe on a flat level surface such as a table or box.  Next, line up north on the azimuth scale with magnetic north.  With the azimuth scale lined up with north, you can determine the direction (azimuth) of any object from you by turning the stick and noting the direction of the pointer.

Next, pick out several objects such trees, water tower, power lines, a distant radio or cell tower, or roof tops.  Now level the scale so that the straw is horizontal.  It is exactly horizontal when the sring with the weight hanging down crosses the zero mark on the altitude scale.

Turn your pointer to one of the objects selected.  What is its azimuth in degrees?  Next, look through the end of the straw opposite the pointer and move the scale so that you see the top of the selected object through the straw.  Note where the string is on the scale.  This is the altitude of the top of the object in degrees.

Now determine the azimuth and altitude for all of the objects you have selected.  Have someone to check behind you to make sure you are doing it right.

OK, you can put this aside for a bit and we'll get back to some star gazing.  Once we learn how to find north in the night sky without a compass and observe a few constellations and stars, we'll come back and learn how to really use this very useful instrument!

Materials Needed:  Stellarium set for your location; paper and pencil; an outdoor location facing north; magnetic compass.

Procedure:  Start Stellarium, and if it is daylight, advance time to about sunset.  Make sure the cardinal points are turned on and use the mouse to drag the display around to the north, as indicated by the red "N."  Turn the constellation names and lines on. 

Starting at the horizon, begin looking for a constellation called "Ursa Major."  If you don't see the name immediately, look up by using the mouse to drag the sky straight down.  Depending on your location, and the time of year, Ursa Major could be partially under the horizon or high in the sky at sunset.  If you don't have a good view of Ursa Major, speed up time until you can see the sky begin to move.  As soon as all of Ursa Major is clearly visible, slow down 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 of Ursa Major in your area will be different depending on the time of year, time of day, and your location.

Make a sketch of the stars and lines and how they are positioned in relation to the horizon. 

Although the "official name" for this constellation is Ursa Major, it is also sometimes called "The Big Dipper."  This name comes from a series of seven stars within Ursa Major that take on the shape of a dipper.  The screenshot below shows Ursa Major with the stars making up the dipper shape indicated by red dots.  Two of these stars will become very important in the next activity.

You should also mark this dipper pattern on your drawing as well.

Now it's time to go outside and find the real Ursa Major!  Starting at the time showing on Stellarium when the sketch was made, go outside and face north.  Using the sketch you made, can you see the stars that make up Ursa Major?  How about the ones that make up the Big 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 you are able to identify the Big Dipper, Polaris is very easy to find using two 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 true north!

Materials Needed:  Stellarium set for your location; an outdoor location facing north.

Procedure:  Locate Ursa Major for the date and time you plan to observe on Stellarium as you did in the last activity.  Note the position of the stars in the Big Dipper, and sketch them as they appear above the horizon if you need to.  Pay particular attention to the two stars that are opposite of the dipper's "handle."  In the screenshot below, they are marked as green dots.  These two stars are used to locate Polaris, and they are called "pointer stars."

If you imagine a line from these two stars going in the direction of the open part of the dipper, and about five times the distance between these two stars, the next star you will see is Polaris.  The common name for this star is the "North Star."

The neat thing about Polaris is that the direction of this star in the sky is always exactly north. (Polaris is 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 which direction is north.  Unlike the magnetic compass, it always shows true north, and there is never any question of magnetic declination.  Its direction in the sky never changes.

Why is this?

The position of Polaris as viwed from Earth is directly over the geographic north pole.  The Earth's axis, or point around which the Earth rotates, runs from the geographic north pole to the geographic south pole.  When the sky is viewed from anywhere within the Northern Hemisphere, as the Earth rotates, the stars appear to rotate, while we appear to be standing still.  What is actually happening is that the earth is rotating on its axis, and what we see as the stars moving in circles around Polaris is actually the earth turning on its axis.

You may be wondering about now whether there is a "South Star."  Unfortunately for our friends in the Southern Hemisphere, there is one that is close, but it is too faint to be visible in many locations.  The name of the star is Sigma Octantis.  There are several others that are fairly close as well, but not nearly as close to true south as Polaris is to north.

