Sci-Fi novels that involve first contact with aliens/space or time travel

Hiii all! My favorite television shows & movies have always surrounded space, its travel, aliens and other sci-fi elements such as that. (My current favorite TV show & the only one of three that I have watched in the last year & a half, is For All Mankind.)

Anyways, I recently read ‘Atmosphere’ by Taylor Jenkins Reid and enjoyed it, and just got finished “ the Shackleton Signal” which is about an a race to the moon between the USA + China to uncover an alien artifact that sent a signal. I’ve read Ender’s Game before many years ago, but I want something

I was wondering what everyone’s favorite novels that would fall under that genre would be?

Thanks in advance, and happy reading, my fellow book lovers/nerds/enthusiasts. (I proudly admit all 3 titles belong to me, haha.)