They Lied

Penny looked at the spacecraft flying by her window.
"Dad, are more people from Earth coming to Mars?"
"Nope. Everyone's here."
"Really? Why do we have so much extra space then?" she asked.
"Mars is big. Your science teacher said that Mars was not that different in size, but she was lying."
"Why would she lie?" Penny asked.
"That was what people did to convince us that moving here was a bad idea, but as you can see, we're fine," he said as he searched for an oxygen tank and turned off the news of Earthlings prospering with more space.