There Actually Is Sound In Outer Space

You’ve heard it before: In space, no one can hear you scream. That’s because sound doesn’t move through a vacuum, and everyone knows that space is a vacuum. The thing is, that’s not completely true.

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I don’t actually count 1 cycle in 10 million years as “sound”.

What is the lowest ever recorded pitch of infrasound?

mollwollfumble said:

I don’t actually count 1 cycle in 10 million years as “sound”.

What is the lowest ever recorded pitch of infrasound?

Wikipedia lists down to 1 cycle every 15 minutes (0.001 Hz). That might be about the limit with Earthquakes, atmospheric sound and ocean surface. Not sure about internal waves in the deep ocean and atmosphere under conditions of density stratification. A typical frequency for internal waves is sqrt(-g/rho * drho/dz)
Plugging in typical values for the ocean gives 0.001 Hz, I suppose that’s where Wikipedia got it’s figure from.

The tides could be thought of as a pressure wave, infrasound, with a dominant frequency of 1 cycle each 12 hours, 0.000023 Hz.

Lower frequencies could occur on the Sun, perhaps. LPV stars such as Mira variables have oscillations with dominant frequencies down to 1 cycle in 1000 days, 1*10 ^-8 Hz.

mollwollfumble said:

mollwollfumble said:

I don’t actually count 1 cycle in 10 million years as “sound”.

What is the lowest ever recorded pitch of infrasound?

Wikipedia lists down to 1 cycle every 15 minutes (0.001 Hz). That might be about the limit with Earthquakes, atmospheric sound and ocean surface. Not sure about internal waves in the deep ocean and atmosphere under conditions of density stratification. A typical frequency for internal waves is sqrt(-g/rho * drho/dz)
Plugging in typical values for the ocean gives 0.001 Hz, I suppose that’s where Wikipedia got it’s figure from.

The tides could be thought of as a pressure wave, infrasound, with a dominant frequency of 1 cycle each 12 hours, 0.000023 Hz.

Lower frequencies could occur on the Sun, perhaps. LPV stars such as Mira variables have oscillations with dominant frequencies down to 1 cycle in 1000 days, 1*10 ^-8 Hz.

If we treat the sunspot cycle as an example of infrasound, that’s 1 cycle in 22 years, 1.4*10 ^-9 Hz. Most starspot cycles seen on the web are the same length as this, or shorter.