Aurora

     Aurora is a natural phenomenon that is a display of natural coloured light in the sky. It is caused due to the collision of electrically charged sun particles with the gases such as oxygen and nitrogen present in the earth's atmosphere. The colours usually seen are green, yellow, and white. When the collision takes place with oxygen the colours that occur are yellow and green while the collision with nitrogen produces red, violet, and sometimes blue.

      They are also called polar lights as they occur only in the poles. There are two types of aurora- Northern lights (Aurora Borealis) and Southern lights (Aurora Australis). 

 The northern lights can be viewed in the Arctic Circle, Alaska, Canada, Iceland, Greenland, Norway, Sweden, and Finland. There are five different types of Aurora Borealis.

• Arc- Long graceful curves that go horizon to horizon. It is the most common shape and is seen during low solar activity.
• Bands-Similar to arcs but have more curves. Arcs can change into bands within mere minutes.
• Corona-Shape of a crown. It has a lot of colors- pink, purple, blue and white. They are common during intense solar activity.
• Diffuse- Occurs on rare occasions. They don't have a specific shape. Specialized equipment is required to view it.
• Rays- Appears as streaks in the sky. When arcs curl on themselves they are formed. It is common during high solar activity.

     The southern lights are named by Captain James Hook as Australis in Latin means 'southern'. It can be viewed in Tasmania, New Zealand, and Antarctica. They are mostly dazzling green and sometimes red. The last sighting of these lights was 20 March 1950. The northern lights are more common compared to the southern lights.

Credits: Harini