Group 1 - The phenomenon observed in the sky on the evening of August 28 is referred to as "dawn twilight bands," commonly known as "曙条" in Chinese, which is a type of atmospheric optical phenomenon caused by the scattering of sunlight in the upper atmosphere [4][8] - This phenomenon was seen across multiple cities in the Jiangsu, Zhejiang, and Shanghai regions, including Nanjing, Shanghai, and Hangzhou, where beautiful dawn twilight bands and anti-dawn twilight bands were reported [6][8] - The occurrence of this phenomenon just before the traditional Chinese festival of Qixi adds a layer of mystique to the celebration, as this year's Qixi festival falls on August 29, the latest date in the 21st century due to the leap month in the lunar calendar [10] Group 2 - The Qixi festival, also known as the Double Seventh Festival, is traditionally celebrated on the seventh day of the seventh month in the lunar calendar, and this year it is notably delayed compared to previous years [10] - The leap month in the lunar calendar has caused the Qixi festival to be pushed back, with the last occurrence of the festival on August 10 in the previous year [10] - Future occurrences of similarly delayed Qixi festivals are expected in 2055, while the earliest Qixi festival in this century was on July 31, 2006 [10]