evidence: Associate Professor of Astronomy Douglas Leonard explains why sunspots, solar flares, and space weather events increase in frequency as the Sun's magnetic field flips. Every 11 years the Sun’s magnetic pole flips. Leading up to this event, there is a period of increased solar activity — from sunspots and solar flares to spectacular northern and southern lights. The current solar cycle began in 2019 and scientists predict it will peak sometime in 2024 or 2025 before the Sun returns to a lower level of activity in the early 2030s. [...] Scientists have dubbed this "solar cycle 25". How did scientists determine that the solar cycle is 11 years long?