Photo taken on July 27, 2019 shows a rainbow over the Ming'antu observing station of the National Astronomical Observatories of the Chinese Academy of Sciences, in Zhengxiangbai Qi, north China's Inner Mongolia Autonomous Region. (Xinhua/Liu Lei)

Photo taken on July 27, 2019 shows a rainbow over the Ming'antu observing station of the National Astronomical Observatories of the Chinese Academy of Sciences, in Zhengxiangbai Qi, north China's Inner Mongolia Autonomous Region. (Xinhua/Liu Lei)

Photo taken on July 27, 2019 shows a rainbow over the Ming'antu observing station of the National Astronomical Observatories of the Chinese Academy of Sciences, in Zhengxiangbai Qi, north China's Inner Mongolia Autonomous Region. (Xinhua/Liu Lei)

Photo taken on July 27, 2019 shows a rainbow over the Ming'antu observing station of the National Astronomical Observatories of the Chinese Academy of Sciences, in Zhengxiangbai Qi, north China's Inner Mongolia Autonomous Region. (Xinhua/Liu Lei)

Photo taken on July 27, 2019 shows a rainbow over the Ming'antu observing station of the National Astronomical Observatories of the Chinese Academy of Sciences, in Zhengxiangbai Qi, north China's Inner Mongolia Autonomous Region. (Xinhua/Liu Lei)