Sun’s reversed polarity field may affect Earth’s climate
doi:10.1038/nindia.2018.153 Published online 26 November 2018
Unlike the earth’s magnetic field, which reverses polarity over tens of millennia, the Sun’s does so every 11 years.
Astrophysicists have now discovered an unusual pattern in the reversal of solar magnetic fields, particularly in the Sun’s poles – a phenomenon that shapes and modulates the radiations emanating from it1. This research will help monitor and assess the impact of solar activities on the Earth’s climate.
An international team including scientists from the Physical Research Laboratory in Ahmedabad, Gujarat, detected the unusual pattern of reversal of magnetic fields in the Sun during the ongoing 11-year solar cycle.
They showed that the Sun’s southern hemisphere reversed its polarity in mid-2013 whereas the reversal of the field in its northern hemisphere occurred 2.5 years later, after a sustained period of near-zero field strength.
Signatures of this field reversal were also clearly identifiable in the solar wind, a stream of charged particles that flow out of the Sun.
With the strength of the magnetic field of the Sun’s visible outer layer declining steadily over the past two decades, it is probably on the verge of a phase when sunspots, the seats of solar magnetic fields, will be entirely absent. Such periods of absence of sunspots have previously been linked to global cooling, triggering ‘Little Ice Ages’ on Earth.
This research will help understand the degree to which the solar cycle can affect near-Earth space and the Earth’s climate, says lead author Janardhan Padmanabhan.
1. Janardhan, P. et al. Solar cycle 24: an unusual polar field reversal. Astron. Astrophys. 618, A148 (2018)