[Q&A+] Getting Stuck on a Planet, Dangerous Supernovae, Expansionistic Aliens | Q&A 327

I got a Seestar but the weather has been so abysmal I haven't been able to use it yet. :( Might need to take a couple days off for an adventure to drive somewhere with a clear dark sky and camp out, looking at stars, and read another Le Guin novel.

A supernova can definitely take us out, if it promises to buy the dinner and drinks.

I just ordered a pair of celestron cometron 7x50 binocs. My first astronomy purchase!

Why do globular clusters not accrete? Too sparse for accretion yet too dense to escape each other’s gravity? ✌️🩶

I can second observing in the southern hemisphere as "better", having been to New Zealand many times (>30), for two reasons: It's much easier to find a dark sky, due to low population density; The Milky Way is really overhead! It's like just go outside on a dark night and marvel at the Milky Way seeming stretching overhead from horizon to horizon. With a decent digital camera and a bit of photographic experience you too can take pictures just like shown in the video!

Oh no not life on Mars again; there's no evidence. All we've been able to determine, after decades of exploration, is that once, a long long time ago (like > 3.8 billion years) some water flowed into lakes.

Personally I think the idea of "hostile expansionistic aliens" can be traced back to Herbert George Wells and his "War of the Worlds" - Martian invaders with superior technology. Just about every science fiction writer since has a story about Mars, aliens with a dastardly scheme etc. It's like a rite of passage for them. Unfortunately this fiction seems to have become the bread and butter of theorists and now we have so many "alien theories" that it can only be described as a tidal wave of R****h. [Sadly the R word is no longer politically correct, we're not allowed to hurt their delicate feelings].

I stumbled over the phrase "other advanced civilizations". That would imply we are amongst those? I have some doubts about that. The problems I have with the idea of expansionist and at the same time highly advanced aliens: - To become a truly advanced space-faring civilization and to master the "great filters" connected with the last steps to this goal, a civilization has to have efficient and sustainable technology (and learn to be sustainable in every aspect). A fast expansion however is not sustainable. - Colonizing other worlds is a rather slow process: Before you can use a new world as your next stepping stone, you have to develop it first. And it stands to reason that you only invest in colonizing the next world after your current colony has achieved a certain size. (Any civilization not following those rules would at least fall apart very quickly, and there is some chance that the different pieces then would compete for resources and cultural leadership, leading to wars.) It is not the speed of your spaceships which limits the speed of expansion, it is the "speed" of your economy versus the cohesion of your civilization. - Instead of colonizing a civilization could send out a bunch of "von Neumann" probes. But why? It could help to explore the neighboring star systems, but not to explore far away regions of the galaxy: The probes would take thousands of years to travel there (plus some breaks to reproduce, which would also require to collect and process resources), and the results would even if sent by laser take also thousands of years to get to your base. This would only make some sense with faster than light communication (at least).

Humans are expansionistic and we project our values on others

Ugh. I love globular clusters. They’re one of my favorite seestar targets. 🔭