Planning an investigation will really get your class thinking like scientists. How will they investigate how many stars can we see from Earth?
Run the activity
1. Plan an investigation around a Big Question. What do the pupils already know about the stars in the night sky?
- Does where you are on Earth change the amount you can see?
- What might stop you from seeing stars?
- How would you count them all?
2. How will the group explore the question? Prompt pupils to explain their ideas, qualify them and refine them based on views expressed by other people. What is their plan for the investigation?
3. Ask the class to imagine they had to present their investigation at a school assembly or to their family, how would they show their action plan?
A galaxy is a huge collection of gas, dust, and billions of stars and their solar systems, all held together by gravity. The stars that we usually see at night belong to our galaxy - the Milky Way. On a clear night, thousands of stars are visible to the naked eye in all directions from the Earth. The darker it is, the greater the number of stars that can be seen. In a town or a city, only the brightest and nearest stars can usually be seen. This Nasa article explains that scientists do not know how many stars are in our galaxy (the Milky Way) because there are too many to count. Their models estimate that there are between 100 and 400 billion stars. Earth is located on the outer tip of the Milky Way and sometimes we can see a misty band of the distant part of the Milky Way. It is possible to see the Andromeda galaxy as another misty patch but individual stars from other galaxies are not visible without using a telescope or binoculars.
The number of stars we can see will depend on how dark it is. Because stars are so far away, the light from street lamps, cars, houses and other sources entering a person’s eyes is usually brighter than the light from a faint star – and it stops the star from being seen. In the day time, even on a dull day, the brightness of the Sun will stop all of the other stars in the sky from being seen.
There are constellations (groups of stars that look like a particular shape). The ones you can see depend on where you are on the planet and the time of year. The Big Dipper is a saucepan shape and, depending on cloud cover, is visible all year round in the UK. The Little Dipper includes the North Star Polaris which is useful for navigating because it has a stable position pointing close to North in the sky.
Watch out for
Some children may believe that the stars are only present in the sky during the night because that is when they can be seen. In the day time, even on a dull day, the brightness of the Sun will stop all of the other stars in the sky from being seen.
Take it further
Children could use https://stellarium-web.org/ to look at the stars and planets in the sky above your school in real time. Apps such as Star Walk also provide an interactive star map for mobile phones and other devices. If children have the opportunity to look at the night sky, they can compare which stars and constellations they can see. The Ogden Trust offers this guidance for running stargazing events or Space camps. Your class could contribute to a Citizen Science Project which monitors light pollution called the Globe at Night. The charity Scopes4SEN also provide free telescopes, solar filters and other things to schools to enable all children to try astronomical activities.
Linked Explorify activities- our recommendations:
Zoom in on a dying star with, Far, far away.
Children could learn about the constellations and hear the story ‘Zoo in the sky’ by Jacqueline Mitton read by a NASA ambassador. They could make a constellation projector to take home or draw their own constellation and create a story to explain it.