1L10.50 • Gravitational Lensing

Photo shows the demonstration used at the University of Texas at Austin.

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Concept:

• Shows how galaxies get gravitationally lensed as their light travels through space to reach us.

Instruction/ Notes:

• Show the “Lensed” image first and ask the students what causes this.
• Then show the “Un-lensed” image and hold the lens over the image (the pointed tip points towards the paper). The students should now be able to see galaxies lensed. The farther you hold the lens from the paper, the better the lensing effect.
• A demo cam will be required for this demo.

Note for staff:

• Make sure the lens is always placed on some insulation to prevent scratches/breaks.
• You may occasionally want to clean the lens, and this can be done using isopropanol and Kimwipes.

Last updated on April 27, 2026