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In April last year, Earth saw beautiful auroras spreading far across regions where the phenomenon never even happens. A coronal mass ejection on April 21 triggered a G-4 class geomagnetic storm on Earth on April 23, 2023. It even reached Ladakh in India. Auroras happening at such low altitudes are rare. Now NASA has revealed that something else phenomenal and strange also happened during the solar storm. 

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NASA Sun & Space shared on X (earlier Twitter) that for a brief period during the solar storm, a two-way “highway” formed between the Sun and Earth. Explaining it further, NASA said that this highway meant that "the usual one-way flow from the Sun to Earth suddenly went both directions: For about two hours, Earth was also spewing particles back into the Sun!" NASA’s MMS spacecraft flew through this path and collected data.

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The particles sent back to the Sun from Earth collided with the Sun’s atmosphere and created an aurora on the Sun, the NASA page says. How did this strange occurrence take place? 

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How did the highway between Sun and Earth form?

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NASA explains that as the solar eruption paced towards our planet, Earth was completely engulfed by the particle cloud. During this time for a brief moment, a part of Earth’s magnetic “shield” dissipated. However, we were still very much protected by the radiation emitted by the Sun. This dissipated part is called Earth’s “bow shock.” Imagine a boat moving on water, its front part creating frothy waves. Something similar happened when our bow shock created a barrier against incoming solar particles. This bow led the particles to “splash” against it.

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With the bow shock not there, the magnetic field within the solar eruption fused with Earth’s magnetic field. Earth’s magnetism had been holding onto particles which suddenly found an escape, and moved directly on a path towards the Sun. This highway is scientifically known as “Alfvén wings" and is rare on Earth. However, they are quite common on some other celestial bodies in our solar system, such as Jupiter’s moons. Alfvén wings is the path particles from Galilean moons Io and Ganymede take to reach Jupiter, adding to Jupiter’s ultraviolet aurora, the NASA post says.