Aurorae occur during geomagnetic storms, which are triggered by eruptions on the Sun. A large, active region has produced several strong flares recently. The solar wind, a fast-moving stream of particles constantly moving from our star, carries the Sun's magnetic field into space. The wind, typically flowing at 250 miles (400 kilometers) per second, can mingle with Earth's magnetic field, generating electrical currents that force protons and electrons into the polar atmospheres. Collisions between these particles and atmospheric gases illuminate the polar ovals, typically between heights of 62 and 155 miles (100 to 250 kilometers).
Using the Transition Region and Coronal Explorer (TRACE) satellite, Cirtain's team witnessed unusual energetic activity in this sunspot region. "In one case, we recorded 5 separate flares over the course of 6 hours. That's very unusual."
This activity could continue — the National Oceanic and Atmospheric Administration predicts a 75-percent chance of additional X-class flares within the next day.
When this activity appeared in August with Region 10798, 798 for short, eruptions caused a few auroral displays on Earth. The area disappeared from sight as the Sun revolved. Late last week, the sunspot recurred, giving hope to aurora aficionados. (When an active sunspot reappears after one revolution, it receives a new numeral designation.)
To view the potential aurorae, keep your eyes fixed north from your favorite dark-sky location.
For future aurora predictions, visit our space weather section
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