Mitosis results in two daughter cells having the same number and kind of chromosomes.
We rely on Meiosis so that we can produce/have genetic diversity. It also enables us to have proper conditions for reproductive success.
The four astronomical bodies would be milky way, universe, planets and stars ur welcome
The result of non-reproduction is simple.
There will not be another generation of a species. Without a new generation, the parents would die off, and there would be nothing to carry on the name they had both shared.
Hope this helps! ( °ω° )