Sunspots come and go in 11-year cycles with fluctuations in solar magnetic activity
The sun is our nearest star. Now that the spring equinox has passed, back on 20 March, it will increasingly dominate the sky in the northern hemisphere. Days will get longer, and nights shorter until summer finally arrives. The sun’s bright surface usually displays transitory dark blemishes known as sunspots. Every 11 years or so, the sunspots become much rarer. Between 2011 and 2015, there were only 3 sunspot-free days. In 2017, 104 days were free. Already this year, spots have been absent for more than 50 days. This clearly shows we are heading for solar minimum, expected to arrive next year. Sunspots are produced by solar magnetic activity. This is the same force that creates space weather, which can short-circuit spacecraft and interfere with communications and power lines on Earth. Never look directly at the sun through any optical instrument or with the naked eye. The fearsome light can cause permanent blindness.