Stretching over 100 light-years and located about 1,000 light-years away in Perseus, the California Nebula is one of the largest emission nebulae in the sky — but its extremely low surface brightness makes it surprisingly difficult to photograph from light-polluted sites. It is ionised almost entirely by a single star, Xi Persei (Menkib), a luminous blue giant blazing with the power of roughly 263,000 Suns.