Does anyone know the Isaac Asimov book where he scales the universe?

[A P]

I remember reading an incredible Isaac Asimov article where he attempts to put the scale of the universe into a human perspective such that we can better appreciate it. He started by suggesting if the Sun was the size of a water melon, the Earth would be a cherry, Mars a pea and Jupiter a plum about 100 metres away (my memory of the details may be somewhat vague). Asimov soon ran out of space on Earth to contain even our Milky Way galaxy and had to change scales. In order to contain the universe in a human perspective, he eventually settled on a scale factor of a typical star being of molecular size, and the universe then shrank to become a small wispy hardly discernible cloud of gas. I would love to obtain this book which is full of incredible facts as only Asimov can portray them to his dear readers, so if anyone knows its title 10 points await you.