A group from IISER Kolkata has recenly shown that the next sunspot cycle has begun.
More about the news:
- Start of cycle 25 in contradiction 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 the 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.
Colder Areas on the Sun’s surface
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 very hot around 6,500 degrees Fahrenheit.
Why are sunspots relatively cool?
- It’s because they form in 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.
Sunspots originate deep within the Sun and become visible when they pop out.
Sunspots occur in pairs, with a leader and a follower.
Mechanism of generation of Sunspots
- Given the high temperatures in the Sun, matter exists there in the form of plasma, where the electrons are stripped away from the nuclei.
- The Sun is made of hot ionised plasma whose motions generate magnetic fields in the solar interior by harnessing the energy of the plasma flows.
- This mechanism is known as the solar dynamo mechanism (or magnetohydrodynamic dynamo mechanism).
- It is a process by which kinetic energy of plasma motions is converted to magnetic energy, which generates the magnetised sunspots, giving rise to the solar cycle.
The reversal in magnetic field in the Sun and the association with SunSpots
- Because of the nature of the solar dynamo, the part of its magnetic field that gives rise to sunspots reverses direction when it moves from one solar cycle to another.
- This can be inferred by observing when the relative orientation of the sunspot pairs flip.
About Solar cycles
The number of Sunspots is not constant but shows a minimum and then rises up to a maximum and then falls again in what is called the solar cycle.
So far, astronomers have documented 24 such cycles, the last one ended in 2019.
The number of the Sunspots waxes and wanes in cycles that last 11 years approximately. We are currently at the minimum of one such cycle.
Origin of solar flares and coronal mass ejections from Sunspots:The Sun appears to be sedate and constant from a large distance. However, huge solar flares and coronal mass ejections spew material from its surface into outer space.
About NASA’s SDO: The Solar Dynamics Observatory
It is the first mission to be launched for NASA's Living With a Star (LWS) Program,
- This program is designed to understand the causes of solar variability and its impacts on Earth.
It is designed to help us understand the Sun's influence on Earth and Near-Earth space by studying the solar atmosphere on small scales of space and time and in many wavelengths simultaneously.