Going Further:  Go back to Stellarium and find Polaris.  Next, speed time up so that you can see the stars move, and you will clearly see that they actually do appear to trace circles around Polaris.

Also, to show that Polaris is directly over the North Pole, set the time in Stellarium for around December 20 of the current year, and use the map to pick a location at or near the North Pole by clicking as near to the top of the map as possible.  Loacate Polaris and speed time up enough to see the stars move.  Two things you should notice are:

You may remember from school that the north pole is in costant darkness in winter and constant sunlight in the summer due to the fact that the Earth's axis is tilted.  The same is true of the South Pole, except that the seasons are reversed.  (So what would you see if you ventured down to the South Pole on Stellarium around December 20?  How about six months later?  Go ahead and try both.)

Materials Needed:  Stellarium set for your location; an outdoor location facing north.

Procedure:  Again locate Polaris on Celestia for your location at a convenient time to observe it outside.  With the constellation lines and labels turned on, notice that Polaris is one star in a constellation called "Ursa Minor."  This constellation is also commonly known as the "Little Dipper."  From the screenshot above, you can see that the pattern looks a little like a miniature version of the Big Dipper.

Now observe the Little Dipper at night.  Several of the stars in this constellation are not particularly bright, so you may have to look hard to see all of them, particularly in an area that is not ideal for observing. 

There are actually a couple of other star patterns that feature a dipper shape and are sometimes confused with the Little Dipper.  The first is found in the constellation Orion and the second is a star cluster known as the Pleiades near the constellation Taurus.  Both are wintertime constellations in the Northern Hemisphere, but neither are near Polaris or the Big Dipper.

The above is a screenshot showing both patterns circled.  It represents December 20 of the current year near Raleigh, North Carolina.

The the pattern in Orion indicated by the red dots in the screenshot below looks very much like a pot with a handle at night and is very often mistaken for the Little Dipper.  It is sometimes also mistaken for the Big Dipper.

The Pleiades is a star cluster that features several bright spots of light indicated by the red dots.  When viewed with the naked eye, this pattern is very faint and very small, but it does look very much like a tiny dipper as well.  This group is sometimes called "The Seven Sisters" from Greek mythology.  You can read an interesting article on the Pleiades HERE.

Be sure not to confuse the patterns in Orion or the Pleiades with these two with the "real" dippers.  (You won't once you learn where the "real" dippers are found.)  Again, remember that the real Little Dipper (Ursa Minor) will be found near the Big Dipper (Ursa Major) and both are always in the northern sky. 

Going Further:  Locate the pattern in Orion and the Pleiades where you live using Stellarium.  They are visible in the winter months in the Northern Hemisphere and in the summer months in the Southern Hemisphere.  (Going to about December 20 will work in the Northern Hemisphere.)  Next, if it is the right time of year, see if you can locate these objects outside.

So far, we have seen that the stars move in one continuous pattern.  Because the pattern shifts a little bit each night, after a year, we would have seen all the stars visible to us with the naked eye.  As the star pattern advanced through the night sky, ancient star observers began picking out patterns of stars within the big pattern that reminded them of animals, ancient characters in mythology, or other familiar objects.  They could use these parts of the sky pattern that were easy to remember to help them follow the movements of the night sky.  It also helped them to track the passing of the seasons each year.  We call these patterns constellations, and just like the ancients, we can use them to help us find our way around the night sky.

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 outside and view as many of these constellations as possible on your own.  You won't be able to see all of them at any one time of the year, so plan on observing several times a year.

Here we go...

Materials Needed:  Stellarium set for your location; an outdoor location for viewing.

Procedure:  Set up Stellarium for your current location and date.  Move ahead in time to night time and then slow down to normal speed.  Turn on Constellation Lines, Constellation Labels, and Constellation Art from the bottom toolbar.

Now start scanning the horizon for the constellations listed below

How many are visible at this time?

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?

Now, for those you cannot find, open the search window and type in the name of the constellation.  When you press enter, Stellarium will take 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. 

While you are locked on to that constellation, speed up time until the constellation becomes visible.  You will see it rise at some point (assuming that it is visible in your hemisphere), but it might rise and set during the day.  If it does, then you should try to go ahead 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 stargazing?

