13
Marlene watched her mother owlishly. She was careful to keep her expression flat and meaningless, but within herself she was both pleased and surprised. Her mother was finally telling her of the events involving her father and Commissioner Pitt. She was being treated as a grown-up.
Marlene said, 'I would have checked Nemesis' motions regardless of what Commissioner Pitt said, Mother, but I see you didn't. Your guilt makes it plain.'
Insigna said, 'I can't get used to the notion that I wear my guilt like a label on my forehead.'
'No-one hides their feelings,' said Marlene. 'If you really watch, you can always tell.'
(Others couldn't. Marlene had learned that only slowly, and with difficulty. People just didn't look, they didn't sense, they didn't care. They didn't watch faces, and bodies, and sounds, and attitudes, and little nervous habits.)
'You shouldn't really watch like that, Marlene,' said Insigna, as though their thoughts had taken parallel paths. She put her arm around the girl's shoulder to prevent her words from sounding like a scolding. 'People get nervous when those large dark eyes of yours fix on them soulfully. Respect people's privacy.'
'Yes, Mother,' said Marlene, noting without effort that her mother was trying to protect herself. She was nervous about herself, wondering how much she gave away at each moment.
Then Marlene said, 'How is it that despite all your guilty feelings about the Solar System, you did nothing?'
'A number of reasons, Molly.'
(Not 'Molly,' thought Marlene with anguish. Marlene! Marlene! Marlene! Three syllables. Accent on the second. Grown up!)
'Like what reasons?' asked Marlene sulkily. (Couldn't her mother detect the wave of hostility that swept over Marlene each time a kid name was used? Surely it twisted her face, smoldered her eyes, convulsed her lips. Why didn't people notice? Why didn't people look?)
'For one thing, Janus Pitt was very convincing. However odd the points he makes, however hostile you feel toward them at the time, he always makes you see that he has good reasons for his viewpoints.'
'If that's true, Mother, he's awfully dangerous.'
Insigna seemed to break away from her thoughts to glance curiously at her daughter. 'Why do you say that?'
'Every point of view can have good reasons behind it. If someone can seize those reasons quickly, and present them convincingly, he can argue anyone into anything, and that's dangerous.'
'Janus Pitt has those abilities, I'll admit. I'm surprised you understand these things.'
(Marlene thought: Because I'm only fifteen, and you're used to thinking I'm a child.)
Aloud, she said, 'You learn a lot watching people.'
'Yes, but remember what I told you. Control the watching.'
(Never.) 'So Mr Pitt persuaded you.'
'He made me see there'd be no harm in waiting awhile.'
'And you weren't even curious to study Nemesis and see exactly where it was going? You would have to be.'
'I was, but it's not as easy as you think. The Observatory is in constant use. You have to wait your turn to use the instruments. Even if I'm the head, I can't use them freely. Then, too, when someone does use them, there no secret about it. We know what it's being used for and why. There was very little chance I would be able to develop a really detailed spectrum of Nemesis and of the Sun, or to use the Observatory computer on the necessary calculations, without people knowing at once what I was doing. I suspect that Pitt had a few people in the Observatory watching me, too. If I had stepped out of line, he would have known at once.'
'He couldn't do anything to you about it, could he?'
'He couldn't have me shot for treason if that's what you mean - not that he'd dream of doing such a thing - but he could relieve me of my Observatory duties and put me to work in the farms. I wouldn't want that. It wasn't long after I'd had that little talk with Pitt that we discovered that Nemesis had a planet - or a companion star. To this day, we're not sure what to call it. They were only separated by a distance of four million kilometers and the companion object didn't radiate in visible light at all.'
'You're talking about Megas, aren't you, Mother?'
'Yes, I am. It's an old word meaning "big" and, for a planet, it's very big, considerably bigger than the Solar System's largest planet, Jupiter. But it's very small for a star. Some think of Megas as a brown dwarf.' She broke off and eyed her daughter narrowly, as though suddenly uncertain as to her capacity to absorb matters. 'Do you know what a brown dwarf is, Molly?'
'Marlene is my name, Mother.'
Insigna flushed slightly. 'Yes. I'm sorry if I forget now and then. I can't help it, you know. I had a very dear little girl once whose name was Molly.'
'I know. And next time I'm six, you can call me Molly all you want.'
Insigna laughed. 'Do you know what a brown dwarf is, Marlene?'
'Yes, I do, Mother. A brown dwarf is a small starlike body, with too little mass to develop the temperatures and pressures to bring about hydrogen fusion in its interior, but enough mass to bring about secondary reactions that keep it warm.'
