Best way for us to visualize size,and speed of motion. Here is a good
illustration. It takes 11 Earth's to equal the size of Jupiter.Jupiter
has a period of rotation of 10 "Earth hours". Rather than say the Sun is
93 million miles away we should say you can fit 97 Suns between it and
Earth. The moon is 30 Earth's away. I like quasars being the size of
our solar system. It is very hard to think we can tell 10 LY from 20 LY
in our minds eye. I like knowing a photon can circle the Earth 7 times
in one second. I like seeing I can stop a ray of light an inch and a
half from its source. To say a gamma explosion took place 7.3 billion
LY from us only means to me it happened "once upon a time" and very far
away. Bert