If earth were the size of a pea (a 1 cm. marrowfat to be specific), the sun would be a one meter diameter freak marrow (giant squash for American readers) 118 meters away. The edge of the solar system would be a further 8 kilometers out and our nearest stellar neighbour, Proxima Centauri, more than 30,000 kilometers beyond - that’s twice the distance from London to Alice Springs. Continuing outward, the near edge of our Milky Way galaxy would be 178 million kilometers, and in the other direction, galactic centre 193 million kilometers. Billions of stars beyond, the far galactic edge would be 564 million kilometers distance from us, if Earth were the size of a pea.
But these distances are as nothing compared to the 350 TRillion kilometers you would need to trek to get to the end (i.e. our observational horizon) even of this miniature universe. Travelling at the speed of light in a swanky futuristic spaceship, it would take you thirty-seven years to get there. Once there, a similar vista of endless stars would greet you and you wouldn’t even realise you had completed your journey. Now, whether you’re impressed by this or not, I feel sure after ten minutes hurtling at light-speed to the ever-receding edge of the mini-verse from a planet the size of a pea, you’d be asking, “Are we nearly there yet?”
Were you to forgo the spaceship, don your best spaceboots and walk , you could be out of the mini -solar system within the hour, no doubt thinking you’re making good progress. The remaing eight billion years (yes, we’re still at the pea-scale) however would leave you wondering whether it was wise to have started. That said, the star-spangled, wondrous views might sustain you, while for amusement you could be squinting through a magnifying glass like Sherlock Holmes at any potentially life-supporting planets on the way.
So the universe is big, and I mean BIG !
There are some 200 billion stars in our galaxy alone and, in the wider universe, a 100 billion galaxies ranging in size from a few billions to trillions of stars. All told there are 20 billion trillion stars throughout the firmament. This reads more impressively as 20,000,000,000,000,000,000,000 stars. If, in a rather foolhardy manner, you thought to represent each star with a bucket of water, well, you just couldn’t -- at least not without calling upon another two hundred earth-like planets, all of which you would need to drain bone dry. Your hardware store would be none too pleased either by your unending demand for buckets. Although I suppose you could get around this by using the same bucket over and over and sneakily tipping the water into a paddling pool. One piece of advice I think is worth giving you, if you’re seriously going to try this, is to find a nice little home by the sea. Oh and you could perhaps ask the locals to hold the fish for you.