Ask HN: What are some good newsletters that you enjoy reading?

Hi HN!

I've seen a decent number of people recently talking about email newsletters with good content on stuff like space exploration, science, and cryptography that they enjoy reading.

Wondering if anyone has suggestions for good ones to subscribe to (obviously doesn't have to be limited to the couple of things I mentioned).

These definitely seem like an interesting form of information consumption, so I'd also be interested in hearing what you think of them as a medium.