Aurora Borealis or the Northern Lights (Picture of the Day)

Aurora Borealis over Canada
An aurora is a light in the sky which can be viewed with naked eye. Aurora which could be seen in the northern hemisphere is called the Aurora Borealis or the Northern Lights. It is caused when the highly-charged particles radiated from the sun, called solar wind, interacts with the Earth's magnetic field. Although most particles are deflected by the Earth's magnetic field, some particle enters the earth through the gap in the magnetic field near the poles. As these particles approach the upper atmosphere (magnetosphere),  it collides with the gas particles and produce these coloured lights. The colour of the light varies depending on the type of gas particle it collides with - Oxygen emits either a greenish-yellow light or a red light; nitrogen generally gives off a blue light. The blending of these colors can also produce purple, pink or even white coloured lights. This is the most visible Sun's effect in the Earth's atmosphere. Most of the auroras occur in between 50 miles and 200 miles above Earth's surface.

The picture above is taken from the International Space Station. The Aurora Borealis is above the city of Winnipeg, Canada.




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