Lucky thought: At least things are breaking fast.

He had been on Mercury only an hour. He had had scarcely time to do more than see his ship, the Shooting Starr, safely stowed in the underground hangar. He had met only the technicians who had handled the landing red tape and seen to his ship.

Those technicians, that is, and Scott Mindes, engineer in charge of Project Light. It had been almost as though the young man had been lying in wait. Almost at once he had suggested a trip to the surface.

To see some of the sights, he had explained.

Lucky did not believe that, of course. The engineer's small-chinned face had been haunted with trouble, and his mouth twitched as he spoke. His eyes slid away from L'ucky's cool, level glance.

Yet Lucky agreed to visit the surface. As yet, all he knew of the troubles on Mercury was that they posed a ticklish problem for the Council of Science. He was willing to go along with Mindes and see where that led him.

As for Bigman Jones, he was always glad to follow Lucky anywhere and any time, for any reason and no reason.

But it was Bigman whose eyebrows lifted as all three were getting into their suits. He nodded almost unno-ticeably toward the holster attachment on Mindes's suit.

Lucky nodded calmly in return. He, too, had noticed that protruding from the holster was the butt of a heavy-caliber blaster.

The young engineer stepped out onto the surface of the planet first. Lucky Starr followed and Bigraan came last.

For the moment, they lost contact with one another in the nearly total darkness. Only the stars were visible, bright and hard in the cold airlessness.

Bigman recovered first. The gravity here on Mercury was almost exactly equal to that on his native Mars. The Martian nights were almost as dark. The stars in its night sky were almost as brilliant.

His treble voice sounded brightly in the receivers of the others. "Hey, I'm beginning to make things out."

So was Lucky, and the fact puzzled him. Surely starlight could not be that bright. There was a faint, luminous haze that lay over the fumbled landscape and touched its sharp crags with a pale milkiness.

Lucky had seen something of the sort on the Moon during its two-week-long night. There, also, was the completely barren landscape, rough and broken. Never, in millions of years, either there on the Moon or here on Mercury, had there been the softening touch of wind or rain. The bare rock, colder than imagination could picture, lay without a touch of frost in a waterless world.

And in the Moon's night, too, there had been this milkiness. But there, over half the M'oon at least, there had been Earth-light. When Earth was full it shone with sixteen times the brightness of the full Moon as seen from Earth.

Here on Mercury, at the Solar Observatory at the North Pole, there was no near-by planet to account for the light.

"Is that starlight?" he finally asked, knowing it wasn't.

Scott Mindes said wearily, "That's the coronal glimmer."

"Great Galaxy," said Lucky with a light laugh. "The corona! Of course! I should have known!"

''Known what?" cried Bigman. "What's going on? Hey, Mindes, come on, give!"

Mindes said, "Turn around. You've got your back to it."

They all turned. Lucky whistled softly between his teeth; Bigman yelped with surprise. Mindes said nothing.

A section of the horizon was etched sharply against a pearly region of the sky. Every pointed irregularity of that part of the horizon was in keen focus. Above it, the sty was in a soft glow (fading with height) a third of the way to the zenith. The glow consisted of bright, curving streamers of pale light.

"That's the corona, Mr. Jones," said Mindes.

Even in his astonishment Bigman was not forgetful of his own conception of the proprieties. He growled, "Call me Bigman." Then he said, "You mean the corona around the Sun? I didn't think it was that big."

"It's a million miles deep or more," said Mindes, "and we're on Mercury, the planet closest to the Sun. We're only thirty million miles from the Sun right now. You're from Mars, aren't you?"

"Born and bred," said Bigman.

"Well, if you could see the Sun right now, you'd find it was thirty-six times as big as it is when seen from Mars, and so's the corona. And thirty-six times as bright too."

Lucky nodded. Sun and corona would be nine times as large as seen from Earth. And the corona could not be seen at all on Earth, except during periods of total eclipse.

Well, Mindes had not altogether lied. There were sights to be seen on Mercury. He tried to fill out the corona, to imagine the Sun it surrounded which was now hidden just below the horizon. It would be a majestic sight!

