Seeing stars

Make a planisphere

A planisphere is a circular star map that shows the brightest stars and constellations we can see from Earth. It helps you to name the constellations you can see, depending on where you are and what time of year it is.

1. Give everyone a set of templates. They should cut out the horizon templates for both hemispheres. They’ll need to cut out the shaded areas in the middle of each template to make the spy window.

This can be tricky – try folding the horizon template over (but not pressing to make a crease) and making a snip in the middle of the shaded area to get you started.

2. Everyone should fold the tab on the left of each horizon template back behind the template.
3. Everyone should glue both tabs, line the horizon templates up with the illustration facing outwards, and use the glued tabs to stick the horizon templates back to back. They should now have a double sided horizon template, which is open all the way through the middle.
4. Everyone should use a split pin to make a small hole through the very middle of the double sided horizon template (in the middle of the circle on the bar across the centre of the template).
5. Everyone should take their star maps, and use a pencil to write a small ‘N’ for north and ‘S’ for south on the front, before cutting them out. The letters will make sure they don’t get mixed up.
6. Everyone should line their star maps up back to back, so that the months line up. It may be helpful to hold the maps up to a light or a window, so you can see through the paper to match up the lines.
7. Everyone should pick a month, and place a dot of glue behind their month, on the back of the map. They can then match the month they chose on both maps, to give them a matched up starting point to glue the maps together.
8. Everyone should glue their maps together, to create a double sided map – one side is the northern hemisphere, the other side the southern hemisphere.
9. Everyone should use the split pin to make a hole in the middle of their star map – it should go right through the north star (Ursa Minor), which is in the middle of the side marked ‘N’.
10. Everyone should slide their star map into their horizon template. The side with the ‘N’ on should be under the northern hemisphere horizon template.
11. Everyone should line up their star maps, so that the line between the months and the stars lines up with the curved top of the horizon template. The names of some months, and the little numbers underneath, should poke out of the top of the horizon template.
12. Everyone should attach the whole planisphere together by pushing a split pin through the holes they made in both pieces earlier. If you’re in the northern hemisphere, this split pin now represents the north star.

Use your planisphere

1. Choose the side of the planisphere that matches where you live. If you’re in the UK, you’re in the Northern Hemisphere.
2. Find the right month (and date) on the outside of the star map, and line it up with the time on the horizon template.
3. The stars visible in the oval window on your star map are the ones visible in the night sky at that time.

These stars are in constellations – these are just groups of stars that people have given names to, often because they look like something. The lines on the planisphere show how the stars are grouped together.

4. Why not practice in pairs? One person should pick a date and time, and set their planisphere. They should tell their partner the date and time, and they should set their planisphere, without looking. They should see if the same constellations are visible.
5. Once everyone’s confident with their planisphere, it’s time to set it for today, and head outside to see what you can spot in the night sky.

Most places north of the equator will be able to see Cassiopeia, Cepheus, Draco, Ursa Major, and Ursa Minor all year round – so see if you can spot them first.

6. Make sure the planisphere is set to the right date and time. Start by looking north, and line the planisphere up so north is at the bottom. If you move round, move the planisphere so the direction at the bottom of the horizon template matches the direction you’re facing.