A sunspot is a dark patch on the surface of the Sun that appears darker because it's cooler than the surrounding area. These spots can be enormous: some are larger than Earth itself. Through special telescopes (never look directly at the Sun!), sunspots appear as dark blotches against the Sun's bright surface.

Sunspots form where powerful magnetic fields push through the Sun's surface, blocking some of the heat from below. They're not actually cold: a sunspot might be around 6,500 degrees Fahrenheit, while the rest of the Sun's surface blazes at 10,000 degrees. That 3,500-degree difference makes them look dark by comparison, like how a flashlight beam seems dim in bright sunlight but brilliant in a dark room.

Scientists track sunspots carefully because they reveal the Sun's activity level. The Sun goes through an 11-year cycle: sometimes it has many sunspots and becomes more active, sending powerful bursts of energy into space. Other times it has few sunspots and stays calmer. These solar storms can affect satellites, radio communications, and even power grids on Earth.