In some places, the beautiful aurora is often seen at night, and this strange and mysterious aurora has always attracted us. The aurora is generated by high-energy particles (electrons and protons) from outside the atmosphere hitting atoms in the upper atmosphere. It is now known that as part of the solar wind, charged particles are captured by the Earth's magnetic field when they reach near the earth. They collide with the atoms of oxygen and nitrogen, killing the electrons and turning them into exciting ions. These ions emit radiation of different wavelengths. Aurora is produced in red, green or blue. The formation of aurora is closely related to solar activity. Every year when the sun is active, you can see a more spectacular aurora scene. When night comes, red, blue, and green The light filled the night sky and the scene was extremely spectacular. The most suitable for this text title is:. ['Aurora is still not visible in most areas.', 'Aurora formation is related to solar activity.', 'The aurora scene is extremely spectacular.', 'How Aurora is formed.']