Right now, the Sun is sporting a huge sunspot called AR1944. Itâs grown in size over the past few days to a staggering 200,000 kilometers (125,000 miles) across. As I wrote the other day, sunspots are regions of intense magnetism, and these magnetic fields store huge energies. They can be unleashed in vast explosions called solar flares â¦ and AR1944 popped off a good one on Jan. 7. The image above shows the Sun in ultraviolet by NASAâs Solar Dynamics Observatory, taken on Jan. 7 at 18:33 UTC, just after the flare exploded. The bright white patch? Yeah, thatâs it.
The flare was a class X1, which is pretty strong. It also triggered a coronal mass ejection, an eruption of subatomic particles, toward the Earth. Thereâs no need to panic; these happen relatively often. This one was pretty fast, with a speed of about 2,000 kilometers per secondâthatâs 4.5 million miles per hour!
Itâs expected to hit the Earthâs magnetic field sometime today or tonight. The Space Weather Prediction Center says it may interact strongly with our geomagnetic field, producing aurorae. Iâve seen some folks predicting even mid-latitudes may see the lights, so I urge folks to go out after dark and look north. Unfortunately the Moon is half-full and so the sky will be a bit bright. It sets just after midnight local time, so if you go out later your chances of seeing the aurora might be better. It looks like weâll have clear skies here in Boulder, Colo., so Iâll be taking a peek. Aurorae may still be visible Thursday night as well.
Iâll note that this storm provoked the delay of an Orbital Sciences Corporation launch of their Antares rocket, scheduled to lift off today on a resupply mission to the International Space Station. The increased radiation levels could screw up the systems onboard, so they decided to postpone. Follow Orbital on Twitter for up-to-date info on that.