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Solar Cycle 25
Why is it in News?
- NASA and the National Oceanic and Atmospheric Administration (NOAA) announced the commencement of solar cycle 25.
Details:
- Solar Cycle:
(1) Like seasons on Earth, the Sun follows a cycle of 11 years.
(2) During cycle, solar activities fluctuate between solar minima and maxima.
(3) Solar maxima is associated with highest number of sunspots while solar minima is associated with lowest number of sunspots.
(4) A new cycle commences when the Sun has reached its lowest possible minima phase.
(5) Every time the cycle changes, the Sun’s magnetic poles reverse.
(6) A Solar Cycle Prediction Panel comprising solar physicists, led by NASA and NOAA, release a consensus statement once a decade.
(7) Being the weakest in a century, solar cycle 24 was the fourth smallest in intensity since 1755.
- Sunspots:
(1) A Sunspot is an area on the Sun that appears dark on the surface and is relatively cooler than surrounding parts.
(2) These spots are the visible markers of the Sun’s magnetic field.
(3) Size of Sunspots can be as large as 50,000 km in diameter.
(4) Photosphere is the outer surface of the Sun which radiates heat and light.
(5) On the Photosphere, Sunspots are the areas where the star’s magnetic field is the strongest.
(6) Most Sunspots appear in groups that have their own magnetic field, whose polarity reverses during every solar cycle, which takes around 11 years.
(7) In every such cycle, the number of Sunspots increases and decreases.
(8) The current solar cycle, which began in 2008, is in its ‘solar minimum’ phase, when the number of Sunspots and solar flares is at a routine low.