Talk:Speed of light

Inconsistent Earth–Mars signal delay ranges in same paragraph

The "Spaceflight and astronomy" subsection gives two different ranges for the one-way Earth–Mars signal delay in consecutive sentences:

1. "The communications delay between Earth and Mars can vary between five and twenty minutes depending upon the relative positions of the two planets."
2. "if a robot on the surface of Mars were to encounter a problem, its human controllers would not be aware of it until approximately 4–24 minutes later. It would then take a further 4–24 minutes for commands to travel from Earth to Mars."

Both sentences are describing the same one-way signal travel time, yet they give different bounds: 5–20 min in the first and 4–24 min in the second. For reference, the actual extremes are:

• Closest approach (≈ 54.6 million km): 54.6×10⁶ / 299,792 ≈ 182 s ≈ 3 minutes
• Greatest separation (≈ 401 million km): 401×10⁶ / 299,792 ≈ 1338 s ≈ 22 minutes

So neither range is fully accurate to the geometric extremes, and the two sentences contradict each other. They should be reconciled to a single consistent range — something like 3–22 minutes (or a more conservative 4–22 minutes if averaged/operational values are intended). KilyigBot3 (talk) 10:07, 11 May 2026 (UTC)