Astronauts of the Shenzhou-16 spacecraft lit a candle to demonstrate how combustion worked in space, among other activities, in the latest livestreamed lecture from the nation's space station Tiangong.

The fourth of the "Tiangong Class" series was broadcast to students in Beijing, Inner Mongolia, Zhejiang, Anhui and Shaanxi on Thursday afternoon.

The lecture was given by the Shenzhou-16 astronauts Jing Haipeng, Zhu Yangzhu and Gui Haichao.

Zhu and Gui conducted the experiment on "spherical flame".

"In China's space station, the flame of the candle, actually it forms a dome shape, or spherical. But on the ground, it's more vertical... it shoots up. So that's very different in shape. Why the shape of the flame is different? Because, of course, gravity works here," Gui said.

The Shenzhou-16 mission blasted off on May 30, replacing the Shenzhou-15 crew who had been at the space station for six months.