For example, dopamine plays a big role in starting movement, and the destruction of dopamine neurons in an area of the brain called the substantia nigra is what produces the symptoms of Parkinsonâs disease. Dopamine also plays an important role as a hormone, inhibiting prolactin to stop the release of breast milk.
Why are sunspots darker than the rest of the Sun? Sunspots appear dark (in visible light) because they are much cooler than the rest of the surface of the Sun. However, even though they appear dark, they are still very hot. Sunspots have temperatures around 6,300 Fahrenheit (~3,500 Celsius) while the surrounding surface of the sun has a temperature of about 10,000 Fahrenheit (5,500 Celsius). If a sunspot was alone in space, it would glow brightly.
Sunspots and Solar Storms. Galileo was the first to study dark spots on the Sun which we call sunspots. They typically measure about 10,000 kilometers across, which makes them on the order of the size of the Earth. They often occur in groups, and come and go. At some times the Sun has hundreds of sunspots, while at other times it may have almost none. Individual spots may last from 1 to 100 days.