APOD 1.3

This week, I chose the picture "Aurora Over Norway" (2010 September 20). The auroras are caused by the magnetic field around the Earth. The field lines go into and out of the Earth around the Earth's magnetic poles. There are also electrons and positive ions in the the surrounding magnetic field. Those charged particles move along the magnetic field lines which are like wires. When they accelerate along these lines into the upper atmosphere they collide with gas atoms. This causes the atoms to give off light. Another component of auroras is solar winds. The Sun's atmosphere is made of particles that are constantly boiling off the Sun and streaming outward at very high speeds. The Sun's own magnetic field and particles are called the "solar wind". When the wind pushes on the the Earth's magnetic field, the energy from the solar wind is constantly building up in the magnetosphere , and this energy powers auroras.

This is very interesting because I never knew how auroras were formed. And just from the picture itself, I never really took the time to look at auroras even though they are often in our textbooks with explanations. I never thought that the auroras were this bright with these many colors, and even though the sky is all lit up, the stars can still be seen. It's amazing what you can see in the sky.