March 9: The first detection of Sunspot

Sunspots are dark areas on the surface of the Sun. The surface brightness of dark spots is about 1/4 of the brightness of the surrounding areas (this brightness is very dangerous to the human eye).

The cause of the black spot is because their temperature is lower than the surrounding areas (the stain temperature is about 4000 to 5000 K, according to Stefan-Boltzmann's law , while the surrounding area is about 6000 K), one is The phenomenon is caused by very strong magnetic changes on the Sun. During the development process, the magnetic field of the black spot also gradually increases.

The period of occurrence of dark spots is approximately 11 years.

Black streaks often appear in groups especially in double-group, magnetic fields of the often different polar groups. The largest black spots, the diameter is about 104 km, exists about 2 months, while most of the black spots that exist only a few days later are replaced by other black spots.

The distribution of sunspots is mainly concentrated in the range of 8 degrees to 35 degrees on both sides of the equator of the Sun.

The strong active region with 9393 numbers captured by the MDI on SOHO satellites shows large groups of black spots.On March 30, 2001, the area of ​​these black spots spreads 13 times the surface of the Earth.They were the source of many fire rolls, including the largest fire coil ever seen in the previous 25 years, launched on April 2, 2001. The strong magnetic field was located deep beneath the black mark, making them cooler than the others. neighborhood, and therefore look darker.

Dutch astronomer Johannes Fabricius while observing the Sun through his telescope unknowingly discovered dark spots on the star's surface. This is also the first time an astronomer has observed black marks on the surface of the Sun. However, in 1611, scientists still did not understand the cause and nature of these dark spots. It was not until later that scientists learned that dark spots were high-energy activity on the surface of the Sun and were the cause of the solar storm .