Gwen sighted along her arm. "Aye, I see them."
"Well, that's the handgrip. And that line of four stars at a right angle to them? That's the barrel. The third star in from its end is our nearest neighbor." Chornoi shrugged. "It doesn't really have a name—just a number on the star-charts. The soldiers call it 'The Girl Next Door.'"
"How far away is it?" Rod asked.
"Just under seven light-years."
"Dost mean…" Gwen swallowed. "… that the star I see now is not truly the star? That 'tis but light that hath left it seven years agone?"
"Right." Rod nodded with vigor. "We're not seeing it as it is, but as it was seven years ago. Very right, dear. For all we know, it could be blowing up right now—but we wouldn't find out about it for seven years." Secretly, he was impressed with the quickness of Gwen's understanding.
His wife just stared up into the night sky, lost in the immensity of the concept.
"And planets," Rod murmured, "swing around and around their sun in circles that are just a little bit egg-shaped."
Gwen whirled to stare at him in astonishment. "Nay— for surely the Sun doth go about the Earth! I do see it rise and go across the sky daily!"
Rod shook his head. "It just looks that way. It's the earth that's turning, really." He cranked with a finger. "Around and around, like a spinning top. Stop and think about it— if you're turning around and around, it looks as though Yorick, there, is turning around yow, when he's really standing still, doesn't it?"
Gwen gazed at Yorick, then slowly began to turn around in place. After two revolutions, she said, "'Tis so." She stopped and looked up at Rod. "Yet merely from looking, how can I tell whether 'tis he that's moving, or I?"
Rod's breath hissed in. He'd known Gwen was intelligent, but he was amazed by the quickness with which her mind darted on to the next question. He stared at her, astounded by her mental leap. Then he smiled weakly. "Well, you have to have other kinds of evidence, too, dear. For example, when we look through telesc… uh, closely at other planets, we can see their moons going around and around them. That explains why our own moon wanders the way it does—it's really revolving around us. Which makes it a pretty good bet that we're revolving around our sun, especially after we've found out that it's a heck of a lot bigger than any of its planets." He shrugged. "And the bigger it is, the harder it pulls."
She stared at him for a long moment, then said slowly, "And is it for that reason that we will have such great difficulty in leaving this 'planet?'"
Rod caught his breath, staring at her. Then he opened his mouth, breathing in, and finally said, "Yes. The planet pulls things to it, just as the sun pulls the planet toward itself."
"Then why doth the planet not fall into the sun?"
"Because it's going too fast. Like…" Inspiration hit. "Like you, when you're trying to catch Geoffrey. He goes flying past, and you grab him, but because he's going so fast, you can't pull him in against you. On the other hand, you're holding on tightly enough so that he can't get away, either, so he just swings around at the end of your arm. Now, imagine that he refuses to stop, and he just goes on swinging around and around you, forever. And it's that same kind of pull, like your pull on him, that attracts things to the planet. Of course, from where we're standing, that 'attracting' looks like 'falling.' We call the force 'gravity.' The planet pulls on the object—like this." He pulled her up against him, and wrapped his arms around her. "And it doesn't want to let the object go."
Gwen smiled, her lids drooping. "Doth the object, then, not also draw the planet?"
"You do learn fast, don't you? Yes, the object pulls, too, but its pull is very weak, because it's so small. You and I, now, aren't all that much different in size."
"Nay," she murmured, "we are well matched."
Rod was definitely losing interest in the lecture, but there were people watching. "Now. Your original question was, why is it so hard for the object to get away from the planet?"
She smiled up at him. "Wherefore should it wish to?"
"Can't think of a good reason, myself," Rod admitted, "but just for the sake of argument, let's assume it does. Go ahead and try."
"An thou dost wish it," she sighed, and pushed against him.
He loosened his arms a little, letting her move away a few inches. "See—you have to be able to push really hard to get away from me. And that's how people leave planets— in flying ships that can push really hard against the planet."
"They're called 'spaceships,' by the way," Yorick put in. "Don't let him baby-talk you, milady."
"I would not consider it," Gwen said, with some asperity.
"And the ship," Rod said, "has to push hard enough to go fast enough—that's called 'escape velocity.' And when you're up to escape velocity…" He let go, and she stumbled back. "… you escape. And that's how you get off the surface of a planet. See?"
"Indeed." She came back, straightening her hair, the gleam of battle in her eye. "Yet could we not build such 'velocity,' my lord? Thou and I, together?"
In spite of himself, Rod took a step back. It took him a second to realize she was talking about telekinesis. "Well…"
But Yorick was watching them with growing apprehension. "Uh, Major—milady—don't do anything rash!"
"It would be," Rod admitted. "We might be able to do it if we pooled our forces, darling—but there's another little problem." He coughed delicately and looked up at the stars. "You see, we're not the only thing that the planet's holding to itself. It's also holding the air that we breathe."
She stared, at a loss.
"About twenty miles up…" Rod pointed. "… you run out of atmosphere. It's just empty space, without any wind, not even a breath of fresh air—or a breath of anything, for that matter. That's why Chornoi said she'd seen a planet from space—because there wasn't any air there. Just empty space."
Slowly, Gwen lifted her eyes to the stars again. "So much blackness between them… Yet how can there be 'space,' as thou dost call it, without air to breathe? Is that not the 'space?'"
Rod shook his head. "Air is a substance, too, just like water—only lighter, not as dense. It covers the planet's whole surface, but only because gravity holds it there. The farther you are from a planet, the weaker the pull feels, until it can't even hold air anymore. And when that happens, when you've got space with nothing in it, we call that 'vacuum.' That means there's nothing to breathe, too, of course—so even if we could get out there, honey, we wouldn't last long."
Slowly, Gwen lowered her gaze to him again, but the stars stayed in her eyes. "'Tis wondrous," she breathed. "Nay, I shall trust thee in this, my lord. But I shall trust, also, that together, we may find a way."
Chornoi shook her head in exasperation. "Don't you know better than to put that much trust in a man?"
"Nay." Gwen turned to her with a smile, catching Rod's hand behind her back. "And I trust that I never shall."
It was nice to know that she felt so warm about it, especially since Rod was feeling a chill run down his back and spread out to envelop his rib cage. She had learned it all so quickly! Everything she'd heard, she'd understood instantly, or almost. And every single one of those concepts was totally alien to her culture. He was beginning to dread that she might be smarter than he was. It was one thing for him to understand her culture, but it was entirely another for her to understand his.
"Well, be that all as it may—space, vacuum, and escape," Chornoi grumbled, "but the here-and-now is that we need to look at this place by daylight, and you two have to be back in town before morning."