He is an expert on Mercury. Not the element, though once when he was twelve he accidentally dropped a glass thermometer, the old kind, and he dumped the mercury from the sharp halves into a plastic cereal bowl. He was home sick that day, all alone in the house, and he watched the liquid metal slide around the curved plastic, slick and shiny, separating into beads and rejoining again, for a very long time.
When his mother came home she was angry, because of mercury poisoning. He didn't know much about mercury poisoning, but he knew better than to touch it. He just wanted to watch it move. It was unlike anything else in his life: different than water, different than metal, different than plastic or wood or paper.
His mother said they had to throw the bowl away.
His girlfriend had long dark hair and a thin white body dotted with tiny moles. Not really beautiful, but she studied physics, and she was used to being the most beautiful woman in the room. Often the only woman in the room.
He was not the kind of man who had girlfriends who were used to being the most beautiful woman in the room. Or girlfriends at all, really. This one approached him after a talk on orbital velocities and told him she was impressed by the questions he asked the speaker. He was used to hearing that. People said his mind worked in ways that theirs didn't. He wouldn't have called it genius. Other people just failed to notice the details.
When the most beautiful girl in the room asked him if he wanted to get coffee, he assumed that she probably just wanted to talk to him about her career or maybe about his work.
He is an expert on Mercury, but he is not an expert on other things. For instance, when she told him she was pregnant he cried a little. She seemed annoyed but he couldn't help it.
"It's not a big deal," she said. "We already know what we're going to do about it."
"It's just," he said, "it seems like relationships don't survive this kind of thing. Like maybe you'll say it's all fine, but then you'll get upset later and leave me."
"I won't," she said. "Does that sound like me?"
He said no, but he wasn't sure.
He wondered about her, that she wasn't more emotional. Weren't they supposed to be emotional about this kind of thing? He was kind of relieved when she started sobbing on the way home from the appointment, though she said it was just that she was tired and stressed.
People know so much about Mars and Venus, and so little about Mercury. It's small, for one thing, and can be seen in the sky just at dawn and twilight. It's there in the day sky, near to the sun, but you'll never see it. The sun, big and bright, overshadows the planet. Telescopes see only a crescent, no detail. Probes sent to Mercury get caught by the pull of the sun's gravity.
But there are things an expert can deduce about a planet, even without mapping by probes. In fact probes take away the challenge and make it all too easy. For instance, simply based on the size and density of the planet he knows that the core of Mercury is iron. He can approximate the rotation of the planet and even make assumptions about its atmosphere.
The ancient Greeks thought the planet Mercury was two stars, one visible at dawn, one at dusk.
The ancient Greeks also thought that life began not at conception, but at the first movement in the womb, or quickening. Quick as in alive, as in the quick and the dead, as in quicksilver.
He really wanted her to move in with him. It made sense that they would get married. They both wanted the same things: scientific achievement, careers in academia, each other.
The Romans said that Mercury mated with Venus and produced Cupid. Two planets mating; it would be bizarre, to say the least. But he could believe, when they were together, that they were entire worlds.
"Shouldn't you talk to someone?" he asked her one morning at breakfast. "About the thing?"
She seemed irritated that he'd brought it up again. "I talk to you," she said.
"But your girlfriends," he said. "Or your mom. Shouldn't you talk to them?"
"No," she said.
She stirred her coffee and licked her spoon before she answered. "I don't want them to think I'm a failure."
She had a Ph.D. in astrophysics, an excellent post-doctoral position, terrific prospects for the future. She had him, and he was going to marry her. He didn't understand.
"You don't understand," she said. "Would you tell your mom?"
"No," he said, but he thought that was different. His mother worried, that was all, and he wanted her to think the best things about his future wife.
Of course they had some problems, every couple does. Like she thought it was okay to leave dishes in the dishwasher for a full three days before turning it on, and he thought that was disgusting, and might actually contaminate the dishes permanently. And he was smarter than her in their chosen field, which seemed to occasionally irritate her. And one time he looked at another girl—he doesn't even really remember it—and she started crying; not, she said, because he looked, but because he was so obvious about it, stopping on the street and swiveling his head, and clearly not thinking about her feelings at all.
Still, when she said she wanted to end it because she just didn't see it going anywhere, he was completely taken by surprise. He reminded her what he'd said before. "I told you," he said. "I told you relationships couldn't survive that."
"Are you kidding? That was like, six months ago," she said. "This isn't about that. Don't make this about that." She was surprisingly upset. Finally she did say he could have handled it better. That led to a long discussion: why hadn't she told him at the time? Why couldn't he just be more sensitive and think about how she might be feeling? Why did women expect men to read their minds? Eventually she cried and told him he was fine, it really wasn't about that. So what then? What was it? What?
Finally she said she was just done, and she had never meant for it to be as serious as it was, and she couldn't think of a good reason, so she was just saying anything that came to mind.
His analysis of the atmospheric readings taken in Mariner 10's first flyby was groundbreaking, intuitive, genius, everyone said. He had just gotten back from an international conference on astrophysics, a conference at which older professors came up to him to ask questions and compliment him on his work. He felt, for the first time in his life, like he knew more than anyone in the world about the planet Mercury. But he didn't get a chance to celebrate; the next day, he had to take his girlfriend to the clinic.
They held hands in the waiting room, but they said he had to stay there during the appointment. She had to go through the door and into the patient area alone. He sat there with all the other pregnant women and wondered: how was it that he knew so much, more than anyone, about a small hot planet, millions of miles away and overshadowed by a massive sun, and yet he couldn't even begin to imagine what was going on behind that door?
She came out of the same door she went in.
"It was fine," she said. She smiled. "Ready to go?"
On Earth, the gas molecules in the atmosphere absorb and scatter blue light in all directions, making the sky appear blue. From the empty surface of Mercury the sun would appear suspended, alone, in a desolate black sky.