Physicists predict a Solar Deepavali this year

The sun may well add to this year’s Deepavali celebrations, if predictions made by solar physicists come true. A solar flare that occurred on the Sun has triggered a magnetic storm which scientists predict will arrive at the Earth in the early hours of November 4, and this can give rise to spectacular displays of aurora in the polar regions, just in time for the Deepavali celebrations in India. 

The solar magnetic cycle that works in the deep interior of the Sun creates regions that rise to the surface and appear like dark spots. These are the sunspots. Solar flares are highly energetic phenomena that happen inside the sunspots. In a solar flare, the energy stored in the sun’s magnetic structures is converted into light and heat energy. This causes the emission of high energy x-ray radiation and highly accelerated charged particles to leave the sun’s surface. Sometimes solar flares also cause hot plasma to be ejected from the Sun, causing a solar storm, and this is called Coronal Mass Ejection (CME). Coronal Mass Ejections can harbour energies exceeding that of a billion atomic bombs. 

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The energy and radiation and high energy particles emitted by flares can affect Earth bound objects and life on Earth – it can affect the electronics within satellites and affect astronauts. Very powerful Earth-directed coronal mass ejections can cause failure of power grids and affect oil pipelines and deep-sea cables. They can also cause spectacular aurorae in the high-latitude and polar countries. The last time a major blackout due to a coronal mass ejection was recorded was in 1989 – a powerful geomagnetic storm that took down the North American power grid, plunging large parts of Canada in to darkness and triggering spectacular aurorae beyond the polar regions.

A team of solar physicists from CESSI, in IISER Kolkata, which included PhD student Suvadip Sinha and Prof. Dibyendu Nandi, have predicted that a collection of sunspots denoted active region 12887 and 12891 could erupt into a so-called X-class flare and several M-class flares. These are the types of flare that are strongest and second strongest in terms of the intensity of x-ray radiation that they carry. This prediction has already proven to be true. The team expects the CME triggered by the M class flare that occurred in sunspot 12891 to impact the Earth with speeds upwards of 700 km/s late in the night of November 3 or early on November 4. According to Dibyendu Nandi, “This storm may well be dubbed the “Diwali solar storm,” in keeping with the naming of storms after Bastille Day (2000), Halloween Day (2003) or St Patrick’s Day (2015).”

If the storm is strong enough, it could cause lighting effects or aurorae in the polar regions. Prof Nandi said, “Often when the solar wind speed is high and the magnetic field component in the wind is in the right orientation, auroras are triggered. For example, there is an auroral oval which is confined just over the poles which is often visible from space crafts. However, only during a storm does the aurora become more spectacular and become visible in countries like Canada, Northern USA, Sweden, Finland, Norway, Siberia etc.”