From UPSC perspective, the following things are important :
Prelims level : Sun’s Rotation
Mains level : Not Much
Scientists at Kodaikanal Solar Observatory have estimated how the Sun has rotated over a century from data extracted from old films and photographs that have been digitized.
Try this PYQ:
Q.Consider the following phenomena:
- Size of the sun at dusk
- Colour of the sun at dawn
- Moon being visible at dawn
- Twinkle of stars in the sky
- Polestar being visible in the sky
Which of the above are optical illusions?
(a) 1, 2 and 3
(b) 3, 4 and 5
(c) 1, 2 and 4
(d) 2, 3 and 5
- The Sun rotates around an axis that is roughly perpendicular to the plane of the ecliptic; the Sun’s rotational axis is tilted by 7.25° from perpendicular to the ecliptic.
- It rotates in the counterclockwise direction (when viewed from the north), the same direction that the planets rotate (and orbit around the Sun).
- The Sun’s rotation period varies with latitude on the Sun since it is made of gas.
- Equatorial regions rotate faster than Polar Regions.
- The equatorial regions (latitude = 0 degrees) rotate in about 25.6 days. The regions at 60 degrees latitude rotate in about 30.9 days. Polar Regions rotate in about 36 days.
Key observations of the study
- The Sun rotates more quickly at its equator than at its poles.
- Over time, the Sun’s differential rotation rates cause its magnetic field to become twisted and tangled.
- The tangles in the magnetic field lines can produce strong localized magnetic fields.
- When the Sun’s magnetic field gets twisted, there are lots of sunspots.
- The sunspots which form at the surface with an 11-year periodicity are the only route to probe the solar dynamo or solar magnetism inside the Sun and hence measure the variation in solar rotation.
- This estimation would help study the magnetic field generated in the interior of the Sun, which causes sunspots and results in extreme situations like the historical mini-ice age on Earth (absence of sunspots).
- It could also help predict solar cycles and their variations in the future.