Elementary school students visit a planetarium in Lhasa, southwest China's Tibet Autonomous Region, Dec. 14, 2019. An planetarium opened its door to the public for trial operation in Lhasa on Saturday.(Photos: Xinhua)

Visitors are seen at a planetarium in Lhasa, southwest China's Tibet Autonomous Region, Dec. 14, 2019. An planetarium opened its door to the public for trial operation in Lhasa on Saturday.

An planetarium opened its door to the public for trial operation in Lhasa on Saturday.

Visitors are seen at a planetarium in Lhasa, southwest China's Tibet Autonomous Region, Dec. 14, 2019. An planetarium opened its door to the public for trial operation in Lhasa on Saturday.

Elementary school students visit a planetarium in Lhasa, southwest China's Tibet Autonomous Region, Dec. 14, 2019. An planetarium opened its door to the public for trial operation in Lhasa on Saturday.

Visitors are seen at a planetarium in Lhasa, southwest China's Tibet Autonomous Region, Dec. 14, 2019. An planetarium opened its door to the public for trial operation in Lhasa on Saturday.

A visitor takes photos at a planetarium in Lhasa, southwest China's Tibet Autonomous Region, Dec. 14, 2019. An planetarium opened its door to the public for trial operation in Lhasa on Saturday.