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Explore gravity in space

Discover what gravity is and how it affects astronauts in space.

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You’ll need

  • Buckets
  • Access to water
  • Paper cups
  • Towels
  • Something to make a hole in the cup, such as scissors

Before you begin

  • Use the safety checklist to help you plan and risk assess your activity. There's also more guidance to help you carry out your risk assessment, including examples.   
  • Make sure all young people and adults involved in the activity know how to take part safely.
  • Make sure you’ll have enough adult helpers. You may need some parents and carers to help. 

Planning and setting up this activity

  • Fill a bucket or container with water until it's about one-quarter full.
  • Place the bucket on a towel somewhere in your meeting place.
  • Carefully make a hole in the paper cup, around 2cm from the bottom.

Gravity pulls things towards Earth and keeps planets in orbit, including the Moon. Some think there’s no gravity in space, but there’s a little. It just gets weaker the farther you go. In space, astronauts experience microgravity, which means gravity is very weak. They float because they’re falling toward Earth but moving so fast forward that they never hit the ground. This is why even heavy objects move easily. Space is a vacuum, meaning no air to slow things down. On Earth, a feather and a hammer fall at different speeds, but in space, they fall the same. The spaceship and astronauts are all falling together, which makes them feel weightless - just like the brief weightless feeling on a rollercoaster drop! (Source: NASA, 2025)

There’s less gravity in space, so living in space has been described as being a bit like standing on your head. With less gravity pushing down on you, fluids tend to pool in the upper parts of your body. This gives astronauts a puffy, red face. On the International Space Station (ISS) the pull of gravity isn't as strong as on Earth. Your muscles don’t need to work as hard, and your bones weaken. Your heart muscle gets weaker, as it requires less effort to pump blood around the body in microgravity. Each crew member has a strict daily exercise routine to make sure they don’t waste away. Astronauts often complain of feeling sick during the first few weeks on the ISS and the body usually takes a little time to adjust. Astronauts often use themselves as guinea pigs to test the effects of space on the body. The results can be used to prepare for long duration space flights, such as a mission to Mars in the future (Source: BBC Bitesize, 2025).

Learning about gravity

  1. Ask if anyone knows what gravity is. We have included some information at the top of this page.
  2. Explain to everyone that you’re going to do a quick experiment on gravity.
  3. Gather everyone around the bucket of water.
  4. Place the cup into the bucket of water and let it fill up.
  5. Cover the hole with your finger to stop the water from coming out, then lift the cup out of the water. The water should stay inside because your finger blocks the hole.
  6. Lift the cup above the bucket and remove your finger from the hole. The water should pour out.
  7. Explain that the gravity pulls the water down, just like it pulls everything toward the ground.
  8. Put the cup back in the bucket and fill it up again. Again, cover the hole with your finger and lift the cup above the bucket. The water stays inside because your finger is blocking the hole.
  9. This time let the cup go and drop it into the bucket. Watch closely—does the water come out while the cup is falling? 
  10. Tell everyone that the water doesn’t come out of the hole as it falls into the bucket. The cup and the water inside fall at the same speed, so the water stays inside!
  11. Ask everyone why the water may not have come out of the hole in the cup this time.
  12. Explain that when the cup falls, both the cup and the water inside it are moving down at the same speed. Since everything is falling together, there’s no extra force pushing the water out of the hole. Astronauts in space feel weightless for the same reason—they’re falling around Earth at the same speed as their spaceship. 
  13. Ask everyone how that experiment would be different if it were to be done in space.
  14. Explain that in space, the experiment would be different because of microgravity. With weaker gravity, the water wouldn’t fall out of the cup and the cup wouldn’t fall into the bucket. Everything, including the cup and water, would float together in free fall, just like astronauts in space.

Gravity in space

  1. Ask everyone to move away from the bucket and gather in a group. 
  2. See if anyone can remember what you’ve just learned and if anyone knows what would happen if the experiment was done in space. The water would stay in the cup and the cup wouldn’t fall into the bucket because there’s weaker/less gravity (microgravity).
  3. Now, ask everyone to get into small groups.
  4. Each group should make a poster or leaflet about how gravity affects astronauts in space.
  5. Give everyone around 20 minutes to create their poster, using any of the craft materials available. 
  6. When everyone's finished, give each group the opportunity to share their poster and facts with the rest of the groups.

