Knut Lundmark was one of the pioneers in the modern study of the galaxies and their distances. He was one of the first to suspect that the galaxies are remote stellar systems at vast distances and not nearby objects belonging to our own galaxy, the Milky Way. In 1919 he measured the distance to M31 – the Andromeda Galaxy, to 650,000 light years (about a fourth of the present day value) using magnitudes of novae found in M31 and comparing them to nearby ones with known distances. Lundmark's work contributed to the later famous Great Debate over whether nebulae were galaxies or concentrations of glowing gas.