Nocturne painting is like painting a picture in the dark! When we go to bed at night, it's usually dark outside, right? Well, some artists like to paint what they see during that time. But it's too dark to see colors properly, so they use lots of blues, blacks, and grays to create a picture that looks like it's nighttime. Think of it like coloring with only a few crayons, but making a beautiful picture anyway! Nocturne paintings can be really beautiful and mysterious, just like the night-time sky.