Mindes went on, an unmistakable bitterness in his voice. "They call this light 'the white ghost of the Sun.'"

Lucky said, "I like that. A rather good phrase."

"Rather good?" said Mindes savagely. "I don't think so. There's too much talk about ghosts on this planet. This planet's all jinx. Nothing ever goes right on it. The mines failed..." His voice trailed off.

Lucky thought: We'll let that simmer.

Aloud he said, "Where is this phenomenon we were to see, Mindes?"

"Oh yes. We'll have to walk a bit. Not far, considering the gravity, but watch your footing. We don't have roads here, and the coronal glimmer can be awfully confusing. I suggest the helmet lights."

He clicked his on as he spoke, and a shaft of light sprang out from above the face-plate, turning the ground into a rough patchwork of yellow and black. Two other lights flashed on, and the three figures moved forward on their thickly insulated boots. They made no sound in the vacuum, but each could sense the soft vibrations set up by each footfall in the air within their suits.

Mindes seemed to be brooding about the planet as he walked. He said in a low, tense voice, "I hate Mercury. I've been here six months, two Mermurian years, and I'm sick of it. I didn't think I'd be here more than six months to begin with, and here the time's up and nothing's done. Nothing. Everything about this place is wrong. It's the smallest planet. It's the closest to the Sun. Only one side faces the Sun. Over there"-and his arm swung in the direction of the corona's gleam- "is the Sun-side, where it gets hot enough in places to melt lead and boil sulfur. Over there in the other direction"-again his arm swung-"is the one planetary surface in the whole Solar System that never sees the Sun. Everything about the place is miserable."

He paused to jump over a shallow, six-foot-wide rift in the surface, a reminder of some eons-old Mercury-quake, perhaps, which could not heal over without wind and weather. He made the jump clumsily, the picture of an Earthman who, even on Mercury, stayed close to the artificial gravity of the Observatory Dome.

Bigman clicked his tongue disapprovingly at the sight. He and Lucky negotiated the jump with scarcely anything more than a lengthening of stride.

A quarter mile farther on, Mindes said abruptly, "We can see it from here, and just in time too."

He stopped, teetering forward, with arms outflung for balance. Bigman and Lucky halted with a small hop which kicked up a spurt of gravel.

Mindes's helmet flash went out. He was pointing. Lucky and Bigman put out their own lights and there, in the darkness, where Mindes had pointed, was a small, irregular splotch of white.

It was brilliant, a more burning sunshine than Lucky had ever seen on Earth.

"This is the best angle for seeing it," said Mindes. "It's the top of Black and White Mountain."

"Is that its name?" asked Bigman.

"That's right. You see why, don't you? It stands just far enough nightward of the Terminator... That's the boundary between the dark-side and the Sun-side."

"I know that," said Bigman indignantly. "You think I'm ignorant?"

"I'm just explaining. There's this little spot around the North Pole, and another around the South Pole, where the Terminator doesn't move much as Mercury circles the sun. Down at the Equator, now, the Terminator moves seven hundred miles in one direction for forty-four days and then seven hundred miles back in the next forty-four. Here it just moves half or mile or so altogether, which is why this is a good place for an observatory. The Sun and the stars stand still.

"Anyway, Black and White Mountain is just far enough away so that only the top half of it is lit up at most. Then, as the Sun creeps away, the light moves up the mountain slopes."

"And now," interposed Lucky, "only the peak is lit up."

"Only the top foot or two maybe, and that will be gone soon. It will be all dark for an Earth-day or two, and then the light starts coming back."

Even as he spoke the white splotch shrank to a dot that burned like a bright star.

The three men waited.

"Look away," advised Mindes, "so that your eyes get accustomed to darkness."

And after slow minutes he said, "All right, look back."

Lucky and Bigman did so and for a while saw nothing.

And then it was as though the landscape had turned bloody. Or a piece of it had, at any rate. First there was just the sensation of redness. Then it could be made out, a rugged mountain climbing up to a peak. The peak was brightly red now, the red deepening and fading as the eye traveled downward until all was black.