Finally, as time permits, start paying attention to what is visible at night at your location, and begin learning to recognize these important constellations in the sky at different times of the year.

Once you can locate Polaris and a few of the constellations on your own, you can begin to identify other constellations.  If you are lucky enough to have a laptop you can take outside, you can use Stellarium in "Night Mode."   But if you don't have a laptop, there are several other free or inexpensive tools you can make or use. 

Planisphere

A planisphere is a simple chart you can adjust for your date and time so as to be able to see things in the night sky.  If you live between 28 and 48 degrees North latitude, you can visit this website to download and print a do-it-yourself planisphere: 

There are full instructions on how to make and use the planisphere.  (There are also a number of other sites offering planisphere kits for different latitudes free for downloading.  Try searching "planisphere download."

(You can also purchase a ready-made planisphere at many museum shops or school supply stores, as well as online, but why not save your money?)

Star Charts

There are a number of sites that will produce star charts customized for your location, date and time, all for free.  Many of these may be printed out and taken outside with you.  Here are some links:

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

In the Internet age we tend to forget about all that is available at the local library.  Take a look in both the adult and juvenile sections for good books on observing the night sky.  You may find that some are much more complicated than you need, but you should be able to find at least one or two that you can use.  Armed with these resources you can take outside, you should be able to begin to locate things in the sky without having to rely as much on Stellarium.

But we're not through with Stellarium just yet.

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...

Materials Needed:  Stellarium set for your location; an outdoor location for viewing.

Procedure: Repeat the method you used with Stellarium to locate the constellations to locate the indivdual stars listed below.  For each one, if it is a part of a constellation, identify the constellation to which it belongs and make a note of when it could be seen at night where you live.  You will use this information in the next activity.

Try to observe as many of these stars as possible in the night sky.

Materials Needed:  Stellarium; astrolabe with support (see Procedure); flashlight; red cellophane (optional); planisphere or star chart (optional); outdoor location for stargazing; information on the stars from the last activity.

Procedure:  First, we'll take care of a couple of odds and ends...

You will need some sort of support for your astrolabe at your chosen location.  If there is a picnic table, wall, or other suitable support, you can use that, or you can mount your astrolabe on a camera 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, once you 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 ground for the larger support if you need to.  You can also use small stakes to brace the support.)

Since you will be using the astrolabe at night, you will need a flashlight to help you read the numbers.  However, a bright light will make it more difficult for you to see the sky, even after you turn it off.  This is because different cells are used by your eyes to see in bright and dim light.  To minimize the effect of a bright flashlight on your ability to see at night, you can fasten a piece of red cellophane over the front of the flashlight.  The red light will still be enough for you to read the scale on the astrolabe, but it won't affect your night vision as much as white light.  (HINT:  Some military 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.

Next, locate several of the stars from the list in the previous activity that are visible at the date and time you have selected.  For each one you select, click on the star and notice the information in the upper left had corner of the screen for that object.  Notice that the azimuth and altitude are both included in that information.  (Look for Az/Alt:...)  These measurements are given in degrees, minutes(') and seconds("), and are very precise. 

(Just so you'll know, a degree can be divided into 60 minutes, and a minute can be divided into 60 seconds.  This is important to navigators and others who need this much accuracy, but we can do with just degrees.) 

You may notice that the seconds portion for each star is changing as you watch.  This is because the azimuth and altitude is changing over time as the star moves through the sky (or more properly, as the earth turns underneath).  Watch long enough, and the minutes and degrees will also change.  The only exception to this is Polaris since it is directly over the north end of the Earth's axis and so appears to be completely stationary.  But even Polaris moves a little bit, so its position does change very slightly over the course of the night - just not enough for it to matter to us.

For our purposes, just write down the azimuth and altitude in degrees only for each star you plan to locate.  Your astrolabe is probably only accurate to nearest degree, so you will not need to worry about minutes and seconds here.  Also record the 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 the last activity, go ahead and do so.  Or, if you have begun using a star chart or planisphere, you can use them to locate the stars.

On the date you have chosen, go to your stargazing site with your notes, 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 scale so that it is lined up with Polaris.  It is now oriented to true north.

