Today I got an email from ma girl Amanda* asking about the “Sun burp” over Norway. Well, cool. This is actually something I know something about.
Here’s what’s going on. Solar flares are charged particles shot out of the Sun. Generally these particles are confined to the Sun itself (although much of the corona of the Sun is mini-ish-solar flares) — you can think of them flowing around the surface of the Sun along its magnetic field lines (I think of the magnetic field lines like rubber bands wrapping and twisting around the Sun — there are problems with this, of course, but it works alright for this purpose). Solar flares, at least little ones, happen quite often, but scientist have found that about every eleven years there is an increase of solar activity (apparently we’ve been in quite a lull for a while, but things might be heatin’ up!).
Although this isn’t well understood, scientists are pretty sure that it has something to do with magnetic fields (due to the correspondence of sunspots and solar flares). There’s one theory that goes like this: the Sun’s magnetic field lines get so twisted and twirled that they reach the peak of what they can handle about every eleven years — then they go ‘snap!’ and, like a when you pull a rubber band and it breaks, the loose ends lash out. And, well, charged particles curl around and flow down magnetic field lines, so if a magnetic field line is extending out of the Sun, then charged particles will flow along and out of the Sun. I’m explaining this in a slow-motion type way, however this happens pretty fast (although, granted, the timescale is minutes or tens of minutes — not, you know, femtoseconds). In fact, this is downright violent:
The amount of energy released is the equivalent of millions of 100-megaton hydrogen bombs exploding at the same time!
(from NASA’s solar people.) The magnetic field lines quickly right themselves along the Sun.
But what we get from this process is a solar flare (sometimes huge, every now and then directed at us). When charged particles come at us, the Earth, we’re thankfully protected by magnetic field shield of our own (due to the Earth’s rotating metal core). These charged particles hit the Earth’s magnetic field and are filtered along them to the magnetic North pole and South pole. Once there, those particles filter down and interact with the atmosphere to create beautiful aurorae (Borealis for the north and Australis for the south).
The stronger the solar flare, the more the charged particles, the brighter the aurorae and therefore the further towards the equator these aurorae can be seen. It’s being predicted that for the particular solar storm we’re currently experiencing — who knows?! — we may even be able to see then down in DC! (Honestly, if we could see it down here, it wouldn’t be very clear. Although you could try staring really hard. See what happens. I dare you.)
I think this really cool.
Note: a similar physical process is happening within particle accelerators! That’s why they got those superconducting magnets in ’em — to create the magnetic fields that guide the charge particles.
More info and some articles:
(1) NASA’s RHESSI website. The place to go for solar flare information.
(1b) NASA SOHO website. Where you can find some incredibly cool images and videos.
(2) “NASA Scientists Braced for ‘Solar Tsunami’ to Hit Earth.” Telegraph article from 8/2/2010 about our imminent destruction (and the motivation for this post). Also, pretty skies…mmmmsensationalism. Tasty.
(3) More about the eleven year solar activity cycle here.
(4) I really like this website from Montana State University about solar magnetic fields, and the like.
*Amanda T. you rock, as always.