"What is it?" asked Bigman.

"The Sun," said Mindes, "has sunk just low enough now so that, from the mountain peak, all that remains above the horizon is the corona and the prominences. The prominences are jets of hydrogen gas that lift thousand of miles above the Sun's surface, and they're a bright red in color. Their light is there all the time, but ordinary sunlight drowns it out."

Again Lucky nodded. The prominences were again something which on Earth could be seen only during a total eclipse or with special instruments, thanks to the atmosphere.

"In fact," added Mindes in a low voice, "they call this 'the red ghost of the Sun.' "

"That's two ghosts," said Lucky suddenly, "a white one and a red one. Is it because of the ghosts that you carry a blaster, Mr. Mindes?"

Mindes shouted, "What?" Then, wildly, "What are you talking about?"

"I'm saying," said Lucky, "that it's time you told us why you really brought us out here. Not just for the sights, I'm sure, or you wouldn't carry a blaster on an empty, desolate planet."

It took a while for Mindes to answer. When he did, he said, "You're David Starr, aren't you?"

"That's right," said Lucky patiently.

"You're a member of the Council of Science. You're the man they call Lucky Starr."

Members of the Council of Science shunned publicity, and it was with a certain reluctance that Lucky said again, "That's right."

"Then I'm not wrong. You're one of their ace investigators, and you're here to investigate Project Light."

Lucky's lips thinned as they pressed together. He would much rather that were not so easily known. He said, "Maybe that's true, maybe it isn't. Why did you bring me here?"

"I know it's true, and I brought you here"-Mindes was panting-"to tell you the truth before the others could fill you-full of-lies."

"About what?"

"About the failures that have been haunting-I hate that word-the failures in Project Light."

"But you might have told me what you wanted to back at the Dome. Why bring me here?"

"For two reasons," said the engineer. His breathing continued rapid and difficult. "In the first place, they all think it's my fault. They think I can't pull the project through, that I'm wasting tax money. I wanted to get you away from them. Understand? I wanted to keep you from listening to them first."

"Why should they think it's your fault?"

"They think I'm too young."

"How old are you?"

"Twenty-two."

Lucky Starr, who wasn't very much older, said, "And your second reason?"

"I wanted you to get the feeling of Mercury. I wanted you to absorb the-the-- " He fell silent.

Lucky's suited figure stood straight and tall on Mercury's forbidding surface, and the metal of one shoulder caught and reflected the milky light of the corona, "the white ghost of the Sun."

He said, "Very well, Mindes, suppose I accept your statement that you are not responsible for failures in the project. Who is?"

The engineer's voice was a vague mutter at first. It coalesced gradually into words. "I don't know- At least... "

"I don't understand you," said Lucky.

"Look," said Mindes desperately, "I've investigated. I spent waking and sleeping periods trying to pinpoint the blame. I watched everybody's movements. I noted times when accidents took place, when there were breaks in the cables or when conversion plates were smashed. And one thing I'm sure of-- "

"Which is?"

"That nobody at the Dome can be directly responsible. Nobody. There are only about fifty people in the Dome, fifty-two to be exact, and the last six times something has gone wrong I've been able to account for each one. Nobody was anywhere near the scenes of the accidents." His voice had gone high-pitched.

Lucky said, "Then how do you account for the accidents? Mercury-quakes? Action of the Sun?"

"Ghosts!" cried the engineer wildly, flinging his arms about. "There's a white ghost and a red ghost. You've seen those. But there are two-legged ghosts too. I've seen them, but will anyone believe me?" He was almost incoherent. "I tell you... I tell you... "

Bigman said, "Ghosts! Are you nuts?"

At once Mindes screamed, "You don't believe me either. But I'll prove it. I'll blast the ghost. I'll blast the fools who won't believe me. I'll blast everyone. Everyone!"

With a harsh screech of laughter he had drawn his blaster, and with frenzied speed, before Bigman could move to stop him, he had aimed it at Lucky at point-blank range and squeezed its trigger. Its invisible field of disruption lashed out...