The World's Greatest Super Friends - Season 1 Episode 2 Lex Luthor Strikes Back

In an attempt to take over the world, Lex Luthor calls on the help of strange solar creatures from the sun. Lex successfully imprisons all the Superfriends (except the Wonder Twins, who are vacationing on their home planet Exxor), as the solar cretaures turn the sun from yellow to red. The yellow rays of the sun gives Superman his powers, so the red sun makes him no stronger than the average human. However, the solar creaturs have their own agenda and beging to torch the entire planet, and leave Lex to die. In an act of desperation, Lex releases the Superfriends so they can get rid of the solar creatures and return them to the sun. Lex is then captured by the Superfriends.