Much like an onion (or our own planet), the sun has an internal structure not visible from the outside. On the exterior is the photosphere--that’s what we can see. This layer reaches 6,000 degrees Kelvin.. Below that is the convective zone, where heat circulates slowly, rising form the inner Sun to the surface and columns of cooled material make their way back down.. Below that is the radiative zone, where heat can only travel via radiation. Temperatures in the radiative zone can reach 13.6 million degrees Kelvin--that’s about 27 million degrees Fahrenheit.
That’s right, the atmosphere surrounding the surface of the sun has way higher temperatures than the surface. The chromosphere--the part of the atmosphere right above the surface--temperatures can reach 100,000 Kelvin. Further out, in the corona, temps can reach upwards of 1 million degrees Kelvin.
That’s right. The outer reaches of the Sun’s atmosphere stretch to a volume greater than that of the sun itself--much like the outer atmosphere is hotter than the surface.
The sun holds 99.86% of the mass of our solar system (fun fact: most of the rest is held by Jupiter). For a bit of perspective, try to picture this: 109 Earths could fit on the surface, and over 1 million Earths could fit inside of it. As an illustration, consider: if the Earth were the size of a marble 1cm in diameter, the Sun would be abou 1.1 meters in diameter--the size of a large blow-up ball, like the kind you’d use in gym class.
Compared to other stars, the Sun is quite small in comparison to others. There are many stars in the universe that are a good deal bigger--up to 700 times the size of our sun. Sirius, for example, the brightest star in the night sky, is twice the mass. Pollux is even larger, with eight times the radius of the sun. In fact, the Sun is classified a a G2dwarf star, which puts it at a soundly average size.
Approximately every 11 years, the sun’s magnetic poles reverse their polarity. Magnetic north becomes magnetic south, and vice versa. Sound crazy? Sure, especially compared to Earth’s relatively stable magnetic poles. But considering the sun is a giant ball of constantly shifting gas and plasma, it shouldn’t be too surprising.
The reason for the shift is connected to this follow-up fact: every 11 years or so, solar activity peaks in a time known as ‘solar maximum’. The sunspots that have been building up on the surface from the previous eleven years explode, sending clouds of gas known as “CMEs” jutting out into the solar system.
Or at least, parts of it do. The sun is comprised of 74%hydrogen and 24% helium (the remaining 2% contains trace amounts of elements like iron, nickel, and oxygen). Since it’s little more than a spinning ball of gas, some parts rotate faster than others. By tracking the movement of sunspots, scientists found that equatorial regions take approximately 25 days to finish a single rotation, while sunspots at the poles can take 36 days to complete a rotation.
...in a while. Remember how the Sun is currently made of of both hydrogenand helium? Scientists estimate that in another 5 billion years or so, it will consume all the hydrogen stored in its core, at which point helium will become the primary fuel.
And no, we’re actually not talking about skin cancer here. The sun is slowly heating up, and becomes 10% more luminous every billion years. Predictions estimate that in less than another billion years, the sun will be so hot that that life as we know it will be unable to exist on earth.
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