Apollo and his twin sister Artemis were the children of Zeus, the king of the Greek gods, and the goddess Leto. When Leto became pregnant, Zeus already had a wife, the queen of the gods Hera. Hera was angry that Zeus was having children with Leto, and cursed Leto so that she could not ever give birth to her children anywhere on the earth where the sun shone. Hera then sent a serpent called Python to eat her. Python chased Leto to the edge of the sea, where Leto swam to the island of Delos. Python could not swim, however, and had to leave her alone. The island of Delos was at that time just a big rock floating on the sea, not an island yet, so it wasn't "on the earth". So Leto climbed under the shade of a palm tree and gave birth to her daughter Artemis, and then her son Apollo. Delos then became Apollo's and Artemis' sacred land. It varies from myth to myth what twin was born first.