“There’s no gravity in space.”

“Oh yes there is.”

“No there isn’t,” Gregory said leaning forward.

“Yes,” Jennifer insisted with both hands on her hips. “There is!”

Gregory raised his voice. “I don’t get you. Our whole lives we’ve seen movies and videos of astronauts floating around inside and outside the shuttle or space station. And they’re always talking about zero-gravity and weightlessness. You’ve seen how their food floats…”

Jennifer raised both hands above her head and lowered them. “That’s because they’re all falling.”

“What do ya’ mean they’re all falling.” Gregory lowered his eyebrows. “They stay up in space for weeks. When they’re in the vacuum of space, there is no gravity. I don’t know exactly how to explain it, but my dad’s an engineer. He’ll know what’s going on.”

Gregory couldn’t focus on his homework thinking about the argument he had with his friend after class that day. He picked up his pen quickly and lowered his head when he heard a familiar knock on his bedroom door.

“Who is it?”

“It’s dad.”

“Oh, come in.”

“You getting your homework done?”

Mr. Jackson, a thin, medium height man with dark hair on both sides of a balding head, entered the room. “You doing biology, or history?” Mr. Jackson pulled up a chair and sat next to Gregory.

“I wish. I can’t focus. You need to help me solve an argument with Jenn.”

“Who’s Jenn?”

“Oh, Jennifer is this girl in my biology class.”

“I’m a mechanical engineer,” Mr. Jackson said, “not a biologist, but I’ll give it a try. So what’s the problem.”

“It’s not about biology. She thinks that when you get out into space, there’s gravity out there. I tried to explain it to her but she thinks she’s so smart.”

Mr. Jackson opened his mouth, but closed it again, and just shifted his position and listened.

“She thinks everything in space is just somehow falling forever and never crashing into the Earth.” Gregory noticed his fathers unusual patience and stopped, turning is his dad’s direction. “So how would you explain it, you have a master’s degree.”

“Boy, this is kind’a embarrasing.” Mr. Jackson squinted and pinched his chin.

“No kidding,” Gregory said. “Have you ever had to tell a girl she’s wrong.”

“No,” Mr. Jackson said as he scratched the skin on the top of his head. “I mean, I didn’t realize I never explained this to you.”

“Explained what?”

“I thought,” Mr. Jackson said and paused. “I thought you understood Newtons laws, and gravity. I thought everyone understood.”

Gregory didn’t know what to say.

Mr. Jackson looked his son straight in the eye. “It takes gravity to keep spacecrafts in orbit.”

“To keep them in orbit? But I thought…,” Gregory said.

“Actually,” Mr. Jackson continued, “there is gravity everywhere. Where ever there are planets, moons, or galaxies, where ever there is mass in the neighborhood of space, there is gravity.”

Gregory’s jaw hung wide open. “So they ARE falling. Then why doesn’t the space craft and the astronauts fall all the way back to the Earth?”

“The Earth is pulling on the space craft almost as much as the Earth is pulling on you right now.” Mr. Jackson reached and grabbed a football from Gregory’s dresser and began tossing it a few feet in the air. “Notice how this ball falls back toward the Earth each time I throw it up.”

Gregory raised an eyebrow and compressed his lips.

“The question you should ask,” Mr. Jackson explained to Gregory, “is, if as you say, there were no gravity in space, and the space station were orbiting around the Earth every couple hours, what keeps it from flying off into deep space? Why does it keep going in a circle?”

(To be continued)