Empirical Earth · Test It Yourself

The Earth did not fly away while Apollo was in transit

The claim

“Everything is moving, so in three days the Earth would race away and the crew could never get back.”

What is measured

Speed only means something relative to a chosen reference. In the frame that matters here, the Earth-Moon system, the ship, the Moon and home all carry the same huge solar-orbital speed, so it cancels out. What remains is a short hop to the Moon and back, and the Earth stays right where the ship left it.

What would show this is wrong

any Apollo trajectory that had to correct for the Earth’s 30 km/s solar-orbital speed. It never did, because that speed is shared by everything in the Earth-Moon system; the plans corrected only for the Moon’s own orbital motion, and they worked, six times.

Sources

  1. How Apollo reached the Moon. A detailed walk through the translunar trajectory, showing that the craft was aimed at where the Moon would be after the three-day crossing and that the ship car link
  2. The free-return trajectory. Apollo’s early flights used a path shaped so that, with no further engine burn, the spacecraft would swing around the Moon and fall back to Earth on its own; Apol link
  3. Motion depends on the reference frame. A treatment of the Earth-Moon-Sun system showing that the large shared orbital velocity is common to all the bodies and drops out when their relative m link
The full entry, with the working →

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