Next, make sure that the weight on your altitude scale is hanging freely, and that when the straw is horizontal, the altitude scale reads zero degrees.  Now sight Polaris through the soda straw and note the angle on the scale.  It should match the altitude angle for your location, and it should not change over time.  In fact, the altitude of Polaris is a measure of the latitude at your location, no matter where you are in the Northern Hemisphere.  Neat, huh?

Now, at the time you have chosen, locate each of the stars on you list.  Use the astrolabe to determine the azimuth and altitude of each.  How closely does it match the altitude and azimuth predicted by Stellarium?  If you have worked carefully, it should be very close in each case - within a couple of degrees. If it is off by a little bit more than that, your time might be a little off, or your astrolabe might not be completely accurate.

If you results are only a little off, check the following:

If all of these are OK, you may need to go back and check to make sure that your location on Stellarium is correct and try again on another night.  Be patient, and get help if you need it.  This will work!

Materials Needed:  Stellarium; astrolabe with support (see previous activity); flashlight; red cellophane (optional); planisphere or star chart (optional); outdoor location for stargazing.

Procedure:  Pick a date and time you want to go outside and locate a planet.  Set Stellarium for that date and time.  Move around the horizon and see whether you spot Venus, Mars, Jupiter or Saturn.  If so, click on that planet (or planets) and note the azimuth and altitude (just in degrees), as well as the time.  You might want to sketch where the planet is supposed to be in relation to other stars, or note 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 north using Polaris. 

Use the astrolabe to go to the predicted azimuth and altitude for the planet at the time you have chosen. Is it where you expected it to be, or at least close enough so you can see that it is where it is supposed to be in relation to the stars?

If so, excellent!  If not, check for the same errors in the last activity.  Also, don't be afraid to ask for help from someone who is familiar with the sky.  This will work once you get the hang of it, and it is well worth the effort.  And once you have learned out to find objects using the altitude and azimuth, you can locate anything that is visible to you.

If you made it this far, you should now be able to find anything that is visible with the naked eye in the night sky.  Here are some other things to observe:

Nebulas - These are the massive gas and dust clouds, many of which are thought to be the remnants of exploded stars.  Stellarium will label them for you, and you can see whether they are visible outside.  If so, they will appear to be stars to the naked eye, except that they might appear to be a little fuzzier.

Galaxies - Stellarium will also label these for you as well.  These are collections of millions of stars much like the Milky Way galaxy in which we live.

Comets - These are massive clumps of frozen gases and ice that orbit around the sun.  They become visible when they get near to the sun may usually be seen to have a long wispy tail.  Many of these are visible with the naked eye, but you have to know where to look.  The Sky and Telescope and Space.com 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 stars, even though we can only see several thousand of them.  But on a clear, dark, and moonless night, it is possible to see many millions more in the form of what looks like a wispy cloud going across the sky, or a vapor trail from a jet that is just about gone.  In reality, this cloud is one arm of the Milky Way galaxy in which we live.  However, this arm contaims many millions of stars.  It is barely visible on Stellarium, but you can see it, and once you do, head outside and see if it is visible in your location.

The Moon - You can observe the phases of the moon, as well as times of moonrise and moonset on Stellarium, as well as outside almost anywhere.  Follow the moon through its changing phases and times of rising and setting.

These pages have attempted to tell you how and where to find things in the night sky with just your two eyes.  We have mentioned the stars, constellations, planets, galaxies, nebulas, and comets, but have really said very little about what these things are.  By all means use your local library, follow the links found here, or do your own online searches to learn more about these magnificent objects.  This will make the 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.

You 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 what they really are, the individual stars of the Milky Way, and of course, the surface of the moon, but having spent the time to learn the night sky like the ancient astronomers, you will know just when and where to look. 

Finally, if you enjoy Stellarium, there is another great free and open source program out there called Celestia.  You can get it at:

Unlike Stellarium, Celestia is really not so much of a planetarium program as it is a space simulator.  Celestia allows you to take a grand tour of the universe using great photographs and graphics, and because it is open source, there are many add-ons available that will let you view various real and fictional spacecraft in orbit.  There are also educational scripts that are great 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 activities available.

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