Sun's Magnetic Hole Returns as Solar Storm Tickles Earth

The NOAA issued a solar storm warning at around midday (ET) on Thursday as a coronal mass ejection (CME) made a glancing blow to our planet. At time of writing, the storm was underway, but it ranks as a minor storm, just breaching “S1″ on the Solar Radiation Storm scale. “S5″ is the most extreme classification of solar storm.

The high-energy particles currently buzzing around our planet’s magnetosphere (the global magnetic bubble that deflects these solar ions from penetrating deep into the atmosphere) are only a taster of what’s to come, however.

Solar observatories are currently tracking the same coronal hole that acted as a “fire hose” earlier this month, spraying Earth with a stream of high energy, high-speed solar wind particles. This intense stream of solar plasma triggered some powerful high-altitude aurorae on Oct. 7 and 8, a display that looked most dramatic for the astronauts and cosmonauts on board the International Space Station.

Known as a “coronal hole”, the obvious dark patch in the sun’s magnetic atmosphere (the corona), pictured above, is basically a low density plasma region where “open” magnetic field lines allow plasma to rapidly escape from the sun. Bright, and therefore more dense, regions are populated by “closed” field lines, where plasma remains trapped in the lower corona by magnetic loops that thread from the solar interior and high into the corona.

But now, the same coronal hole has carried out a full rotation of the sun and appears to be in a stable configuration and will likely, once again, spray Earth with solar ions in the first week of November, igniting a similar auroral display as this month.

In addition to this solar drama, according to Spaceweather.com, Earth is currently passing through a fold in the heliospheric current sheet. As the sun rotates, it constantly releases solar wind particles into space. Because it is rotating, these particles stream throughout the solar system in a “spinning lawn sprinkler” pattern. Associated with this particle flow is a current sheet that looks like a spinning warped vinyl record. This sheet represents the boundary where the magnetic polarity switches from “north” to “south”. Passing through the sheet, and therefore passing through an interplanetary polarity change can also trigger geomagnetic storms and increased probabilities of auroral displays.

For the most part, getting hit by CMEs, getting sprayed by the fast solar wind and passing through heliospheric current sheets creates more of an opportunity to see auroral displays -- one of the greatest natural wonders our planet has to offer. But as high-energy solar particles begin interacting with our planet’s magnetosphere, there can be some unpleasant side effects.

Read more at Discovery News