Students attend the fourth live class of the "Tiangong Class" series at Beihang University in Beijing, capital of China, Sept. 21, 2023. The fourth live class from China's space station was held on Thursday afternoon, delivered by the Shenzhou-16 astronauts Jing Haipeng, Zhu Yangzhu and Gui Haichao to students on Earth. (Xinhua/Ju Huanzong)