Sun Science!

Ok, legitimate post! Yay break!

Today I present the only part of astronomy that I've followed religiously through my humanities phase: space weather!

What is space weather? It's the interactions between the Sun (and what it throws off) and the Earth (or other planets, but we're egocentric). Aurorae are the most famous visual manifestation of space weather, but there's a lot more to it. To understand the phenomena, we should start with a basic understanding of the composition of the Sun and our little home rock...

The Sun: this site (click here) gives a good, if slightly technical, description of the Sun's layers. As an overview, the Sun is essentially one vast ball of hydrogen gas (~91% H atoms), which is so immensely large that the hydrogen in the core gets crushed under its own "weight" into helium via nuclear fusion.* However, it's also got layers, like the Earth does. There's a large convective layer that mixes the extremely hot gas around the Sun's interior, and this creates electromagnetic currents. These currents run like strands through certain localities; they are not consistent throughout the Sun -- remember this, it's is important later. The outermost layer spins like a skin on a spherical pudding (insert typical physicist joke on spherical objects here). Much like the Earth's crust, it spins at a different speed from the lower layers; however, unlike the Earth's crust, the section near the equator spins once every 25 days, while the poles rotate once every 36 days. This causes something like friction at the regions where the speeds differ.

I'll carry on with the Earth next time; that's right, I'm leaving you with a cliff-hanger! 'Til next time, redshifted readers! And merry Christmas!


*N.B.: I put weight in quotes here, because weight and mass aren't the same thing. To use the age-old example, you weigh about 1/6 of your normal Earth weight on the Moon, but you certainly haven't shrunk -- in other words, your weight has changed but your mass hasn't. This is a function of the mass of the object you're standing on (or in, in the case of the hydrogen atoms in the Sun). In space, this becomes important, since gravity has a different magnitude for every star, planet, etc.