Mains Paper 1: Geography | Salient features of World’s Physical Geography
From UPSC perspective, the following things are important:
Prelims level: Sunspots, Solar Tsunami
Mains level: Impact of Sunspots on mankind as a whole
- A group of solar physicists suggests that a “solar tsunami” is at work that triggers the new sunspot cycle, after the old one ends.
- It is believed that the “solar dynamo” a naturally occurring generator which produces electric and magnetic fields in the sun is linked to the production of sunspots.
- What kick-starts the 11-year sunspot cycle is not known.
- The extreme temperature and pressure conditions that prevail some 20,000 km below the sun’s surface cause its material to form plasma consisting primarily of hydrogen and helium in a highly ionised state.
- The plasma is confined with huge magnetic fields inside the sun.
What is Solar Tsunami?
- The sun’s magnetic field, from which sunspots get generated, wraps around the sun in the east-west direction.
- These magnetic fields behave like rubber bands on a polished sphere. They tend to slip towards the poles.
- Holding these fields in their place requires that there is extra mass (plasma mass) pushing at the bands from higher latitudes.
- Thus, a magnetic dam is formed which is storing a big mass of plasma.
- At the end of a solar cycle, this magnetic dam can break, releasing huge amounts of plasma cascading like a tsunami towards the poles.
- These tsunami waves travel at high speeds of about 1,000 km per hour carrying excess plasma to the mid-latitudes.
- There they give rise to magnetic flux eruptions.
- These are seen as the bright patches that signal the start of the next cycle of sunspots.
What are 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.
Why study them?
- The solar cycle and sunspot activity are intimately connected with space weather.
- The model provides a sound physical mechanism supporting why we should expect the next sunspot cycle 25 to begin in the year 2020.
- This is again followed by a strong increase in space weather shortly after the trigger of a series of new sunspots in that year.