The Galactic Environment of the Sun
http://www.americanscientist.org/template/AssetDetail/assetid/21173/page/2
“Our sun is also in motion. Relative to the average motion of the most commonly measured nearby stars, the sun moves with a speed of about 16.5 kilometers per second, or nearly 50 light-years per million years... The sun oscillates through the plane of the galaxy with an amplitude of about 230 light-years, crossing the plane every 33 million years. However, the sun’s motion relative to the local stellar neighborhood should not be confused with its movement around the center of the galaxy, since the whole solar neighborhood (including the sun) orbits the galactic center once every 250 million years. Just as we do not include the earth’s velocity around the sun when calculating the speed of an airplane (we are only interested in the ground-speed), astronomers do not include the sun’s galactic orbital velocity when describing its local motion.”
That's true, but that colloquilism causes large numbers of astronomers and physicists to incorrectly estimate the Speed of Gravity as being equal to the Speed of Light...whereas the correct answer when one factors the speed of the Sun's movement and overall galactic orbital velocity shows that the only way that our planets can revolve in a flat plane around our Sun with such coincidental momentum is for the Speed of Gravity to be vastly faster than C.
If Gravity was slower, as the Sun head North, the planets' orbits would look like a wedding cake with each rotation being further South as you went outward from the Sun from one planet to another...because there would be a gravitational lag by the time the Sun in its old position affected a planet.