最近他们发现了一颗彗星。用英语怎么说？

最近他们发现了一颗彗星。

Recently they have discovered a comet.

recently

adv. 最近，近来，不久以前，近日，新近；

例句
They recently failed to negotiate a mutually acceptable new contract.
他们最近未能谈成一个双方都满意的新合同。

they

pron. 他/她/它们，人们，大家，政府，当局，她们；

例句
The storms had abated by the time they rounded Cape Horn.
他们绕过合恩角时，暴风雨已经减弱。

have

aux. 用以构成完成式及完成式的不定式，表示已经…；vt. 有，具有，拿，取得，从事，必须，不得不；n. 〈口〉有产者，有钱人，富国，〈英俚〉欺骗，诈骗；

例句
He did have a real knowledge of the country...
他对该国的确知之甚多。

discovered

v. 发现( discover的过去式和过去分词 )，碰见，撞见，了解到；

例句
He had discovered politics and was rapidly becoming absorbed by it...
他接触到了政治并且迅速地对它着了迷。

comet

n. [天]彗星，孛；

例句
We were not altogether sure that the comet would miss the Earth...
我们不能完全肯定彗星不会与地球相撞。