In 1924, it was discovered that the closest such nebula, Andromeda, was actually a galaxy itself ​ — some two million light years away!
याउलट, काही ग्रीक तत्त्वज्ञान्यांची अशी धारणा होती की प्रकाश हा मानवी नेत्रांतून उत्पन्‍न होतो.