同学你好，该知识点来自沪江网校《新概念英语第三册【随到随学班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好~

Once we detected a planet, we would have to find a way of blotting out the light from its star, so that we would be able to 'see' the planet properly and analyze its atmosphere.

这是虚拟语气，这是一种假设的情况，与现在的事实相反，也就是说，实际情况中，现在还没有发现行星。

与现在事实相反的虚拟，句型：

If + did / were（实意动词用过去式，be动词用were） + ..., ... would/ should/ could/ might  + do （动词原形）
If I were you, I would go abroad at once.   (I am not you.)
If he knew it now, he could help me.   (He doesn't know it now.)

英语语法大全_新概念英语第三册语法总结：虚拟语气_沪江英语
http://www.hjenglish.com/yufadaquan/p170685/

期待助助的回答能帮到同学~祝学习进步~