Clear Science!

So we wondered, since sound travels through gases, does that mean you could hear a sound in a nebula? It will have to do with pressure. Pressure is the force per unit area exerted on any object due to the surroundings. Atmospheric pressure on Earth is about 101.3 kPa (kilo-pascals), but it varies up and down a bit depending on the weather.

Absence of pressure is called a vacuum. Outer space is pretty close to a vacuum, being about 0.1 pico-pascals, which is close to zero. Since sound is a wave of pressure, there is a threshold minimum pressure wave humans can hear, and it is about 20 micro-pascals. To hear sound, the surrounding pressure would need to be higher than that, to support a wave of that amplitude.

Wikipedia has a very nice list of significant pressure values, which the list above is partially compiled from.

spacerocks:

(via emmacooper, peyotecoyote)

i am an astronaut. i live in space. i have a space cat. she wears a space suit so she can breathe, meow, and eat her food. she keeps stars on her suit to remind her what she shoots for. she’s a good cat.

The managing director of the Clear Science staff has been teaching at science camp this summer. The rest of the staff has been spending time wishing they had a space cat on staff. (Especially one who shoots for the stars.) More Clear Science! to come.