The Physics of the Northern Lights

But wait! The helium nucleus has little wide than the 4 protons we started with. That wide isn’t lost—it’s turned into energy, according to Einstein’s celebrated equation E = mc², wherever E is energy, m is mass, and c is the velocity of light. That past fig is huge—light travels astatine 300,000 kilometers per second, and it’s hugeness is squared—which means that adjacent a tiny nonaccomplishment of wide creates A LOT of energy. That’s wherefore the prima is truthful hot, with a halfway somesthesia of 27 cardinal degrees Fahrenheit. Yep, that’s beauteous hot.

Under this utmost heat, the gases successful the outer portion of the prima signifier a plasma successful which electrons are ripped distant from their atoms, leaving escaped electrical charges (mostly electrons and protons) zooming around. Some of them are moving accelerated capable to flight the gravitational propulsion of the sun. These ejected particles are what we telephone the “solar wind.”

You tin spot the effect of the star upwind erstwhile it hits a comet. Comets are fundamentally large soiled snowballs that orbit the prima successful agelong ellipses. As 1 nears the sun, its icy assemblage sublimates and turns into a gas. Some of this state gains capable vigor to beryllium ionized (electrons are freed from the atoms), leaving an electrically charged gas. Then, erstwhile the star upwind hits, it pushes this ionized state away, creating a process that tin beryllium tens of millions of miles long.

Fun fact: You mightiness deliberation the process extends retired down the comet similar a pitchy contrail, but it doesn’t! It extends distant from the sun—so fundamentally sideways to the absorption of the comet’s motion.

Why Now?

But what causes the star upwind to get truthful worked up each 11 years? Well, similar Earth, the prima has a magnetic field, but it’s highly unstable. Because the prima is not a coagulated object, antithetic parts of it rotate astatine antithetic speeds. This causes its magnetic tract to twist and warp, and each 11 years oregon truthful it really flips and reverses polarity. This past happened successful 2013, and present we are now.

These moving magnetic tract lines tin interruption done the surface, creating prima spots and awesome geysers of plasma known arsenic star flares. Why does this happen? When electrical charges are zipping around, they tin beryllium pushed and pulled by a magnetic field. You tin spot this yourself with immoderate copper ligament and a battery. If you spot the ligament adjacent a stationary magnet and past link the ends truthful a existent flows, the ligament volition move. Check it out: