A polarity-reversed sunspot has unleashed a solar flare that is expected to trigger a moderate to strong geomagnetic storm on Earth either tonight or tomorrow. People in the right locations can get another similar treat of the Northern Lights in late February and March 23. For those with proper reasoning, there will also be the intellectual thrill of knowing that what they are seeing comes from a rare class of sunspots.
On Sunday evening UTC, a M1.5 solar flare It has been reported By Spaceweather.com. By Monday morning US time, the Space Weather Watch was declaring Associated coronal mass ejection (CME). Both flares and the CME, which often occur together, can lead to geomagnetic storms when high-energy photons or charged particles encounter Earth’s upper atmosphere.
However, at first glance, this event may not seem like an event that would cause much excitement. Class M is the second largest class of flares, after X, and with a scale up to M10, 1.5 is pretty modest. Three years ago, in the depths of the solar calm, this would have been big news, but the past few months have seen flares more than 10 times larger.
However, although it never reached this magnitude, the flare was unusually long, lasting six hours. Most importantly, the CME appears to be heading straight for Earth. A direct hit from a small CME can cause more auroral activity than a glancing blow from something larger.
However, knowing that the CME will likely hit Earth’s magnetosphere, and knowing when it will happen are two different things. This aurora is estimated to be flowing toward Earth at between 700 and 1,100 kilometers per second (1.6 million – 2.5 million miles per hour). With a distance of 150 million kilometers (93 million miles) to be covered, the difference between the top and bottom of that range leads to a gap in arrival time of more than a day. If the resulting aurora only lasted a few hours, that would mark the parts of the planet that have aurorae during daylight when no one can see them.
National Oceanic and Atmospheric Administration Twilight dashboard Moderate storm activity is currently expected from 11 p.m. to 3 a.m. Wednesday evening/Thursday morning UTC. “With a chance of isolated G2 (moderate) storms and a slim chance of G3 (strong),” this would provide ideal viewing times in North America, but predictions for events like this still carry a lot of uncertainty.
Should the aurora borealis occur, observers will have something special to add to memory. All sunspots contain dipole magnetic fields. Back in 1909, George Hill noticed that sunspots in the Earth’s hemisphere usually had the same polarity – at that time those in the Northern Hemisphere were all ahead of the North Pole and behind the South Pole, while the opposite was true in the Southern Hemisphere. At the end of the 11-year sunspot cycle, the poles switched between the two hemispheres, and it has done so between every cycle since.
A small minority (about 3 percent) of sunspots exhibit reverse polarity, with their fields in the opposite direction from others in the hemisphere. Some observers claim that these Hale’s Law violators are usually young and weak, but others are skeptical. The sunspot region known as AR3296 is certainly large and powerful. Its negative polarity is on the right in standard orientation images from Earth, in contrast to all around it. Reversed-polarity sunspots often develop entangled magnetic fields, increasing the chance of explosions like the one heading our way.
