What does 10 years mean to our 4.6 billion-year-old sun? Probably about as much as the last millionth of a second meant to you. Yet every decade our old sun burns is a decade of turbulent, sometimes violent change – a fact that becomes beautifully visible in a new video from the time lag of NASA’s Solar Dynamics Observatory (SDO).
In a stunning video titled “Decade of the Sun”, astronomers compiled 425 million high-resolution solar images, taken once in 0.75 seconds between June 2, 2010 and June 1, 2020. Every second of the video represents one day in solar life and an entire decade flashes for about 60 minutes (although you can see the 1-minute video above).
During that decade, the sun undergoes a sea change, slowly bubbling with huge magnetic waves known as sunspots, which peaked around 2014 before fading again. The sun’s silence was no surprise; every 11 years or more, the sun’s magnetic poles abruptly switch places; North becomes South, solar magnetic activity begins to decline, and the solar surface begins to look like a calm sea of yellow fire. This period of relative calm is called the solar minimum (and we are currently in the middle of one).
Halfway between the turning points of one decade and another, a violent shift follows. Magnetic activity increases to a vibrant maximum, known as the solar maximum, and the star on the surface crawls with giant sunspots, bristles with magnetic lines of the magnetic field, and plasma explosions called solar explosions. Each maximum peak, with a different reversal of the magnetic pole, signals the beginning of a new solar cycle.
These changes from Earth are hard to see with the naked eye (although solar maxims lead to a more visible aura in the lower latitudes of the world), but NASA’s SDO satellite clearly sees them as it tracks our star in extreme ultraviolet light. These ultra-energy wavelengths penetrate the sun’s reflection and reveal abundant magnetic changes in the Sun’s farthest atmosphere or in the corona. A stunning spectacle to see – even if the sun has probably already forgotten everything about it.