What's with Surface speed?

[Kasuha]

Time for me to ask a question.

Surface speeds work well when you're near the surface, but in the interplanetary space they seem to make no sense.

For in stance, I was intercepting Kerbin on return from Duna (rather hasty one but I had enough fuel), my orbital speed was 9171 m/s and (Sun) surface speed 189,751 m/s. What the hell?

I'd expect the surface speed to be the speed of my shadow projected perpendicularly on the surface. Only two things play role here, the Sun's surface rotation speed (which is about 3 km/s according to Wiki) and speed of my projection which should be always smaller than my orbital speed - in the worst case it shouldn't be more than 12 km/s, so where does that crazy number come from?

Or is Sun rotating faster than Wikipedia says? I made only a few sungrazing flights so far but it didn't seem to be so to me.

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Edited December 14, 2013 by Kasuha

[bsalis]

I have noticed this too.

NFI why it is so.

[MBobrik]

no clue saw it when returning from Minmus. Orbital speed lower hundreds m/s surface speed crazy five digit number.

.

EDIT: I believe I know what it is. they don't compute the surface velocity as velocity projected onto the actual surface of the body, but simply by subtracting the rotation velocity at current height, which, if you are significantly higher than the actual surface gives this ridiculous number.

Edited December 14, 2013 by MBobrik

[Kasuha]

they don't compute the surface velocity as velocity projected onto the actual surface of the body, but simply by subtracting the rotation velocity at current height

That seems to be reasonable explanation. Thanks, I don't know if I'd figure that out myself.