Students attend the fourth live class of the "Tiangong Class" series in Yan'an Science and Technology Museum in Yan'an, northwest China's Shaanxi Province, 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. (Photo by Deng Zhihong/Xinhua)