'That's right. Not bad. Megas is on the borderline. It's either a very warm planet or a very dim brown dwarf. It gives off no visible light, but emits richly in the infrared. It's not quite like anything we've ever studied. It was the first extrasolar planetary body - that is, the first planet outside the Solar System - that we have been able to study in detail, and the Observatory was totally immersed in it. I wouldn't have had a chance to work on Nemesis' motion even if I had wanted to, and, to tell you the truth, I forgot about it for a time. I was as interested in Megas as everyone else was, you see?'
'Um,' said Marlene.
'It turned out it was the only sizable planetary body circling Nemesis, but it was enough. It was five times the mass-'
'I know, Mother. It's five times the mass of Jupiter, and one thirtieth the mass of Nemesis. The computer taught me that long ago.'
'Of course, dear. And it's no more habitable than Jupiter is; less, if anything. That was disappointing at first, even though we didn't really expect to find a habitable planet circling a red dwarf star. If a planet were close enough to a star like Nemesis to keep water liquid, tidal influences would force it to face one side to Nemesis at all times.'
'Isn't that what Megas does, Mother? I mean, one side always faces Nemesis?'
'Yes, it does. That means it has a warm side and cold side, with the warm side quite warm. It would be at red heat, if it weren't that the circulation of its dense atmosphere tends to equalize temperatures somewhat. Because of this and because of Megas' own inner warmth even the cold side is quite warm. There are many things about Megas that were unique in astronomical experience. And then we discovered that Megas had satellite or, if you want to consider Megas a very small star, it had a planet - Erythro.'
'Which Rotor orbits, I know. But, Mother, it's been over eleven years since there was all that fuss about Megas and Erythro. In all that time, haven't you managed to sneak a look at the spectra of Nemesis and the Sun? Haven't you done a little figuring?'
'Well-'
Marlene said hastily, 'I know you have.'
'By my expression?'
'By everything about you.'
'You can be a very uncomfortable person to have around, Marlene. Yes, I have.'
'And?'
'Yes, it's heading for the Solar System.'
There was a pause. Then Marlene said in a low voice. 'Is it going to hit?'
'No, as far as my figures are concerned. I'm quite sure it's not going to hit the Sun, or the Earth, or any significant part of the Solar System, for that matter. But it doesn't have to, you see. Even if it misses, it will probably destroy the Earth.'
14
It was quite clear to Marlene that her mother did not like to talk about Earth's destruction, that there was internal friction inhibiting her discourse, that if she were left to herself, she would stop talking. Her expression - the way she pulled away a little from Marlene, as though anxious to leave; the way she licked her lips very delicately, as though she were trying to remove the taste of her words - was clarity itself to Marlene.
But she did not want her mother to stop. She had to know more.
She said gently, 'If Nemesis misses, how will it destroy the Earth?'
'Let me try to explain. The Earth goes around the Sun, just as Rotor goes around Erythro. If all there were in the Solar System were the Earth and the Sun, then the Earth would go around in the same path almost eternally. I say "almost" because, as it turns, it radiates gravitational waves that bleed the Earth's momentum, and that causes it very, very slowly to spin into the Sun, We can ignore that.
'There are other complicating factors because Earth isn't alone. The Moon, Mars, Venus, Jupiter, every object in the neighborhood pulls at it. The pulls are very minor compared to that of the Sun, so Earth remains in its orbit more or less. However, the minor pulls, which are shifting in direction and intensity in a complicated way, as the various objects themselves move, introduce minor changes in Earth's orbit. Earth moves in and out slightly, its axial tilt veers and changes its slant a bit, the eccentricity alters somewhat, and so on.
'It can be shown - it has been shown - that all these minor changes are cyclic. They don't progress in one direction, but move back and forth. What it amounts to is that the Earth, in its orbit about the Sun, quivers slightly in a dozen different ways. All the bodies in the Solar System quiver in this way. Earth's quiver doesn't prevent it from supporting life. At the worst, it may get an ice age or an ice disappearance and a rise and fall in sea level, but life has survived everything for well over three billion years.
'But now let us suppose Nemesis dashes by and misses, that it doesn't approach closer than a light-month or so. That would be less than a trillion kilometers. As it passes - and it would take a number of years to pass - it would give a gravitational push to the system. It would make the quivering worse, but then, when it was gone, the quivers would settle down again.'
Marlene said, 'You look as though you think it would be a lot worse than you make it sound. What's so bad about Nemesis giving the Solar System a little extra quiver - if it all settles down again afterward?'
'Well, will it settle down again in quite the same place? That's the problem. If Earth's equilibrium position is a little different - a little farther from the Sun, a little nearer, if its orbit is a little more eccentric or its axis a little more tilted, or less - how will that affect Earth's climate? Even a small change might make it an uninhabitable world.'
'Can't you calculate it out in advance?'
'No. Rotor isn't a good place to calculate from. It quivers, too, and a great deal. It would take considerable time and considerable calculation to deduce from my observations here exactly what path Nemesis is taking - and we just won't be sure till it gets considerably closer to the Solar System, long after I am dead.'
