Spiral arms and stellar motion
Spiral arms are wave density, through which stars travel, similar to traffic jams on a road.
🌟 200-400 billion stars
📏 100 000 light-years in diameter
🔄 230 million years — one rotation
☀️ The Sun is 26,000 light-years away from the center
Stars at the edges of the galaxy move faster than expected. This indicates the presence of dark matter!