Context: The Northern Lights, also known as aurora borealis, are usually witnessed far up in the polar regions or the high latitude regions of Europe. But, they could be visible in parts of Illinois and Pennsylvania in the US.

Aurora borealis

• Northern Lights, also known as aurora borealis, are usually witnessed far up in the polar regions or the high latitude regions of Europe, like in Norway.
• But, they could be visible in regions that are more to the south, such as in the northern parts of Illinois and Pennsylvania in the US.
• This is happening due to a solar flare, which emerged from a Sunspot. The flare is accompanied by a Coronal Mass Ejection (CME) — a large bubble of radiation and particles emitted by the Sun that explodes into space at high speed.

What causes an aurora?

• Auroras occur when charged particles ejected from the Sun’s surface — called the solar wind — enter the Earth’s atmosphere.
• While flowing toward Earth, the fast-moving solar wind carries with it the Sun’s magnetic field, which disrupts the magnetosphere — the region of space around Earth in which the magnetic field of our planet is dominant.
• When the Sun’s magnetic field approaches Earth, the protective magnetic field radiating from our planet’s poles deflects the former, thus shielding life on Earth.
• However, as this happens, the protective fields couple together to form funnels, through which charged solar wind particles are able to stream down to the poles.
• At the north and south poles, the charged particles interact with different gases in the atmosphere, causing a display of light in the sky.
• This display, known as an aurora, is seen from the Earth’s high latitude regions (called the auroral oval), and is active all year round.
• In the northern part of our globe, the polar lights are called aurora borealis or Northern Lights, and are seen from the US (Alaska), Canada, Iceland, Greenland, Norway, Sweden and Finland.
• In the south, they are called aurora australis or southern lights, and are visible from high latitudes in Antarctica, Chile, Argentina, New Zealand and Australia.
• Generally, the auroral oval is confined to the polar regions. But occasionally, the oval expands, and the lights become visible at lower latitudes. This happens during periods of high solar activity, such as the arrival of solar storms.

What are the examples of high solar activity?

• Solar activities include solar flares, solar energetic particles, high-speed solar wind and Coronal Mass Ejections (CME).
• These influence the space weather which originates from the Sun. Large storms usually occur at the peak of the 11-year solar cycle, or during the three years after the peak.

Can solar flares or storms be dangerous?

• Solar flares can typically affect space-dependent operations like Global Positioning Systems (GPS), radio and satellite communications, besides hampering flight operations, power grids and space exploration programmes.
• CMEs pose danger to space weather. Ejections travelling at a speed of 500km/second are common during solar peaks and create disturbances in Earth’s magnetosphere, the protective shield surrounding the planet.
• At the time of spacewalks, astronauts face a great health risk posed by exposure to solar radiation outside Earth’s protective atmosphere.
• Such advance predictions are regularly sought out by countries who have made heavy investments in space missions. Besides, the life of functional satellites, and even those which have now turned into debris, depends a lot on the Sun’s activities.

https://indianexpress.com/article/explained/northern-lights-aurora-borealis-in-the-us-7099414/

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