The aurora borealis is often seen solely means up north, however two weeks in the past the night time sky was stuffed with shimmering curtains of pink and inexperienced mild that could possibly be seen all the best way down into the southern US. People in Texas and Hawaii received out of their vehicles to stare and take photos.
The reason for this mild present was an particularly robust blast of photo voltaic wind—electrically charged particles shot out from the solar at unbelievable speeds. And there’s extra to come back as we method the height of the present photo voltaic cycle, a interval of elevated photo voltaic storms that occurs each 11 years.
This is one instance of what scientists name “space weather,” which offers with the interplay between the solar and the Earth. Not all the results of house climate are fairly, and a few are outright harmful. But the physics behind it are fairly cool. Let’s test it out!
Blowin’ within the Wind
You may consider the solar as a terrific ball of fireside—however it’s not. (Fire is a chemical response between oxygen and carbon.) What the solar is, actually, is a huge nuclear fusion reactor. In the core, protons are smashed collectively beneath excessive stress. These protons stick collectively to create the nucleus of a helium atom, with two protons and two neutrons. (Two of the protons decay into neutrons).
Illustration: Rhett Allain
But wait! The helium nucleus has much less mass than the 4 protons we began with. That mass is not misplaced—it is become power, in response to Einstein’s well-known equation E = mc2, the place E is power, m is mass, and c is the velocity of sunshine. That final quantity is big—mild travels at 300,000 kilometers per second, and it is hugeness is squared—which signifies that even a tiny lack of mass creates A LOT of power. That’s why the solar is so scorching, with a core temperature of 27 million levels Fahrenheit. Yep, that is fairly scorching.
Under this excessive warmth, the gases within the outer a part of the solar type a plasma by which electrons are ripped away from their atoms, leaving free electrical costs (principally electrons and protons) zooming round. Some of them are shifting quick sufficient to flee the gravitational pull of the solar. These ejected particles are what we name the “solar wind.”
You can see the impact of the photo voltaic wind when it hits a comet. Comets are principally large soiled snowballs that orbit the solar in lengthy ellipses. As one nears the solar, its icy physique sublimates and turns right into a gasoline. Some of this gasoline beneficial properties sufficient power to be ionized (electrons are free of the atoms), leaving an electrically charged gasoline. Then, when the photo voltaic wind hits, it pushes this ionized gasoline away, making a tail that may be tens of hundreds of thousands of miles lengthy.
Fun truth: You may suppose the tail extends out behind the comet like a jet contrail, however it does not! It extends away from the solar—so principally sideways to the course of the comet’s movement.
Why Now?
But what causes the photo voltaic wind to get so labored up each 11 years? Well, like Earth, the solar has a magnetic area, however it’s extraordinarily unstable. Because the solar will not be a strong object, totally different elements of it rotate at totally different speeds. This causes its magnetic area to twist and warp, and each 11 years or so it truly flips and reverses polarity. This final occurred in 2013, and right here we’re in 2024.
These shifting magnetic area strains can break via the floor, creating solar spots and superior geysers of plasma often known as photo voltaic flares. Why does this occur? When electrical costs are zipping round, they are often pushed and pulled by a magnetic area. You can see this your self with some copper wire and a battery. If you place the wire close to a stationary magnet after which join the ends so a present flows, the wire will transfer. Check it out: