Chinese astronauts conducted a science lecture 400 kilometers above Earth to millions of students on Thursday afternoon, as they orbited in the Tiangong space station.

Major General Zhai Zhigang, Senior Colonel Wang Yaping and Senior Colonel Ye Guangfu, all members of the Shenzhou XIII mission crew, greeted students, teachers and other participants when the lecture started at 3:54 pm. They showed viewers how they live and work inside the space station, which currently consists of a core module, a spacecraft and two robotic cargo spaceships.