The constellation Cassiopeia is significant in mythology as it represents the vain queen from Greek legends. In various tales, she is depicted sitting on a throne and is known for boasting about her beauty, claiming to be more beautiful than the Nereids, sea nymphs admired for their grace. This hubris angers the gods, leading to consequences for her and her husband, King Cepheus. As a result, they sacrifice their daughter Andromeda to appease the deities. Cassiopeia's connection to the stars serves as a reminder of the consequences of vanity and the balance between beauty and humility in human behavior.