Hyderabad, June 8 -- A billion-tonne cloud of magnetised plasma is hurtling toward Earth at 1,400 kilometres per second, and it will produce one of the rarest light shows the night sky has to offer.

But Hyderabad will not see the nothern lights.

The Sun erupted on June 6, hurling the cloud into space. It has been travelling for two days. It arrives on Tuesday, June 8, and the Space Weather Prediction Centre has issued a G3 ("strong") geomagnetic storm watch, with brief G4 ("severe") periods possible. The storm peaks between 11:30 PM IST and 2:30 AM IST on Tuesday, June 9.

Auroras, the curtains of green, red and purple light that ripple across the sky when charged solar particles collide with gases in the upper atmosphere, could be visi...