“Now add the raisins,” said Samantha.

Lily upended the bag of raisins into the porcelain bowl, on top of the tangled lump of dough. A few landed on the wooden work bench and Samantha scooped them up in her hands. She dumped them into the bowl with the others.

“Okay, now mix them in.”

Her face fixed with an expression of stern concentration, the girl reached in with hands already white with milky flour. She plunged her pudgy fingers into the dough and began kneading. Behind them, the television muttered away to itself as a minor celebrity told whoever was interested how the recent satellite chaos was still affecting food and fuel prices. Both mother and daughter ignored it.

“That should do, I think,” said Samantha after a minute or two. “Now take the dough out of the bowl and put it on the table there.”

“And now we roll it flat!” said Lily with delight.

“Well, first we’ve got to separate it out into biscuit sized pieces. Pull a piece off, about as big as your hand.”

The little girl did so. “Good. Put it on the table there. Now keep pulling bits off until you've used it all up. Roll them up into circles of dough, then flatten them out. They need to be about a centimetre thick. Do you know what a centimetre is?”

“About this much,” said the girl, holding up a thumb and forefinger. “Do we use the roller?”

“No, just pat them flat with your hands.”

The little girl did so while her mother watched with delight. She had hopes that Lily would be an astronomer one day, following in her footsteps in the exploration of the cosmos. Something scientific anyway. Maybe, as she grew older, she would decide that her heart lay somewhere else. Biochemistry perhaps, or physics, but whatever it was, it would be a scientific career. She would be one of the great minds of her generation and her discoveries would take the world by storm. Until then, though, she was a little girl, and teaching your little girl how to cook biscuits was one of the great rites of passage, one of those landmark events of growing up, like the first day of school or having her measured for her first bra.

Samantha drank in the moment, therefore, so she would remember it when Lily was all grown up with a husband and children of her own. She would be going about her day, doing something routine and boring, and something would happen to trigger the memory. Seeing someone dipping a biscuit in their tea, perhaps, or hearing someone talking about their own little girl. She would pause for a moment to remember this moment and she would smile as she remembered her little girl patting the lumps of dough flat with her pudgy, flour covered hands. Then she would put the memory away until next time as she went back to whatever it was she had been doing.

So entranced was she with the scene playing out in front of her that it took her a moment to realise that the voice coming from the television had changed. The minor celebrity had gone and had been replaced by a news announcer saying something in a grim, serious voice. Something must have happened, she thought, but she paid it little attention. There were a number of ongoing stories in the news at the moment, from the Prime Minister desperate to remain in power by winning a crucial vote in parliament to the coastguard searching for a soap opera star whose light aircraft had vanished during a routine flight. Whatever it was, it would be on the main news tonight. She would pay it proper attention then.

Then the news announcer said “The moon” and both mother and daughter snapped their heads around at the exact same moment, black hair flying out in twin glossy fans. “Members of the public are warned not to look directly at the moon during the event,” the announcer continued. “Anyone wishing to watch should do so the same way as they would a solar eclipse, perhaps by looking through a piece of smoked glass.”

“What's he talking about, Mummy?” asked Lily.

“Hush, baby,” said Samantha, the biscuits forgotten, her whole attention now on the television.

The camera pulled out to reveal an expert looking man sitting in another chair beside the presenter. He had a neatly trimmed black heard and a pair of old fashioned spectacles that he kept taking off and polishing with a white handkerchief he kept in the breast pocket of his jacket. “So, what can we expect to see?” the presenter asked him.

“Well, Tom, as you said earlier, the energy released by the event will be enough to melt the entire leading hemisphere of the moon. Given time, the entire moon will probably melt, but rock is an excellent insulator of heat and it will take time for it to permeate through the entire bulk of the moon. Then, for several years at least, the entire moon will have been converted into a ball of molten rock. Molten all the way to the core. The Earth will have a second sun...”

“Gods!” cried Samantha in shock. “The second Scatter Cloud! It must be about to hit the moon! Phone! Call Neil Arndale!”

Before the phone could obey her command, though, it began playing ‘Moon Shadow’ by Cat Stevens. “Neil Arndale is calling,” the phone announced.

“Answer!” cried Samantha, and she ran across the room to grab her tablet, just in time as Neil's face appeared in it. “Sam!” he said, looking flustered and agitated. “Have you seen the news?”

“The second Scatter Cloud?”

Neil nodded. “They finished calculating the cloud’s exact course about an hour ago. The cloud’s dense core is heading directly for the moon. Everyone will be able to see it, so they rushed to issue a press release as soon as possible. I’m sorry we weren't able to tell you earlier...”

“That's okay,” said Samantha, glancing over at her brand new freezer, standing in the corner of the living room, the only place she had room for it. It was already stuffed full of frozen food, and there were more deliveries due to come. She would have to reorganise both her freezers to make room for it.

