Question

求教英语高手！

For all his achievements, however, Halley's greatest contribution to human knowledge may simply have been to take part in a modest scientific wager with two other worthies of his day: Robert Hooke, who is perhaps best remembered now as the first person to describe a cell, and the great and stately Sir Christopher Wren, who was actually an astronomer first and an architect second,though that is not often generally remembered now.

his day是什么意思，在这里是什么结构？

Answer 1

不幸的是，空间浩瀚，任何两个文明社会之间的平均距离据测算至少在200光年，而这个（空间如此的浩瀚的概念）超出了所能用言语表达的范围。

which 后面一个非限定性定语从句，指代前面的那个句子，因此，我用而这个（空间如此的浩瀚的概念）来概括

more than merely saying ，有点像，i love you more than i can say 的表达，只不过，这里的than 做介词，因此用了saying 动名词，i love you more than i can say 的than 做了连词，因此用了句子

it makes it sound是say 的宾语部分，字面意思是就是超过他听上去的这么的浩瀚，需要意译
这样可以么？
求采纳为满意回答。

Answer 2

of his day在他所处的时代的意思，作定语修饰前面的two other worthies“，翻译为 “在他所处时代的另外两名杰出人物”

of one's day某人所处的时代