Junie said, “Back there, you threw an enormous barbell up in the air and caught it. How much did you say it weighed?”
I said, “Three hundred. That was my three-hundred-pound bell.”
“And does it actually weigh three hundred pounds?”
I said sure.
“I weigh only a little more than half that. Could you throw me, oh, fifteen feet into the air?”
I knew I could, but I said I did not know because I wanted to get my hands on her.
“But you might? Do you really think you might be able to, Hercules?”
I sort of raised up my shoulders the way you do and let them drop.
“We—if you failed to throw me high enough I would get a severe electric shock.” She looked scared.
I nodded really serious and said what we ought to do was try it first, right now. We would measure something that was fifteen feet, and then I would throw her up, and she could tell me if I got her up that high. So she pointed to the temporary wires they had strung up for the fair, and I wanted to know if those were the ones. She said no. They were not fifteen feet either. Ten or twelve maybe. But I said, “Okay, only do not reach out and grab them or you might get killed,” and she said okay.
So I got my hands around her, which was what I had been wanting to do, and lifted her up and sort of weighed her a couple times, moving her up and down, you know how you do, and then I spun around like for the hammer throw, and I heaved her maybe ten feet higher than those wires, and caught her easy when she came down. It made her really scared too, and I was sorry for that, but I got down on my knees and hugged her and I said, “There, there, there,” and pretty soon she stopped crying.
Then I said, “Was that high enough?” And she said it was.
She was still shaky after that, so we went back inside and she sat with me while I waited for the next tip. That was when she showed me the pictures that Roy T. Laffer had taken up on the White Cow Moon and the pictures of the rock that he had brought back, a great big rock that did not hardly weigh anything. “He let a little boy take it to school for a science show,” Junie told me, “and afterward the science teacher threw it out. Mr. Laffer went to the school and tried to reclaim it the following day, but apparently it had been blown out of the Dumpster.”
I promised her I would keep an eye out for it.
“Thank you. But the point is its lightness. Do you know why the moon doesn’t fall into the Earth, Hercules?”
I said that if I was going to throw her around she ought to call me Sam, and she promised she would. Then she asked me again about the moon and I said, “Sure, I know that one. The moon beams hold it up.”
Junie did not laugh. “Really, Sam, it does. It falls exactly as a bullet falls to Earth.”
She went and got a broom to show me, holding it level. “Suppose that this were a rifle. If I pulled the trigger, the bullet would fly out of the barrel at a speed of three thousand feet per second or so.”
I said okay.
“Now say that you were to drop that weight over there at the very same moment that the rifle fired. Your weight would hit the ground at the same moment that the rifle bullet did.” She waited for me to argue with her, but I said okay again.
“Even though the bullet was flying along horizontally, it was also falling. What’s more, it was falling at virtually the same rate that your weight did. I’m sure you must know about artificial satellites, Sam.”
I said I did, because I felt like I could remember about them if I had a little more time, and besides, I had the feeling Junie would tell me anyhow.
“They orbit the Earth just as the moon does. So why doesn’t the bullet orbit it too?”
I said it probably hit a fence post or something.
She looked at me and sort of sucked on her lips, and looked again. “That may be a much better answer than you can possibly be aware of. But no. It doesn’t orbit Earth because it isn’t going fast enough. A sidereal month is about twenty-seven days, and the moon is two hundred and forty thousand miles away, on average. So if its orbit were circular—that isn’t quite true, but I’m trying to make this as simple as I can—the moon would be traveling at about three thousand, five hundred feet a second. Not much faster than our rifle bullet, in other words.”
I could see she wanted me to nod, so I did.
“The moon can travel that slowly.” “Slowly” is what she said. Junie is always saying crazy stuff like that. “Because it’s so far away. It would have to fall two hundred and forty thousand miles before it could hit the Earth. But the bullet has to fall only about three feet. Another way of putting it is that the closer a satellite is, the faster it must move if it is to stay in orbit.”
I said that the bullet would have to go really fast, and Junie nodded. “It would have to go so fast that the curve of the Earth was falling away from it as rapidly as the bullet itself was falling toward the Earth. That’s what an orbit is, that combination of vertical and horizontal motions.”
Right then I do not think I was too clear on which one was which, but I nodded again.
Then Junie’s voice got sort of trembly. “Now suppose that you were to make a telephone call to your wife back in America,” is what she said. So I explained I did not have one, and after that she sounded a lot better.
“Well, if you were to call your family, your mother and father, your call would go through a communications satellite that circles the Earth once a day, so that it seems to us that it is always in the same place. It can do that because it’s a good deal lower and going a great deal faster.”
Then she got out a pen and a little notepad and showed me how fast the bullet would have to go to stay in orbit just whizzing around the world over and over until it hit something. I do not remember how you do it, or what the answer was except that it was about a jillion. Junie said anything like that would make a terrible bang all the time if it was in our air instead of up in space where stuff like that is supposed to be. Well, about then is when the
