Slide 1
Sunspots look dark because their surroundings are brighter
Sunspots are regions of the Sun’s visible surface that are cooler than their surroundings. They look dark because nearby material emits more light.
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Dark is a comparison in this setting, not an absence of radiation. Removed from the bright solar background, a sunspot’s material would still emit intense light because of its high temperature.
Slide 2
Magnetic fields reduce the usual heat transport
Concentrated magnetic fields inhibit the usual flow of hot plasma in sunspot regions. Reduced energy transport helps keep those regions cooler.
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The field and moving plasma influence one another. A sunspot therefore belongs to a dynamic magnetic structure rather than behaving like a stain attached to a rigid surface.
Slide 3
Spot counts vary through a roughly eleven-year cycle
The number of sunspots varies through the solar activity cycle. The interval between minima is roughly eleven years, with variation between cycles.
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The Sun’s global magnetic polarity reverses during a cycle, so returning to the same polarity takes about two cycles. A cycle in spot counts and a full magnetic cycle are related but not identical measures.
Slide 4
Different solar latitudes rotate at different rates
Different solar latitudes rotate at different rates. This differential rotation is part of the Sun’s changing magnetic behavior.
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Tracking spots helped reveal the rotation, but individual spots also grow, change and disappear. A feature can serve as a tracer while still having its own lifetime and evolution.
Slide 5
Spot counts track activity without predicting each eruption
Sunspot-rich periods are associated with greater solar activity. A spot count alone does not specify the time or impact of a particular eruption.
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Space-weather assessment combines magnetic observations, eruptions and particle measurements. The connection to Earth also depends on where an event occurs and whether its effects travel toward our planet.
Sources
- Sunspots
NASA
- The Solar Cycle
OpenStax, Rice University
- Space Weather
NOAA Space Weather Prediction Center