Murmansk's appearance in May was not extreme day, but white night. Because of the relationship between the deflection of the earth's axis and the revolution of the earth's rotation, in high latitudes, sometimes dawn appears before dusk has passed. The sun can only reach a small angle below the horizon. Due to the scattering of the atmosphere, it was not completely dark all night. Near the Mohe River in the northernmost part of China, when summer approaches the summer solstice, there will be white nights. The area where the white night appears starts from 48 34' north latitude. The higher the latitude, the longer the white night appears and the brighter the sky. After reaching the Arctic Circle (66 34'), it became extremely bright. So Murmansk started with a white night in May, then it was extremely bright, and then it became a white night. 69 is far from 48 34'. In China, Hulunbeier, Heihe and Daxinganling areas can all see white nights.