# How close to the Sun would you have to be to hear it?

The Sun is immensely loud. The surface generates thousands to tens of thousands of watts of sound power for every square meter. That's something like 10x to 100x the power flux through the speakers at a rock concert, or out the front of a police siren. Except the "speaker surface" in this case is the entire surface of the Sun, some 10,000 times larger than the surface area of Earth.

We know what the Sun "sounds" like - instruments like SDO's HMI or SOHO's MDI or the ground-based GONG observatory measure the Doppler shift everywhere on the visible surface of the Sun, and we can actually see sound waves (well, infrasound waves) resonating in the Sun as a whole! Since the Sun is large, the sound waves resonate at very deep frequencies - typical resonant modes have 5 minute periods, and there are about a million of them going all at once.

How close to the Sun would you have to be to hear it with normal human ears?

Lets assume you are in a spaceship similar to what we can produce today, would an astronaut inside the spaceship be able to hear the roar of the sun if that spaceship was in a very close orbit to the Sun?

Would you be able to hear the Sun from Mercury? (Did Mariner 10 or Messenger hear the Sun from that range?)

Is it realistic, in whilst writing Sci-Fi, to say that someone near a star could hear all this noise and energy coming from that star?

• Unless I'm misunderstanding the question, you'd have to be inside the sun's atmosphere, since sound can't travel through a vacuum. Is that the question you're asking? – Morris The Cat Jul 31 '19 at 15:26
• Perhaps I am not explaining myself very well here - I get that sound struggles to move through a vacuum - however energy (of all different kinds) is emitted from the Sun, & there is a point where this energy hitting your spaceship would cause the spaceship to vibrate and thus create a sound - a sound created by the Sun - I am wondering how close you would have to be to hear this? – Jimmery Jul 31 '19 at 15:37
• The question possibly needs further clarification to confirm what source of sound you're looking for. - [kind of an answer: But technically we can 'hear' sounds caused by solar energy hitting stuff here on earth with things like sheet metal expanding and contracting due to heat change from being in the sun...] – TheLuckless Jul 31 '19 at 15:40
• Take a sheet of metal. Put it on the ground in the sun at noon on a clear summer day. Let it become hot. Take an egg, crack its shell and pour the contents on the hot metal sheet. The egg will begin to sizzle, producing the well-known sound of an egg being fried. This is sound produced by solar energy, no spaceship needed. – AlexP Jul 31 '19 at 15:47
• A lot of people will say there is no sound because space is a hard vacuum. To be pedantic, that is not true. The interstellar medium is filled with particles. The speed of sound in it is about 100km/s (source). Still, the density and the frequencies involved are both too low to allow us to hear anything. – The Square-Cube Law Jul 31 '19 at 16:36

We cannot hear the sun at any distance because sound cannot travel through a vacuum. We would need to be within the Sun's atmosphere to hear it, in which case I think we have bigger problems than ear protection.

But I think there are a couple things we actually could hear about the Sun. First, the Sun emits quite a bit of radio which we can easily listen to. Second, if we had a material that could be thin and stop the solar wind, we may be able to hear it. Currently, we can't hear the solar wind on Earth because it gets stopped ~100 miles above us, and we can't hear it in space because most of it goes right through us. But if we had some new material that could be used as the skin of the spacecraft and would block a much higher percentage of solar wind, it may be audible inside the ship. It would sound a lot like being in a car in a windstorm here on Earth. I have no idea how loud it would be at what distance, maybe somebody else can figure that out.

• Someone needs to put a microphone on the sails of the first solar clipper so that people riding inside can hear the wind in their sails... – AndyD273 Jul 31 '19 at 16:05
• @AndyD273 a piezo relay would do. – The Square-Cube Law Jul 31 '19 at 16:06
• @AndyD273 very romantic, that. – Morris The Cat Jul 31 '19 at 19:09
• "I have no idea how loud it would be" - that entirely depends on how sensitive your microphone is. – John Dvorak Jul 31 '19 at 20:06
• Even if you hand-waved away the sound-in-a-vacuum problem, we still wouldn't be able to hear it. OP's quote says the sound waves have a period of ~5 minutes. That's 0.0033 Hz, and human hearing bottoms out around 12-20Hz. – bta Aug 1 '19 at 2:00

You can't hear it regardless of range, contrary to popular belief sound does travel in space. "Hard vacuum" isn't completely devoid of matter so sound waves do travel in fact rather faster than the speed of sound at sea level the problem is that the noises the sun makes have a wavelengths measured in the hundreds of kilometers, these have no meaningful interactions with the human body, we simply can't interpret them.

• The wiki article for the heliosphere you linked to says the speed of the solar wind is 400km/s, and the speed of sound in interstellar space is 100km/s. This is thousands of times faster, not slower than the speed of sound at sea level. – Ryan_L Jul 31 '19 at 21:03
• There's even a physics.stackexchange post with the question, What is the speed of sound in space – James Aug 1 '19 at 1:19
• @Ryan_L Yeah I read "/h" when I looked at it, have edited. – Ash Aug 4 '19 at 11:41