8 questions with no upvoted or accepted answers
1k views

### How soon can the first stars form?

Introduction In our universe, the cosmic microwave background was formed approximately 400,000 years after the Big Bang. It was hot, but within a few million years after the Big Bang, it would no ...
290 views

### Plausibility of helium dominated atmospheres on super-Earths

I've been using this helpful diagram a lot for worldbuilding. Now I came to think about the fact that helium is more massive than hydrogen, thus a scenario where hydrogen escapes, but helium is ...
175 views

### Schwarzschild Metric in a universe with the same space time metric as that described in the orthogonal series, but with massive gravitons?

The universe described in the orthogonal series http://www.gregegan.net/ORTHOGONAL/00/PM.html is one, in which the minus sign in the space time interval is replaced with a plus sign. So this universe ...
62 views

### Appropriate Material for a Red Moon

I have some ideas regarding this, but thought I would check to see what you guys can come up with, as I found some of the ideas here often trump mine in originality and/or plausibility. So, I have a ...
121 views

### Can a system of 10 planets be stable if star is not on the main sequence?

My star is 2.17 Solar masses. For narrative purposes, I decided this so it will collapse in the theoretical Quark star. Could such a big star that isn't on the main sequence (Because its an A type, ...
30 views

### How to find the density of a planet and its core taking into account the gravitational compression in them?

Consider a planet $P$ of radius $r$ larger than Earth, whose mass is $r^3$. By the square–cube law, this planet will have the same density as the Earth... assuming that the gravitational compression ...