Extra activity - How astronauts are affected

  1. After everyone has finished presenting their posters, if you have time, you could have a go at this activity to see how well everyone remembered the facts about astronauts in space.
  2. Tell everyone that you’ll say a statement, and they must decide whether it’s True or False. If they think the statement is true, they move to one side of the space. If they think it’s false, they move to the other space. You can make the game harder by having anyone who gets the answer wrong, being out. The last person in the game, wins. Read out the following statements one by one and have everyone move based on whether they think they’re true or false: 
  • In space, fluids in an astronaut’s body tend to move to the upper part of their body.
    • True – With less gravity pulling down, fluids move to the head and upper body, giving astronauts a puffy, red face.
  • In space, astronauts’ muscles have to work harder because gravity is weaker.
    • False – With weaker gravity, muscles don’t need to work as hard, which is why astronauts need to exercise daily to stay strong.
  • Astronauts’ bones get stronger in space because there’s less gravity.
    • False – Without gravity pushing on their bones, astronauts' bones weaken in space.
  • Astronauts grow taller in space because there is less gravity pulling on their bones and spine.
    • True – Without gravity pulling down, astronauts can grow a few centimetres taller while in space, but their spine compresses back to normal after they return to Earth.
  • Astronauts don’t need to exercise in space.
    • False – Astronauts must exercise every day to keep their muscles and bones strong in microgravity.
  • It takes astronauts a little time to adjust to life in space because their bodies are not used to the weaker gravity.
    • True – Astronauts often feel sick and need time to adjust to microgravity when they first arrive at the ISS.
  • Astronauts use themselves as ‘guinea pigs’ to test how space affects the body.
    • True – Astronauts often conduct experiments on themselves to study the effects of space on the human body.
  • In space, astronauts’ hearts become stronger because they don’t have to work as hard to pump blood.
    • False – In space, the heart gets weaker because it doesn’t need to work as hard to pump blood due to the weaker gravity.
  • The effects of living in space can help scientists prepare for long space missions, like going to Mars.
    • True – Studying how the body reacts to space helps plan for longer missions, such as trips to Mars in the future.
  • In space, astronauts are protected from cosmic rays because the Earth’s atmosphere is still there.
    • False – In space, astronauts aren’t protected by Earth's atmosphere, so they are exposed to harmful cosmic rays. Cosmic rays are invisible waves that can affect astronauts’ health and increase the risk of certain diseases.
  • Cosmic rays are only a problem for astronauts who travel to Mars, not those on the International Space Station (ISS).
    • False – Astronauts on the ISS are still exposed to cosmic rays, and these rays can affect their health.

Reflection

This activity as all about learning about gravity and how it affects astronauts in space. How did this quick demonstration help you understand gravity better? What can you remember about how gravity works in space? The water fell out of the cup on Earth, but stayed inside the cup in microgravity. Could you think of any other fun ways to show how gravity works? 

You also learned about how astronauts' bodies are affected by space. What new things did you learn about gravity in space and how astronauts experience it differently than we do on Earth? Did anything surprise you? Do you think humans could eventually travel to space on holiday or live there? 

Safety

All activities must be safely managed. You must complete a thorough risk assessment and take appropriate steps to reduce risk. Use the safety checklist to help you plan and risk assess your activity. Always get approval for the activity, and have suitable supervision and an InTouch process.

You must run your activities in line with the Safeguarding Code of Conduct for Adults (Yellow Card) and report any concerns to the UK HQ Safeguarding Team.

Scissors

Supervise young people appropriately when they’re using scissors. Store all sharp objects securely, out of the reach of young people.

Sharp objects

Teach young people how to use sharp objects safely. Supervise them appropriately throughout. Store all sharp objects securely, out of the reach of young people.

For anyone who may not be able to move around your meeting place easily, think about creating response cards for everyone. People can hold the response cards up to show their choice, instead of moving to different parts of your meeting place. Make sure to use colours that can easily be identified for anyone who’s colourblind. 

All Scout activities should be inclusive and accessible.

Scouts Space Activity Badge

If you enjoyed this activity, try our other Space activities.