“How big and how fast?” she asked.

“We estimate that the moon will be hit by between one and two by ten to the eighteenth tons of matter at around thirty kilometres per second. Sam, that’s a total momentum about a quarter to a half of the momentum of the moon's orbit around the Earth...”

Samantha missed what he said next as everything went grey and she almost fainted. She clung to consciousness with an effort of willpower. “That...” She managed to croak out. “That means...”

“Mummy!” came Lilly’s voice from the garden. “Look at the moon!”

A spike of fear ran up Samantha's spine. She dropped the tablet onto the armchair and ran out into the garden to grab Lily’s arm and drag her back indoors. “Oow!” protested the girl in shock. “You hurt me Mummy!”

“Sorry, Baby. But you mustn't look! Like the man on the telly said. You'll hurt your eyes!” She ran out to the garage, resisting an almost overwhelming temptation to look up, and fetched the telescope she'd bought for her daughter. It was a twelve inch reflector, of the kind often described as a light bucket, that stood on a tripod and had a motor that allowed it to track an object across the sky. It also had a wireless link that allowed it to transmit images that could be seen on a tablet or a television set. She set it up in the middle of the garden, turned it on and pulled up the app on her phone that allowed her to control it. She told it to look at the moon, then went inside and told the television to show the images it was transmitting.

The entire eastern half of the full moon already looked subtly different. The features of the moon’s face, its dark seas and rayed craters, looked blurry, as if they were seeing it through a pane of frosted glass. Dust, she realised. A layer of dust was being raised from the moon's surface by the concussive impacts of thousands of cloud particles. They must be penetrating the moon's crust, she realised. They weren't exploding at the surface, as everyone had feared. Instead, they were penetrating miles below the surface before exploding, releasing the energy of their momentum as heat that turned the moon rock around it instantly to vapour. The shockwaves of the explosions then travelled up to the surface, where they shook up dust that had lain undisturbed for millions of years. In the vacuum, it would instantly fall back to the surface, but in the low gravity that would take time, and in the meantime it was obscuring their view of everything beneath it.

“Sam!” said Neil's voice from the tablet. “Sam! Are you there?”

“Right here, Neil,” said Samantha, picking it up again. “Sorry, got distracted there for a moment. What more can you tell me?”

“I'm sorry, but we’ve lost Copernicus. It must have been hit by a cloud particle. We lost contact with it forty five minutes ago.”

Samantha felt a pang of loss, almost as if she'd lost a family member. The data being sent back by the lunar satellite had been the foundation of her career for over ten years! She had enough data stockpiled, not even glanced at yet, to keep her busy for the rest of her life, and probably the next two generations of lunar astronomers as well, but it was still a blow. When she looked back at the image on the television screen, though, she realised that she should have expected it. There was no way that Copernicus could have survived that!

“Did we get any data from the impact?” she asked. Copernicus had had instruments that monitored and sampled space dust, and if, by some miracle, the cloud particle had registered on them...

“We're still studying the last few minutes of telemetry. All we’ve got so far, though, is confirmation of what we knew already, that the cloud particles are composed of some unknown, extremely dense form of matter. We’d probably have to actually get a cloud particle in the laboratory to learn more.”

“Could you actually do that? I mean, if some of them hit the earth?”

“Some have hit the earth. Not many, thank God, but there was a rash of a couple of hundred seismic disturbances across the western hemisphere a few hours ago. We think it was a mini cluster. There may be quite a few of them, all scattered around the main cluster. This one came in ahead of the main cluster, hit the Earth and took out several satellites. They evacuated the Harmony space station, it also took several hits. The astronauts are still on their way back down, so everyone's hoping none of the re-entry vehicles are hit. Listen, I've got to go, Nina’s on the blower. I'll get back to you as soon as I can, okay?”

“Okay. Thanks for calling me.”

“Are you coming in?”

“Not yet. I don't want to leave Lily right now. Maybe tomorrow.”

“Okay. See you then, maybe.” Neil severed the connection and Samantha turned back to the television.

“Look at that, Mummy!” said Lily, pointing to the image of the moon. Her hands were still covered with flour, Samantha saw. She'd wiped them on her clothes, with only partial success. Samantha thought about sending her to the bathroom to get cleaned up, but then she saw what had agitated her and she gasped in shock.

A number of bright spots had sprung up across the eastern limb of the moon. Samantha went to stand right in front of the television, close enough to be able to see the individual pixels of the image, but if anything it made the image less clear, not more. She knew what those bright spots had to be, though, and it made her long for a more powerful telescope. Her little light bucket just wasn't up to the job.

