SESKStuff Everyone Should Know
SESK: Stuff Everyone Should Know · sesk.info/astro-lensing-multiple-images

Why can one background object appear as several lensed images?

Its light follows multiple curved paths around foreground mass.

Start playing free

  1. The source physically splits
  2. Light reaches us along different paths ✔
  3. The telescope copies pixels

Why: A foreground mass curves spacetime and deflects passing light. Different routes around the lens can deliver several distorted views of the same source.

Huh, didn't know that: Gravitational lensing can also magnify sources too faint to observe directly.

The dad joke
The quasar had several images because gravity kept changing the route.
Like this card?
Play the game

References

Answer: Light reaches us along different paths. A foreground mass curves spacetime and deflects passing light. Different routes around the lens can deliver several distorted views of the same source.

  1. Hubble's Gravitational Lenses science.nasa.gov/mission/hubble/science/universe-uncovered/hubbles-gravitational-lenses
    the gravitational lens can produce multiple images of the same object
    Checked 2026-10-10.

Think this answer is wrong? Tap "Challenge this answer" on the card in the game and tell us why.

Test yourself in the game

Astronomy & SpaceHow can gravitational lensing reveal dark matter in a cluster?Astronomy & SpaceWhat alignment can turn a lensed galaxy into an Einstein ring?Astronomy & SpaceWhat happens when a foreground star microlenses a background star?

That's stuff everyone should know.