Summer Solstice is the best season for viewing the aurora. [File Photo]

The longest day of the year

On the Summer Solstice itself, daylight lasts the longest for the whole year in the northern hemisphere. After this day, daylight hours get shorter and shorter and temperatures become higher in the northern hemisphere.

How long is the longest day in China? According to the expert Yan Jiarong, the entire day in Mohe in Helongjiang province, located in the northernmost tip of China, lasts nearly 17 hours when you include dawn, twilight and its afterglow. Summer Solstice is the best season for viewing the aurora in Mohe, "the sleepless town of China".