1. Sunspots
Sunspots are black spots on the surface of the Sun. They were first seen thousands of years ago by Chinese and Indian astronomers. Greek observers referenced them in 400 B.C. In western history, Galileo first observed them through a telescope and diagramed their movement in 1610.

2. When Galileo first recorded these “blemishes” on the Sun, it was a shock to the social and religious communities, because things in the sky were thought to be divine and perfect.

3. The Sun has a strong magnetic field, that acts like a bar magnet with a “north” and “south” pole, just like the Earth.

4. The Sun is made of gas, not a solid like the Earth
The Sun is made of gas, not a solid like the Earth. It rotates at different speeds at different latitudes, the equator rotates faster than the poles. The whole magnetic field gets twisted up over a period of years.

5. As the magnetic field gets more and more twisted, sunspots form where invisible magnetic field lines break through the surface, then go back into the Sun.

6. Sunspots appear black because they are cooler than the surrounding Sun
Sunspots appear black because they are cooler than the surrounding Sun. The strong magnetic field traps the hot gases of the Sun and slows them down, cooling off the sunspot to about 4000 K from 6000 K.

7. The Sun goes through a regular cycle of its magnetic field getting all wrapped up, and then flipping back to normal. Over a period of years, you will see times when there are a lot of sunspots, and times when there are almost none.