outer reticle circle

例句：

1. 1.The discovery of the outer ring has sparked a new era in space exploration.
   外星环的发现开启了太空探索的新时代。
2. 2. The team spent months mapping out the outer ring before they could begin their mission.
   团队花了数月时间绘制外星环，然后才能开始他们的任务。
3. 3. The outer ring is believed to be home to many undiscovered species.
   外星环被认为是许多未被发现物种的家园。