ΔE 10.1, fair: the same colour family, but not a straight swap. Blue FS15050 is a little darker, warmer than Night Sky.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 10). Blue FS15050 is a little darker, warmer than Night Sky.
The same difference applies the other way round: Night Sky is a little lighter, cooler.
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 Blue FS15050 on the colour wheel
All matches: Night Sky equivalents · Blue FS15050 equivalents