Here is how John Cassidy explains the scale of our universe.
He instructs us to find a large open space and place a soccer ball in the center to represent the sun. He then directs us to walk 10 paces in a straight line, stick a common pin in the ground. The head of the pin stands for the planet Mercury. Then take another 9 paces beyond Mercury and put down a peppercorn to represent Venus. Step 7 more paces and drop another peppercorn for Earth. One inch away from Earth, another pinhead represents the Moon. Take 14 more paces and place a peppercorn for Mars, then 95 paces to Jupiter, and place a ping-pong ball. Take 112 paces further and place a marble to represent Saturn.He then inquires, “How far would you have to walk to reach the nearest star, Proxima Centauri?” He instructs you to pick up another soccer ball to represent it and set off for a walk of 4,200 miles. As for the nearest other galaxy, Andromeda, he suggests, don’t even consider it!