Our house. Imagine we scale down the Milky Way, making it 400 trillion times smaller until it’s the size of the United States, and we lay it out flat across the US. Now about 5,000 km or 3,000 miles across, it would take you two months to walk across our miniature Milky Way if you walked every waking hour of every day. If you were walking around, looking for stars, you wouldn’t actually see very much. The very biggest stars would be about the size of a pea. Our Sun would be so small, its diameter 1/20 of a human hair, you’d need to use a microscope to see it. And stars would be few and far between. If you were standing on our Sun, the closest star would be a football field away. Only from far away do galaxies look like busy places. When you’re inside of one, it’s almost all emptiness.
For a long time, astronomers estimated that the Milky Way stretched about 100,000 light years across, but that estimate has about doubled in recent years, and it may still be a work in progress.
Keishinrei 