I just finished reading Carl Sagan’s Pale Blue Dot, and doing so made the astronomer in me appreciate the vast and unknown universe that makes up 99.99999% of existence. Luckily, there are plenty of amazing people who devote their entire lives to this cause, such as the folks at the Swedish Solar Telescope. In 2002, this telescope (located in La Palma, Spain) collected a remarkable high-res image of a sunspot the size of a planet.
Seen above as the dark core that is surrounded by the white hot filaments, one might think a sunspot is an actual hole in the Sun’s exterior. Actually, it’s made of the same gas that exists everywhere else in the Sun, so why do they look so different? The answer lies in magnetism.
Like They Might Be Giants said, “The sun is a mass of incandescent gas.” It consists of a gas of protons fusing to make helium nuclei at a very high temperature (around 6000 K). This process occurs at the sun’s core, and as these gases make their way outwards towards the surface, it creates a turbulent and chaotic environment.
As the sea of gas moves around on the Sun’s surface, it creates an incredibly powerful magnetic field. Pockets of magnetic pressure are formed that allows the gas within to cool down, resulting in the dark holes that we know as sunspots. (By cool, I mean not quite as earth-shatteringly hot… it’s still around 4000 K!) While sunspots themselves do not affect the earth, the magnetic fields that create them certainly do.
Rather than go into the details (I’m just a neuroscientist, after all), I’ll appeal to this slightly frightening picture. The lines emanating from the Sun represent its magnetic field, and those around the earth represent our “magnetosphere,” a strong magnetic field created by the earth that protects us from all the magnetic activity the Sun routinely throws our way.So next time you’re looking at the little ball of yellow in the sky, think about all the chaos happening on its surface. Think about the massive oceans of gas that are powerful enough to affect us on here on Earth millions of miles away, and then you can pick your jaw up off of the floor.
The Exploratorium’s guide to sunspots