Counter-Earth

S2, E21: The cadets find an old book called Counter-Earth in Coot's workshop, and are astonished to read about Earth's identical twin planet on the other side of the Sun. Why has no one told them about this before?! Determined to be first to discover it, Eagle, Robyn and Hawk set off the next morning. Completing a broad arc around the Sun, AVA announces that they've arrived at their destination. But the more they explore, the more they realize they've landed on Mars. Perhaps they flew too far, AVA suggests. So they blast off to try again... and again... yet each time, the kids find themselves on a familiar planet. But their exhausting search pays off when they finally discover a planet that's just like Earth. Only problem is... it IS Earth. Huh?? Turns out, it's all been an April Fools joke by the teachers and AVA. Counter-Earth is science fiction, not science fact!