Then she laughed at her own stupidity. She was a world class astronomer! She had access to images sent back by the most powerful telescopes in the world, and they must all be focused on the moon at the moment. She went back to her tablet, called up the internet address of the Very Large Space Telescope Operations Control Centre in Guyana. She scrolled through the menus until she accessed the telescope’s live feed, entered her password, and a very much more highly magnified image of the moon appeared on her tablet.

She sent the image to her television. It showed a tiny part of the moon's surface, an area just a couple of dozen miles across. The blurring effect of the moon dust was even greater at this magnification, but the object under it was so bright that it was easy to see nonetheless. A huge geyser of molten rock. A blazing, incandescent fountain of fire shooting to what must have been a height of several miles in magnificent slow motion before falling again to form a pool around its base. A river of molten rock was already beginning to flow along a narrow canyon, growing longer even as she watched.

“What is it, Mummy?” asked Lily, fear in her voice. Samantha put an arm around her shoulders and felt her tiny body trembling with terror. It was a fear Samantha felt as well, although in her case it was because she understood the magnitude of what she was seeing and understood what it meant, the likely consequences for the world.

For Lily, though, it was the desecration of something she thought she knew that was scaring her. The moon had always been eternal, unchanging. You could memorise the names of features on its surface confident that they would always be there. It was the same moon that Julius Caesar had gazed up at, the same moon that the earliest cave men had seen shining in the night sky. Now, though, something tremendous was happening up there, something she was incapable of understanding. It was a fear that would soon be repeated in homes and families all over the world. A wave of superstitious terror that would sweep the planet. At the moment you needed a powerful telescope to really see what was happening, but that wouldn’t be true for much longer.

Samantha imagined all those cloud particles delivering their payloads of energy a hundred kilometres below the surface, where the density of the moon’s mantle finally became great enough to stop them. All that energy would be heating up those deep rocks, melting them, creating a vast sub-surface ocean of magma. As it heated it would expand and would look for any crack or fissure through which it could escape. The molten rock would almost certainly be way hotter than its melting point. It would be hot enough to melt the rock surrounding it and grow. The event was beyond doubt delivering enough energy that it would, eventually, melt the entire bulk of the moon, as the television expert had said, but that would soon be the very least of mankind’s problems.

A sudden desire came over her to go outside and look up at the moon with her own naked eyes. She fought it down with an effort, and instead brought back the image being sent by her light bucket telescope. The number of bright spots had increased noticeably. Each one was a geyser of magma, she knew. Hundreds of them now, and around each one a cloud of smoke was gathering. Volcanic gases. Carbon dioxide, various sulphur compounds. Maybe even some water vapour, if some of Copernicus’ latest findings were confirmed. Soon, they would cover the entire face of the moon, obscuring it from view for the first time since the Tycho impact, 109 million years before.

“There's nothing to be scared of, is there Mummy?” said Lily, the fear in her voice tearing at Samantha's heart. Her eyes stared up into hers, desperate for reassurance. Samantha's first instinct was to confirm her desperate plea, ease her daughter's fears, but events were now in motion that would have a devastating effect on the Earth and they would both have a better chance of coming through it if the little girl knew what to expect. If she could prepare herself for the ordeals to come.

Before she could say anything, though, the doorbell rang. “Your neighbour, Mrs Gunderson, is hat the door,” said the house computer in its Parker voice, a voice Samantha suddenly hated with a violent passion. Of course. She should have expected this. Everyone in her street knew she was a moon astronomer. Probably people for miles around. They would all be coming here, to hear her expert opinion on what was happening. There would probably be a television crew on her doorstep before long. She stared at the freezer in the corner of the room. If she let them in, they would see it and know she'd been stockpiling food. They would know she'd known something was coming and hadn't told them. How would they react? Even if they didn't react badly here and now, they would remember she had food when everything began going to hell. They would storm her house, steal her stash...

She ran upstairs to the bathroom and grabbed a bed sheet, then ran back down again. She spread the sheet over the freezer, hiding it from view, and grabbed a few ornaments from around the house to place on it while Lily watched with puzzlement. Then she unplugged the freezer. The tell tale humming noise stopped. Now it looked like an ordinary chest of drawers, probably containing clothes or a selection of board games and covered because it was a hideously ugly family heirloom. Hopefully they wouldn’t even question it, and so long as she kept the door closed the food inside should stay frozen for several hours. She would have to get rid of her guests before then.

She took a deep breath to steady her nerves, then went to answer the door. Mrs Gunderson had been joined by Mrs Mosley from further along the street, as well as Mister Hillier, a retired widower who lived with a fifteen year old golden retriever. He didn't have the dog with him, for which she was grateful, but there were curtains twitching all the way up and down the street and she knew it was only a matter of time before the small crowd outside her house grew. Best to get them inside, then, she decided, before it became a big crowd.