'So you can't tell exactly just how closely Nemesis will pass the Solar System.'
'It is almost impossible to calculate. The gravitational field of every nearby star within a dozen light-years has to be taken into account. After all, the tiniest uncalculated effect may build up to such a deviation in over two light-years as to make a passage that is calculated as a near-hit come out, actually, to be a total miss. Or vice versa.'
'Commissioner Pitt said everyone in the Solar System will be able to leave if they want to by the time Nemesis arrives. Is he right?'
'He might be. But how can one tell what will happen in five thousand years? What historical twists will take place and how that will affect matters. We can hope everyone will get off safely.'
'Even if they're not warned,' said Marlene, feeling rather diffident at pointing out an astronomical truism to her mother, 'they'll find out for themselves. They've got to. Nemesis will come closer and closer and it will be unmistakable after a while and they can calculate its path much more accurately as it comes closer.'
'But they will have that much less time to make their escape - if one is necessary.'
Marlene stared at her toes. She said, 'Mother, don't be angry with me. It seems to me as though you'd be unhappy even if everyone got away from the Solar System safely. Something else is wrong. Please tell me.'
Insigna said, 'I don't like the thought of everyone leaving Earth. Even if it is done in orderly fashion, with plenty of time and with no casualties to speak of, I still don't like the thought. I don't want Earth to be abandoned.'
'Suppose it must be.'
'Then it will be. I can bow to the inevitable, but I don't have to like it.'
'Are you sentimental about Earth? You studied there, didn't you?'
'I did my graduate work in astronomy there. I didn't like Earth, but that doesn't matter. It's the place where human beings originated. Do you know what I mean, Marlene? Even if I didn't think much of it when I was there, it's still the world where life developed over the eons. To me it's not only a world but an idea, an abstraction. I want it to exist for the sake of the past. I don't know if I can make that clear.'
Marlene said, 'Father was an Earthman.'
Insigna's lips tightened a bit. 'Yes, he was.'
'And he went back to Earth.'
'The records say he did. I suppose he did.'
'I'm half an Earthperson, then. Isn't that so?'
Insigna frowned. 'We're all Earthpeople, Marlene. My great-great grandparents lived on Earth all their lives. My great-grandmother was born on Earth. Everyone, without exception, is descended from Earthpeople. And not just human beings. Every speck of life on every Settlement, from a virus to a tree, is descended from Earth life.'
Marlene said, 'But only human beings know it. And some are closer than others. Do you think about Father, sometimes, even now?' Marlene looked up briefly at her mother's face and winced. 'It's none of my business. That's what you're going to tell me.'
That's the feeling I just had, but I don't have to be guided by my feelings. After all, you're his daughter. Yes, I think about him now and then.' She shrugged her shoulders slightly.
Insigna said, 'Do you think about him, Marlene?'
'I have nothing to think of. I don't remember him. I've never seen any holograms, or anything.'
'No, there was no point in-' Her voice trailed off.
'But when I was littler, I used to wonder why some fathers stayed with their children when the Leaving happened, and some fathers didn't. I thought that maybe the ones who left didn't like their children, and that Father didn't like me.'
Insigna stared at her daughter. 'You never told me that.'
'It was a private thought when I was little. When I got older, I knew that it was more complicated than that.'
'You should never have had to think so. It's not true. I would have assured you of that, if I had had the slightest idea-'
'You don't like to talk about those times, Mother. I understand.'
'I would have anyway, if I had known about that thought of yours; if I could read your face as you read mine. He did love you. He would have taken you with him if I had allowed it. It's my fault, really, that you two are separated.'
'His, too. He might have stayed with us.'
'Well, he might have, but now that the years have passed, I can see and understand his problems a little better than I could then. After all, I wasn't leaving home; my world was coming with me. I may be over two light-years from Earth, but I'm still at home on Rotor where I was born. Your father was different. He was born on Earth and not on Rotor, and I suppose he couldn't bear the thought of leaving Earth altogether, and for ever. I think about that now and then, also. I hate the thought of Earth being deserted. There must be several billion people there whose hearts would break to leave it.'
There was silence between them for a moment, then Marlene said, 'I wonder what Father is doing back on Earth right now.'
'How can we possibly tell, Marlene? Twenty trillion kilometers is a long, long way, and fourteen years is a long, long time.'
'Do you suppose he's still alive?'
'We can't even know that,' said Insigna. 'Life can be very short on Earth.' Then, as though suddenly aware she wasn't talking to herself, she said, 'I'm sure he's alive, Marlene. He was in excellent health when he left, and he's only just approaching fifty now.' Then softly, 'Do you miss him, Marlene?'
Marlene shook her head. 'You can't miss what you've never had.'
(But you had him, Mother, she thought. And you miss him.)
