3 ms·

Several times the speed of sound? That is meaningless when there is no media for the sound waves. I think a better unit might be furlongs per fortnight.

hgoel 6mo ago
"several times the speed of sound" is obviously just meant to mean really fast to earthlings in relation to their speed of sound.
- __m 6mo ago
  It’s not a constant on earth either, should have used km/h instead for a relate able number
ambicapter 6mo ago
From TFA: > 2.43 kilometers a second, or 1.51 miles a second, or 5,400 miles an hour, or 8,700 kilometers an hour. > There is, of course, no air and no sound on the Moon, so a "Mach number" doesn't really make sense. But if there were air, the speed would be about Mach 7, seven times the speed of sound.
- roelschroeven 6mo ago
  "If there were air". Air at which temperature though? Th sound of speed, and hence what Mach numbers mean, depends on the temperature of the air. The temperature air would have at the moon's surface? By day or by night? Or the air at Earth's surface? Or at some other altitude?
- SecretDreams 6mo ago
  How many Machs is the earth moving?
jghn 6mo ago
What about giraffe lengths per second?
sandworm101 6mo ago
Well, there is a speed of sound on the moon. Sound does travel through the regolith. If you were standing on the moon you would indeed "hear" this impact as the sound moved up through your feet. It would sound/feel like standing beside a subwoofer.
- throwaway27448 6mo ago
  I wouldn't call that sound but you can call whatever you want whatever you want, I suppose
  - matttttttttttt 6mo ago
    Transverse pressure waves? I still call it sound when I hear things under water. Gas isn't special. When someone knocks on your door, you still say you heard the sound, even though the pressure wave was transmitted through the solid door material (before then being transmised to the gas in the room). Likewise, we still file a noise complaint when the neighbor is throwing a raging party, even though we are feeling the bass as much as we are hearing it.
    - sandworm101 6mo ago
      And many old dogs, who may be totally deaf, can still hear/feel someone knocking on the front door. You don't need ears to detect vibrations.
  - sandworm101 6mo ago
    Like putting your head on a railway track to hear a train? Sound is sound.
    - throwaway27448 6mo ago
      To me, sound is a particular element of human perception. Not all pressure waves are going to be perceived as sound.

hgoel 6mo ago

"several times the speed of sound" is obviously just meant to mean really fast to earthlings in relation to their speed of sound.

__m 6mo ago
It’s not a constant on earth either, should have used km/h instead for a relate able number

ambicapter 6mo ago

From TFA: > 2.43 kilometers a second, or 1.51 miles a second, or 5,400 miles an hour, or 8,700 kilometers an hour. > There is, of course, no air and no sound on the Moon, so a "Mach number" doesn't really make sense. But if there were air, the speed would be about Mach 7, seven times the speed of sound.

roelschroeven 6mo ago
"If there were air". Air at which temperature though? Th sound of speed, and hence what Mach numbers mean, depends on the temperature of the air. The temperature air would have at the moon's surface? By day or by night? Or the air at Earth's surface? Or at some other altitude?
SecretDreams 6mo ago
How many Machs is the earth moving?

jghn 6mo ago

What about giraffe lengths per second?

sandworm101 6mo ago

Well, there is a speed of sound on the moon. Sound does travel through the regolith. If you were standing on the moon you would indeed "hear" this impact as the sound moved up through your feet. It would sound/feel like standing beside a subwoofer.

throwaway27448 6mo ago
I wouldn't call that sound but you can call whatever you want whatever you want, I suppose
- matttttttttttt 6mo ago
  Transverse pressure waves? I still call it sound when I hear things under water. Gas isn't special. When someone knocks on your door, you still say you heard the sound, even though the pressure wave was transmitted through the solid door material (before then being transmised to the gas in the room). Likewise, we still file a noise complaint when the neighbor is throwing a raging party, even though we are feeling the bass as much as we are hearing it.
  - sandworm101 6mo ago
    And many old dogs, who may be totally deaf, can still hear/feel someone knocking on the front door. You don't need ears to detect vibrations.
- sandworm101 6mo ago
  Like putting your head on a railway track to hear a train? Sound is sound.
  - throwaway27448 6mo ago
    To me, sound is a particular element of human perception. Not all pressure waves are going to be perceived as sound.