Spiral galaxy NGC 925, optical image. NGC 925 is a spiral galaxy with well-defined arms. There are regions of emission nebulosity within the spiral arms. The pink emission nebulae are where hot young stars ionise hydrogen gas and cause them to glow red. The blue reflection nebulae are due to dust and gas clouds reflecting starlight, where blue light is scattered more than red light. NGC 925 lies about 31 million light years from Earth, in the constellation Triangulum.