SIGNALS

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The signal that left Earth

Earth sent a spacecraft. How long does a question take to reach it?

Voyager 1, a spacecraft Earth sent, still going in the dark. Teaching picture.

Earth

Voyager 1

0.0 hours of light-time

Earth sent Voyager 1. It is still going. Light to the Moon is about 1.3 seconds. At one light-day, a command takes a day.

  1. Source

    Earth (Deep Space Network)

  2. Medium

    Radio, at light speed

  3. Signal

    A command

  4. Detector

    Voyager

  5. Measurement

    Hours of light-time

  6. Meaning

    Distance is also waiting