Explained: How Solar Storms Cause Colourful Auroras On Earth – NDTV

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NASA said that because solar flares are light, they reach Earth in about 8 minutes.

New Delhi:

Auroras illuminated the skies across many regions on Saturday. This was the second time in a row on May 11 that auroras lit up the skies across swaths of the planet.

This spectacular celestial show, which is usually confined to the far northern reaches of the planet and is called “northern lights”, is triggered by a powerful solar storm.

A report by news agency AFP stated that this powerful solar storm could also continue on Sunday.


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Why do we get auroras?

The National Aeronautics and Space Administration (NASA), on Sunday, shared a thread on X (formerly Twitter) explaining the phenomenon.

NASA explained the two things that they call solar eruptions—solar flares and coronal mass ejections (CMEs).

NASA wrote, “There are two things we call solar eruptions: solar flares and coronal mass ejections (CMEs). They often occur together, but not always. Solar flares are intense flashes of light — a result of the Sun’s complex magnetic fields abruptly rearranging themselves.”

Talking about CMEs, it added, “Coronal mass ejections (CMEs) are giant clouds of solar particles laced with magnetic fields that escape from the Sun. These giant clouds can travel anywhere in the solar system, including to us here on Earth.”

NASA said that because solar flares are light, they reach Earth in about 8 minutes, while CMEs can take days to reach us. However, when they do they can set the aurora light.

“Solar flares reach us quickly — light only takes about 8 minutes to reach Earth. Because CMEs are made up of particles, they may take days to reach us. But when they do, they can set the aurora alight,” added NASA.

In addition, when these CMEs collide with Earth’s magnetic field, they dump “solar particles into near-earth space.” Now, these particles dive into earth’s atmosphere in a ring “around the poles, called auroral oval.”

“When a CME collides with Earth’s magnetic field, it can dump solar particles into near-Earth space. These particles follow Earth’s magnetic field lines as they dive into our atmosphere in a “ring” around the poles called the auroral oval,” NASA wrote.

After these incoming particles strike gases, present in Earth’s atmosphere, it heats up and starts glowing. NASA stated, “The incoming particles strike gases in our atmosphere, causing them to heat up and glow: the aurora. The colours depend on the type of gas and its altitude. Oxygen glows red or blue; nitrogen can be green, blue, or pink.”

Sharing a glimpse of last night’s northern lights reported in the Bahamas, NASA wrote, “Powerful, repeated eruptions like those we’ve had recently can widen the auroral oval, pushing aurora to lower latitudes. Last night, northern lights were reported as far south as the Bahamas!”

Meanwhile, from northern Europe to Australia’s Tasmania, the sky-gazers last night witnessed stunning auroras that painted the skies in pink, green, and purple.

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