ΔE 7.9, close: similar, with a visible difference side by side. RLM 70 Black Green is a little darker than Night Sky.
Usually, if you are not matching paint already on the model. Close match (ΔE 8). RLM 70 Black Green is a little darker than Night Sky.
The same difference applies the other way round: Night Sky is a little lighter.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Night Sky on the colour wheel See RLM 70 Black Green on the colour wheel
All matches: Night Sky equivalents · RLM 70 Black Green equivalents