Here's how we know it spins:
* Sunspots: Sunspots are darker areas on the Sun's surface. They appear and disappear over time, and their movement across the Sun's surface tells us about its rotation.
* Doppler Effect: The Doppler effect causes light from the Sun to be shifted slightly depending on whether it's moving towards us or away from us. We see this shift differently depending on which part of the Sun we're observing, indicating its rotation.
The Sun spins differentially, meaning different parts of it rotate at different speeds. Its equator rotates faster than its poles. It takes about 25 days for the Sun to complete one rotation at its equator, but about 36 days at its poles.
