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2. Scatter a few beads on the sheet of latex (this represents matter that is near the black hole). Make sure they are spread out to all parts of the sheet.

3. Gently place the ball bearing onto the sheet of latex (this represents the black hole). Try not to let it bounce! If you don’t have a ball bearing, gently push down on the center of the sheet with the eraser end of a pencil.

4. Explain what happened to the matter when the black hole was put into place. Why did this occur?

5. What would happen if the ball bearing was heavier (or if you push harder on the pencil)? What physical analogy to the black hole may be made?

Aluminum Foil, Balloons, and Black Holes

This activity will allow students to conceptualize what happens when a star collapses into a black hole, and to gain the following understanding: whatever the mass is inside a black hole, it is not made up of matter as we know it. It is not protons, neutrons, and electrons. They will also get to practice their skills involving exponential notation, circumference, volume, and density!

drawing of shrinking balloon


  • Round balloons
  • Aluminum foil
  • Balance or scales (best if can measure to at least 0.1 grams)
  • Cloth (or flexible plastic) tape measure
  • Student worksheet

Teacher Notes:

Before you begin the activity, the following is required:

  • review the life cycle of a massive star
  • discuss what a black hole is and introduce the concept of an event horizon
  • derive the equation for the event horizon radius (also called the Scwarzchild radius) from the Newtonian escape velocity equation
  • prepare students to consider mind-blowing concepts: something with no size, but with mass; an imaginary surface which once you cross inside, you cannot get back outside it ever again.

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Imagine the Universe is a service of the High Energy Astrophysics Science Archive Research Center (HEASARC), Dr. Alan Smale (Director), within the Astrophysics Science Division (ASD) at NASA's Goddard Space Flight Center.

The Imagine Team
Acting Project Leader: Dr. Barbara Mattson
All material on this site has been created and updated between 1997-2012.

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