She barely had the door open, though, before the questions began. “What's happening?” demanded Mrs Gunderson, her eyes wide and staring. “What's happening to the moon?” They were all alternating their attention between her and the late evening sky. The moon was still low, and currently hidden from sight by the houses lining the street, but they looked anyway.

“You'd better come inside,” said Samantha reluctantly. Crowds tended to grow, and if she kept them on the doorstep other neighbours were likely to join them. The more of them there were, the longer it would take to get rid of them. She stood aside, therefore and the three of them hurried past her as if to get out of a heavy downpour. It occurred to get that, in those places where the sky was covered with clouds, there might still be people who didn't know that anything was happening, and she envied them their blissful ignorance.

She closed the door behind them. “You remember the Scatter Cloud?” she said. They nodded vigorously. “Well, there’s another one. A bigger one, and it’s hit the moon.”

“So there's no danger to us, then?” said Mister Hillier. “I mean, the moon gets hit by asteroids all the time, right? I saw it on one of the science channels.”

All they wanted was reassurance, Samantha realised. They wanted her to tell them there was no danger, that there would be nothing but an impressive light show following which everything would go back to normal. She saw it in their eyes as they stared hopefully at her. The fear, the uncertainty, the silent pleading for their hopes to be confirmed. She wished she could give them what they wanted.

“I’m afraid the danger is very real,” she said. “The fact is that we're seeing an event unparalleled in its size and importance since the early days of the solar system. You should all go home and make whatever preparations you can for a long period of chaos and uncertainty. Go to the shops and buy up as much food as you can before the shelves go empty. Also bottled water, medical supplies. It’s very likely that we're going to be thrown back on our own resources before long. The government and the authorities are going to be too busy trying to hold society together to look after individuals.”

They stared at her in something like shocked betrayal. That wasn't what she was supposed to say! “You’re joking, right?” said Mrs Gunderson. “You make it sound like the end of the world!”

“It won't be the end of the world,” said Samantha, “but the world is going to change out of all recognition. It's the nature of the impact, you see. If the moon had been hit by a single, solid mass, it would have been shattered and then it would have been the end, but the moon is being hit by a cloud of millions of tiny objects. Was being hit, I should say. What's left of the cloud has almost certainly moved past the moon by now. The remaining cloud particles will have been scattered all over the place by the moon's gravity. Some of them will probably hit the Earth. Probably not enough to do us any real harm, except locally...”

“Why didn't we get any warning of this?” demanded Mrs Mosley. “Why didn't they see it coming?”

“The cloud’s invisible. They knew it would be passing close to the Earth, but there was a good chance it would just pass us by. They didn't want to alarm people unnecessarily. There was every chance that the cloud would just pass us by and then head on, out of the solar system. Forever.”

“But it didn't!” accused Mrs Mosley.

“No, it didn't. We got unlucky. It wasn't anyone’s fault. No-one could have foreseen this...” She glanced over at the new freezer, then tore her eyes away before someone followed her gaze.

“So what happens now?” asked Mister Hillier. “So the moon gets pummelled. How does that affect us?”

“The impact...” The magnitude of what she was trying to say was so great that, for a moment, the words choked up in her throat. It was as if, if she didn't say it, it wouldn't happen. Except that it had happened. The impact of the second Scatter Cloud with the moon was over. All that was left now was the gradual realisation of what would happen next.

They’d been slowly drifting away from the front door towards the living room while they'd been talking, and Mrs Gunderson caught sight of the television. With a gasp of shock she pushed her way past the others to stand beside Lily, who stared up at her with bewilderment. Samantha suddenly hated these neighbours who'd intruded into her house. She wanted to be alone with Lily so she could make plans, decide how they were going to deal with the months and years ahead, until the chaos of the transition period was over and the world settled down into its new reality.

The western side of the full moon still looked completely normal, with the same dark seas and bright craters, but the eastern side was peppered with white, as if it had been dusted with flour. Each white spot was a circle of volcanic cloud emitted by a magma geyser below. There was no wind to blow it around, not yet anyway, and so it just hung there, shining in reflected sunlight as it spread into the surrounding vacuum.

“The moon will survive,” said Samantha. “It will suffer massive changes. It may even be completely melted, but it will survive. Eventually it will cool down again. The surface will solidify. New mountain ranges and valleys will form as the crust cools and shrinks. But...”

“But what?” demanded Mister Hillier. “What aren't you telling us?”

“It's the sheer size of the cloud, you see. The mass, I mean. And the speed it was travelling at. We can calculate its momentum, and it’s big, and it hit the moon in millions of tiny pieces instead on one big piece. Instead of a single giant impact, the moon received a gentle but insistent push, in a direction opposite to its motion around the Earth.”

“Which means?” asked Mister Hillier, his alarm growing.

“Which means,” said Samantha, “that the moon's orbit around the earth will have changed.”