What do they mean when they "supersonic speeds" when they're talking about something in space?

Question

http://news.yahoo.com/s/space/20071228/sc_space/jetsspiralinreversewhirlpoolfromstar

Here's the article, but this isn't the first time I've seen this, what the heck does supersonic speeds mean when you're talking about space?

Answer 1

Here on Earth, 'supersonic speed' means any thing moving faster than sound can travel (~700mph @ sea level).
I think you already knew that...
I'm almost 100% positive that the term 'supersonic' in the article was meant as a reference frame for the average 'lay' person.
It's been determined that many of these jets are moving at close to light speed...
But not everyone knows just how fast that actually is!
I'm pretty sure it's just terminology that most people could grasp...
Cheers!
B

Answer 2

Supersonic means faster than the speed of sound, Mach 1

Answer 3

You're right to question this usage. It is rather sloppy.

The reference is to the speed of sound in dry air on earth, or Mach 1, which, at 70 degrees F is:

344 m/s
1230 km/h
770 mph
1130 ft/s

Answer 4

Properly, they would be referring to speeds in
the 1000 FPS range. But as you're completely
correct in observing, in this case, it's an example
of bad technical writing. All too common nowadays.

Answer 5

This article is talking about a jet of material. It says that the speed of the jet is greater than the speed of sound in the jet. It's not talking about vacuum, where the speed of sound would be meaningless.

In fact, most of space is tenuous gas, and the speed of sound in that gas is perfectly meaningful.

Answer 6

maybe their just giving a term, that we find familiar, to its speed, you know, instead of saying 727+ mph

Bobby said what was needed to be said
"the article was meant as a reference frame for the average 'lay' person."

if you caught the glitch, then I'd say your outside of yahoo's targeted audience (lowest common denominator)

super sonic sounds a bit more impactive than 727+ mph.

I agree though.....its a stupid analogy since sound cannot travel in space and even changes depending on the type of medium it travels in, the surrounding pressure, and the temperature of the medium it travels in.

super sonic:
Speed greater than that at which sound travels, measured in Mach numbers.
In dry air at 0°C/32°F, sound travels at about 1,170 kph/727 mph, but decreases its speed with altitude until, at 12,000 m/39,000 ft, it is only 1,060 kph/658 mph.
*********************************************
my big complaint:
why are we talking about pasta??

Answer 7

It's just a term. It means 750 MPH at sealevel

Answer 8

Hi! Per boli!

Hi! Per bole!

Hyperbole!

and I am not talking about curves.