RE: It's all relative!

• Subject: RE: [amsat-bb] It's all relative!
• From: "Reicher, James" <JReicher@xxxxxxxxxxx>
• Date: Fri, 30 Aug 2002 08:36:28 -0500

```I'd call that a mind-expanding revelation!

73 de N8AU, Jim in Raymore, MO

-----Original Message-----
From: Stacey E. Mills [mailto:w4sm@cstone.net]
Sent: Thursday, August 29, 2002 9:27 PM
To: amsat-bb@AMSAT.Org
Subject: [amsat-bb] It's all relative!

OK  Maggie and Tom,  I wanna play too!!!

I used to do this with my kids.  I called it how fast are you moving when
you're standing still?

Tom has covered the earth's rotation on its axis and its motion around the
sun, but there are at least two more interesting reference frames, and the
speeds keep going up!!

The Milky Way galaxy is approximately 100,000 light years in
diameter.   The sun is about 30,000 light years from the center. Thus, in
one trip around the galaxy, the sun covers 60k * PI light years.  A light
year is 9.46e12 km, so that's 1.78e18 km for the sun to orbit the galaxy
once.
It takes about 226 million years (give or take a bit) for the sun to do
that, and of course it pulls the earth and the rest of the solar system
along for the ride.  Crunching the numbers shows that the sun / earth's
speed relative to the center of the Milky Way is 250 km/s.  !!!   That's
approximately 25 times AO-40's speed at perigee.

...and of course the universe is expanding such that the separation rate
for two galaxies is directly proportional to the distance between them. So
from the point of view of someone in a galaxy on the other "side" of the
universe, the earth is retreating at nearly the speed of light, or about
30,000 times the speed of AO-40 at perigee.

--
_______________________________________________________________________
Stacey E. Mills, W4SM    WWW:    http://www.cstone.net/~w4sm/ham1.html
Charlottesville, VA     PGP key: http://www.cstone.net/~w4sm/key
_______________________________________________________________________

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