"Dad, do you think time travel is possible?" Billy asked. "Like on Space Cadet Jake?"

"Probably not the same way it happens on television." Father tousled his son's hair and adjusted the telescope. The sky was darkening rapidly. Venus and Jupiter blazed overhead. Even Mars was visible now. Father pulled the small plastic kitchen stool from the trunk of the car so Billy could stand on it and see through the eyepiece. Billy always liked Jupiter the best. Through Father's telescope you could see the bands, the four stars that were really Galilean moons, and sometimes even the Great Red Spot. Though it was only red in the pictures. Through the telescope the entire planet was yellow.

"Why not?"

Father thought about it. By way of reply he swiveled the telescope on its tripod and pointed it instead at the face of the full moon. He didn't really need to use the laser diode to home in on it but he used it anyway so Billy could watch and learn. "Okay son," he said. "Look through the eyepiece. What do you see?"

Billy stood on his tiptoes on the stool. "Nothing."

"Just wait," Father said.

A few moments passed. "The moon!" Billy squealed, excited. "I see the edge!"

"Keep watching," Father said.

More seconds passed. "I see more of it now," Billy said. It's moving across the circle!"

"The view field," Father said. "Yes. Keep watching."

After a minute, Billy said, "It's almost gone."

"Right. Why is it gone?"

Billy thought about it. "Is the telescope moving?"

Father laughed. "Good guess! But no. It's locked into place on the tripod."

"Then the moon is moving!"

"Yep. It's orbiting the Earth."

"But what does that have to do with time travel?"

"The Earth is doing the same thing. It's orbiting the sun. Even now at this very second, it's orbiting the sun. And it's spinning around on top of that. That's why it's nighttime." Father made little motions with his hand, curling it as if around an invisible ball. "This is the sun," he said, holding up his other fist. "This is the Earth." He first turned this, and said, "Night." Then made this same hand circle the other. "Summer. Fall. Winter, spring," he said.

"I still don't understand," Billy said. "I mean I understand about the seasons and stuff but not time travel."

Father realigned the telescope with Venus. "When Jake goes back in time he's always in the same spot. If he's sitting at a table and presses the time-shift button on his wrist and jumps back five minutes in time he's still sitting at the table, right?"

"That was just on!" Billy cried. "And then he put down some glue on the seat because he knew Soran the Sauronian would come in and sit down and start being all stupid!"

"Exactly," Father said. "But think about it. Why would the table still be there? In the exact same spot. With Jake seated there in the same place?"

"I don't understand."

Father held up his fist. "Jake is here. At the table." He pointed at the knuckle of this forefinger. "Exactly right here in the present, okay?"

"Yeah."

"Okay the Earth turns, right? So if he goes back five minutes," Father paused, making his hand turn just a little bit counter-clockwise. "The table would be back where it was five minutes ago. Just like the moon would be back where it was when you first saw it in the view field five minutes ago. By now it's way over there." He pointed to where the moon was now. "You can probably barely see it, but look. Right now it's above that branch there, see? The one that looks like a 'V'? In another minute it'll move again. Watch."

Billy watched, and saw. "Oh!" he cried.

Father held up his fist again. "Okay," he said, "this is the sun." He held up his other fist. "This is Earth. And let's say it's summer. And Jake goes back in time six months. Where's the Earth?"

Billy thought about it. "On the other side of the sun!" he yelled. "Oh I get it!"

Father tested. "So if Jake went back six months in time but stayed in the same place, where would he appear?"

"In space!"

"Yep. Good thing he has a spacesuit."

"Wow, I never even thought about that!"

"A lot of people don't. Actually it's a lot more complicated. It's not just the Earth going around the sun. Everything moves. The sun moves. The whole Milky Way Galaxy moves. I'm forty-five years old. Between the time I was born, and now, the Earth has moved through trillions of miles of space. If you wanted to go back to my grandfather's time you wouldn't have to just go back in time. You'd have to travel a long, long way to get to where the Earth actually was when he was alive."

"Oh wow," Billy said. They were quiet for a time. Father focused on Mars, showing him how the ice caps looked like gleaming rainbows in the view field. But after they had packed up all the equipment and were about to head home, he had to express his disappointment. "It's too bad though, that people from the future will never visit us."

Father patted Billy's head. "Well maybe they can," he said. "They just have to be really careful with their math. So that they appear on Earth. Instead of... you know. In front of it or something. In its orbital pa--"

"Look!" Billy pointed up at the sky. "A falling star!"

Christopher Jon Heuer

The Visit