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SESK: Stuff Everyone Should Know · sesk.info/aero-kepler-transits

How did NASA's Kepler space telescope find planets around other stars?

It watched for tiny dips in a star's brightness as a planet passed in front.

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  1. It watched for stars dimming slightly ✔
  2. It took close-up photos of each planet
  3. It listened for radio signals

Why: When a planet crosses in front of its star, the star looks a tiny bit dimmer. Kepler watched many stars for these dips, called transits.

Huh, didn't know that: Kepler found more than 2,600 planets outside our solar system.

The dad joke
Why did the star blink? A planet walked right in front of it without saying excuse me.
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References

Answer: It watched for stars dimming slightly. When a planet crosses in front of its star, the star looks a tiny bit dimmer. Kepler watched many stars for these dips, called transits.

  1. NASA Science, Kepler science.nasa.gov/mission/kepler
    Kepler detected planets by observing transits, or tiny dips in the brightness of a star.
    Checked 2026-10-10.
  2. NASA Science, Kepler science.nasa.gov/mission/kepler
    leaves a legacy of more than 2,600 planet discoveries from outside our solar system
    Checked 2026-10-10.

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