The Day The Earth Froze is the 33rd produced episode and the 33rd Broadcast episode of the series Fireball XL5
A note in the hand of an unconscious Patrol crewman leads Fireball XL5 to the ice planet Zavia. At Space City snow falls and soon everything is frozen solid. On Zavia, two Jedums, Cardre and Rader, capture the crew and tell them that they plan to defect the sun's rays using a giant reflector, thereby destroying Earth. Steve Zodiac is able to use a belt buckle to chip a staircase into the wall of their ice jail, and they escape in Fireball Junior. They use a missile to destroy the giant reflector and thus save Earth.
- Zoonie and Eleanor appear, but have no dialogue.
- Venus dialogue at the end of the episode suggests that she has never been to Switzerland, meaning that this episode must take place before Drama At Space City.