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Learn about black holes

Learn more about these space mysteries with this quick and easy activity.

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You’ll need

  • Stretchy fabric, such as an elasticated bed sheet
  • Marble
  • Football
  • Tennis ball
  • Magnet
  • A4 Paper
  • Paper clips

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.  

A black hole is an object in space with such strong gravity that nothing can escape from it, not even light. Its boundary, called the event horizon, marks the point where you’d need to move faster than light to break free. Black holes grow by collecting matter, such as gas from nearby stars or even other black holes.  

Black holes don’t ‘eat’ stars, moons or planets. They don’t suck in objects unless they’re very close. From far away, their gravity acts just like any other object of the same size. For example, if the Sun were replaced by a black hole of the same mass, Earth and the other planets would continue orbiting it as usual. The only change would be that it would get much colder without the Sun's light. 

Black holes are invisible, but scientists can find them using special tools on space telescopes. These tools detect how stars near black holes behave differently, such as emitting high-energy light that we can’t see with our eyes. Black holes can be small, even as small as one atom, but with the mass of a mountain. Earth won't fall into one because no black hole is close enough, and the Sun isn’t big enough to turn into one. 

(Source: NASA, 2025) 


Bending space 

  1. Gather everyone and explain that black holes are objects in space with gravity so strong that nothing, not even light, can escape. Their gravity is stronger than any planet or star. You could use the information on this page to explain more about black holes.
  2. Lay a large piece of stretchy fabric flat on the ground or have everyone hold it tight in a circle or square shape. Explain to everyone the fabric represents space. 
  3. Place the marble on one side of the fabric. Explain that the marble represents a small object, such as a planet or star. Ask everyone what happens. The fabric should dip around the marble. This shows how smaller objects create a small bend in space.
  4. Leave the marble in place, then place a football on the opposite side of the fabric. Notice how the football creates a much deeper dip. Explain that bigger objects, such as stars or black holes, create a stronger pull on space. This means more gravity and a stronger bend in space.
  5. Roll a tennis ball toward the football. It will roll into the dip. Explain that smaller objects get pulled towards larger objects due to the stronger gravity, just like planets orbit stars.
  6. Now explain that the area around the football is like the ‘event horizon’ of a black hole. Once something crosses this line, it can’t escape, just like the tennis ball can’t roll back once it gets too close to the football.
  7. Explain that black holes don’t suck things in like a vacuum. They only pull things in if they get too close. Just like the football didn’t pull everything in, a black hole’s gravity only affects objects that get close enough.
  8. Optionally, try adding more objects (such as marbles or tennis balls) to see if they fall toward the football. Explain that if they get too close to a black hole’s event horizon, they can’t escape, but objects far away are not affected. 

Identifying black holes 

  1. Now, ask everyone to get into pairs.
  2. Give each pair a magnet, some paper clips and A4 paper.
  3. One person should turn around, so they can’t see the paper.
  4. The other person should place a magnet under a piece of paper with paper clips on top.
  5. Now, the other person can turn around. The players can’t see the magnet, just like we can't see black holes. But the paper clips will move toward it, showing how black holes affect things around them. 
  6. The player should try to figure out where the ‘black hole’ is by watching the effects on the clips, just like we know black holes exist by observing their effects on stars.
  7. Once they’ve guessed, the two players can swap roles and play again.  

Reflection

This activity was all about black holes. Can you remember what a black hole is? It’s an object in space with gravity so strong that nothing, not even light, can escape. Did the football or the marble make a deeper dip in the sheet? That’s because bigger objects, such as black holes, create stronger gravity and bend space more. Did the tennis ball help you understand how objects get pulled towards black holes?  

Why can’t things escape once they get too close to a black hole? The event horizon means things can’t escape. It's the boundary around a black hole where gravity is so strong, nothing can get away. Once something gets too close, it can't escape, just like how we saw the tennis ball not being able to get back out of the dip of the football.  

Black holes don’t ‘suck’ things in like a vacuum. They only pull things in if they’re very close, like how gravity works with other objects. Did the marble get pulled in? If you're far enough away from a black hole, you won’t be sucked in, and things can keep moving in orbit. The only difference with a black hole is that its gravity is much stronger the closer you get, which is why objects that get too close can't escape, like the tennis ball. If the Sun were replaced by a black hole of the same mass, would Earth fall in? Why not? 

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.

Science

Supervise young people, and only do science activities that are advised and age appropriate for your section. Test activities first, to make sure you’re confident you can lead them safely. Use protective clothing where necessary.

Make it accessible

All Scout activities should be inclusive and accessible.

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