Context:

Amidst claims that the Sun would “go silent” and not give out sunspots for an extended period, a group from IISER Kolkata has shown that the next sunspot cycle has begun.

More about the news:Start of cycle 25 :-

• Contradictory to earlier predictions: There has been a lot of controversy about solar cycle 25 stemming from observations of a weakening trend in solar activity over the past three sunspot cycles.  Following a weakening trend in activity over the last few cycles, there were predictions that the Sun would go silent into a grand minimum in activity, with the disappearance of cycles.  However, a team from IISER Kolkata has shown that there are signs that cycle 25 has just begun. 
• Finding of the data:Team from IISER Kolkata used the data from the instrument Helioseismic and Magnetic Imager aboard NASA’s space-based Solar Dynamics Observatory for their calculations.

Significance of the new finding:

• Cooling of the global climate?:Some groups have claimed that this would give rise to a mini ice age and cooling of global climate.
• These findings indicate that sunspot cycle 25 fields have already started appearing, implying that we are going to have a solar cycle. Speculation and predictions of a grand minimum are unfounded.
• Correlation of Sunspot activity with climate on earth:  In the period between 1645 and 1715, sun spot activity had come to a halt on the Sun, a phenomenon referred to as the Maunder minimum.  This coincided with extremely cold weather globally. So sunspots may have a relevance to climate on earth.  Such links are tenuous, but definitely solar activity affects space weather, which can have an impact on space-based satellites, GPS, power grids etc.
• Sunspots are areas that appear dark on the surface of the Sun. They appear dark because they are cooler than other parts of the Sun’s surface.
• The temperature of a sunspot is still high around 6,500 degrees Fahrenheit.
• Sunspots are relatively cool. It’s because they form at areas where magnetic fields are particularly strong. These magnetic fields are so strong that they keep some of the heat within the Sun from reaching the surface.
• The amount of magnetic flux that rises up to the Sun's surface varies with time in a cycle called the solar cycle. This cycle lasts 11 years on average. This cycle is sometimes referred to as the sunspot cycle.

How Solar Tsunami leads to Sunspot?

• The extreme temperature and pressure conditions that prevail some 20,000 km below the sun’s surface cause its material to form a plasma consisting primarily of hydrogen and helium in a highly ionized state.
• The plasma is confined with huge magnetic fields inside the sun. 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.