Our Milky Way Galaxy: How Big is Space? - NASA Science

if the Milky Way Galaxy were scaled down to the size of North America (roughly 4,500–5,000 km across), the Sun would be approximately 6 micrometers in diameter, which is roughly the size of a red blood cell. This comparison highlights the immense, mostly empty space between stars in our galaxy. The Milky Way is about 10^21 meters wide, while the continental USA is roughly 5 x 10^6meters, creating a reduction factor of approximately 200 trillion to 1. The Sun's actual diameter of 1.39 million km

Milky Way Facts: Lesson for Kids