On June 3, 1965, Edward H. White, II, was the first American to "walk" in space. In the photograph I have of Mr. White drifting in space, the sun is a brilliant highlight on his face shield, and most of the direct light on his spacesuit is from the sun. The rest of the light is reflected sunlight from the earth -- earthshine, as it were. If the earth were farther away, say a million miles, the areas of his suit not directly lit by the sun would be as black as space itself. On that earthbound Christian day in June of 1965, the sunlit side of Mr. White's body was the daylight side of the temporary planet that he was, and the dark side was the night.

"Terminator" is the technical term for the fuzzy twilight zone that separates night from day on a moon or planet. From our earthbound vantage, the terminator of the moon is the region separating the day side of the moon from its night side. For the temporary moonlet that Mr. White was on June 3, 1965, night and day were separated by the thickness of a man's body. The original divine separation of day and night were compressed that day, by human beings, to a matter of inches.

In my photo of Mr. White in space, the terminator runs across the middle of his helmet, front to back, then down the left side of his chest, rippling over the zigs and zags of the folds in the fabric of his suit creating local horizons in the several terminators separating night from day on his legs, arms, feet and hands.

I became an engineer because I wanted to build rocketships and go into space. Actually, of course, we are all of us already in space, riding on this planet that orbits a star. To be more specific, I wanted to leave the earth and its mundane cycles of time, and the grave burden of its relentless hug. Another planet would have been nice to visit or live on, if it were small, or artificial, which would make the gravity less burdensome. And being located a billion miles north or south of the sun would be good, giving a view of the sun and the planets and nearly everything else.

The idea of living in an apartment on the hundredth floor of a building at the north pole of the moon is appealing. The south pole would be just as good, except that the earth would appear upside down from my living room or bedroom window -- upside down, that is, relative to our present maps of the earth.

Actually, a lunar polar penthouse with a hemispheric dome would give a view of the earth in an unchanging location just above the lunar horizon. With binoculars, the continents would be visible, and on the night side of the earth, so would the lights of New York, Chicago, Tokyo, Singapore, Bombay, Berlin, Paris, London, Johannesburg, Rio. The earth would make one complete rotation every 25 hours while staying in the same location on the local lunar horizon.

Every 28 days, the earth would go through its phases -- new earth, first quarter, half earth, three quarters, full, and then it would wane back to new with the sun right behind it. That's how the earth would look from the moon -- that's how it does look, were someone there to see it. But there's more to the picture than the changing earth over the same desolate lunar hills with the sun cycling across the horizon every 28 earth days.

On earth we are governed by two natural cycles, the daily one of light and dark, and the annual one of heat and cold. For someone living in space, even in an apartment on the poles of the moon, the divine separation of light from darkness would not apply -- or, simultaneously, it would be more immediate: When Mr. White was drifting in the sunlight in June of 1965, night and day were side by side on his body; he could see his own terminator.

The moon might be sufficiently small that, even from a sixth- floor vantage at the lunar north pole, the terminator might be readily visible, stretching to the horizon. Were you to look at the earth in half phase from one of the moon's poles, the lunar terminator would lie before you, lunar night to one side, day to the other.

On the moon, the "day" is 28 earth days long, and there are no seasons. In outer space, there are no cycles equivalent to day and night or to seasons. Someday, when human beings live permanently in space, their sense of time will be governed by artificial cycles rather than natural ones.

On earth we have 24 time zones, and only those people who live within a few hundred longitudinal kilometers of one another are synchronized within the same temporal cycles. Temporally, the earth is disunited; in space, though, when human societies stretch across hundreds of trillions of cubic kilometers, units of artificial time will have to be broadcast so that space civilization will be in sync -- awake in phase, asleep in phase, eating in phase. Everyone will live on the same time cycle -- even members of a different space societies and cultures.

For that portion of humanity that someday resides in space, the perception of time, with daily cycles of darkness and light and the annual cycles of seasons, will no longer exist. Nor will up and down exist, which means that concepts of hierarchy, and of goodness residing over evil, and all the other things that have evolved in a setting of gravity and earthly time cycles will no longer be part of on-going human experience.

Edward White achieved planetary-scale status in June of 1965. In January 1967, he died in an Apollo fire, along with Virgil Grissom and Roger Chaffee. Death is the price that pioneers will pay at the terminator of light and dark, night and day. The terminator between life and death is forever part of life's eternal growth into new places and spaces.