A teacher of the affiliated kindergarten of Miaofengshan ethnic school teaches children space knowledge in Mentougou District of Beijing, capital of China, April 24, 2019. Since 2016, China has set April 24 as the country's Space Day. The various activities on Space Day have become a window for the Chinese public and the world to get a better understanding of China's aerospace progress. (Xinhua/Hou Jiqing)