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Tags Current Affairs

Sun enters new cycle

Date: 10 December 2020 Tags: Space

Issue

Scientists have suggested that our Sun has reached its next maximum in activity cycle, which could be one of the strongest we have seen.

 

Background

This observation is in direct contradiction to the official solar weather forecast from NASA, but if it sustains, it could confirm a theory about solar activity cycles that scientists have been working on for years.

 

Details

  • Scientists have struggled to predict both the length and the strength of sunspot cycles because of lack a fundamental understanding of the mechanism that drives the cycle.

  • The Sun's activity levels are actually variable, and its activity cycles are bound up with its magnetic field.

  • Every 11 years, the Sun's poles swap places; south becomes north and north becomes south. It's not clear what drives these cycles, but we know that the poles switch when the magnetic field is at its weakest.

  • Since Sun's magnetic field controls its activity such as sunspots (temporary regions of strong magnetic fields), solar flares, and coronal mass ejections (produced by magnetic field lines snapping and reconnecting), this stage of the cycle is as a period of very minimal activity. It's called the solar minimum.

  • Once the poles have switched, the magnetic field strengthens, and solar activity rises to a solar maximum before subsiding for the next polar switch.

  • The most recent solar minimum took place in December 2019. We're now in the 25th solar cycle since record-keeping began, headed into a solar maximum.

  • This is expected to be a quiet maximum, with a sunspot peak of around 115 sunspots in July 2025. This is pretty similar to Solar Cycle 24, which had a sunspot peak of 114.

 

Sunspots

  • Sunspots are temporary phenomena on the Sun's photosphere that appear as spots darker than the surrounding areas.

  • They are regions of reduced surface temperature caused by concentrations of magnetic field flux that inhibit convection. Sunspots usually appear in pairs of opposite magnetic polarity.

  • A typical spot consists of a dark region called the umbra, surrounded by a lighter region known as the penumbra.  

  • The sunspots appear relatively dark because the surrounding surface of the Sun (the photosphere) is about 10,000 degrees F., while the umbra is about 6,300 deg F.  Sunspots are quite large as an average size is about the same size as the Earth.

 

Solar flares and its effects

  • Coronal Mass Ejections and solar flares are extremely large explosions on the photosphere.  They occur near sunspots, usually at the dividing line between areas of oppositely directed magnetic fields. 

  • Hot matter called plasma interacts with the magnetic field sending a burst of plasma up and away from the Sun in the form of a flare. 

  • Solar flares emit x-rays and magnetic fields which bombard the Earth as geomagnetic storms.  If sunspots are active, more solar flares will result creating an increase in geomagnetic storm activity for Earth. 

  • Therefore during sunspot maximums, the Earth will see an increase in the Northern and Southern Lights and a possible disruption in radio transmissions and power grids. 

  • The storms can even change polarity in satellites which can damage sophisticated electronics. 

  • Therefore scientists will often preposition satellites to a different orientation to protect them from increased solar radiation when a strong solar flare or coronal mass ejection has occurred.

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