Where does the "outer space" in the song of the Yangtze River refer to?

Source: Gladandong Snow Mountain in Tanggula Mountains of Qinghai-Tibet Plateau. The total length of the river is 638Km, which is the third largest river in the world and the largest river in China. The ranking of rivers in the world: first, the Nile (Africa and Egypt); Second, the Amazon River (Brazil in South America); Third, the Yangtze River (Asia, China) covers an area of 1.8 million square kilometers, ranking first in China. It flows through nine provinces and two cities: (pointing to the map) Qinghai → Sichuan → Tibet → Yunnan → Chongqing → Hubei → Hunan → Anhui → Jiangxi → Jiangsu → Shanghai Estuary, and it flows into the East China Sea through Shanghai Wusongkou.

The Yangtze River is the largest river in China, which was called "Great River" in ancient times. It flows through Tibet, Sichuan, Yunnan, Hubei, Hunan, Jiangxi, Anhui, Jiangsu and other provinces, and flows into the East China Sea in Shanghai. There are 742 cities and counties in the river basin, with a total population of nearly 4 million and a total area of more than 1.8 million square kilometers. There are tributaries such as Yalong River, Minjiang River, Tuojiang River, Jialing River, Wujiang River, Xiangjiang River, Hanjiang River, Ganjiang River, Qingyi River and Huangpu River.

The Yangtze River intersects the Grand Canal in Zhenjiang, Jiangsu Province. Above Yichang City, Hubei Province, it is upstream, with many rapids; Yichang to Hukou, Jiangxi Province is the middle reaches, with developed meanders and many lakes (Poyang and Dongting are the largest); Below the mouth of the lake is Chongming Island, which is downstream, wide and impacted by the estuary.

The Yangtze River is rich in water and hydraulic resources. When the water is abundant, 1,-ton ships can reach Wuhan, and small ships can go back to Changyi. Important cities along the Yangtze River include Chongqing, Wuhan, Nanjing and Shanghai.

There are at least 3 kinds of names and aliases for the main reaches of the Yangtze River. Yibin to Yichang City, Hubei Province, as most of it flows through Sichuan Province, is commonly known as Chuanjiang. The Yangtze River bends into several shapes near Jiangjin, Sichuan, also known as "Jijiang". The reach from Baidicheng, fengjie county, Sichuan to Yichang Three Gorges, commonly known as Xiajiang. Zhicheng, Hubei Province to Chenglingji, Yueyang City, Hunan Province, is commonly known as "Jingjiang River" because it flows through the ancient Jingzhou area. This river twists and turns, known as the "nine-bend ileum". Jiujiang City, Jiangxi Province was called Xunyang in ancient times, and the nearby section of the river was also called Xunyang River.

Not long ago, scientists re-measured the Yangtze River and found that its length was 6,211.3 kilometers, which was more than 8 kilometers shorter than the recognized 6,3 kilometers. However, this result did not change the position of the Yangtze River as the longest river in Asia and the third longest river in the world. The length of the Yangtze River section is as follows: Dangqu (from the source to Nangji Balong) is 36.8 kilometers, Tuotuo River is 357.6 kilometers, Tongtian River is 787.7 kilometers, Jinsha River is 2322.2 kilometers, and Yibin is 274.6 kilometers.

With its rich resources, the Yangtze River irrigates the motherland and nurtures children of all ethnic groups. The Yangtze River, with its vast river basin, connects the majestic mountains in the west with the vast sea in the east. In the new era, the water of the Yangtze River has irrigated the land of the motherland more fertile, and contributed to the promotion of the four modernizations with a brand-new attitude. Therefore, it can be said that the Yangtze River is an "infinite source" and "has the feelings of a mother".