但有个问题，金星凌日很难得。

But there was a problem. Transits of Venus are rare.

youdao

这就是所谓的凌日行星。

It is what is known as a transiting planet.

youdao

同时也标注了另一个日子，6月6号，这一天将发生金星凌日。

They also marked another date, June 6, the transit of Venus across the sun.

youdao

同时也标注了另一个日子，6月6号，这一天将发生金星凌日。

They also marked another date, June 6, the transit of Venus across the sun.

youdao