Christmas Eve, early morning darkness over the United States.  And over the moon, too, as Apollo 8, accelerated by lunar gravity to a speed of 5,758 mph, approaches its destination, flying tail first, the large bell of the Service Propulsion System (SPS) engine leading the way.  About the pass behind the edge of the unseen moon.  Houston calls one last time.  “You’re go all the way.”

Jim Lovell replies, “We’ll see you on the other side.”

At the precise moment has been calculated for LOS, loss of signal — if the spacecraft is on course to pass around and not about to crash upon the surface — is 68 hrs. 58 min. 4 sec. into the flight.  Right on the button, the com link goes dead.  LOS.

We’ll see you on the other side.   On the other side of the moon.  On the other side of human experience.  On the other side of history.  On the other side of time.  We’ll see you on the other side.

Seven minutes of darkness pass.  And then we see it — streaks of light like water, lunar sunrise flowing over the mountains of the moon below them.   “Oh, my God, look at that.”   We only have time for a glance.   In three minutes, the SPS engine will fire to pull us out of the darkness and into lunar orbit, a maneuver called LOI — Lunar Orbit Insertion   The big engine will fire for precisely 4 min. 6.9 sec.

Ignition and . . .

Four minutes to reduce our velocity to 3,643 miles per hours.   The longest four minutes of our lives.  LOI — another term added to the poetry of spaceflight.

And blocked by the bulk of the moon from the home planet. We won’t emerge from the back of the moon for another twenty minutes.

The sleeping earth waits for twenty minutes.  Then, Mission Control proclaims to the world, “We got it!  We’ve got it! — Apollo 8 in lunar orbit.”

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Ten orbits, two hours per orbit.  Twenty hours in lunar orbit spanning Christmas Eve into early Christmas morning.  Fifty years ago.  We remember.  The sight captured in the crew’s iconic photos of the blue planet over the desolation of the lunar surface.  We remember their reading from Genesis.  That comes towards the end of Christmas Eve, on their ninth orbit, after an exhausting day of photographing the surface, of trying to capture it all, of going without sleep, of trying to sleep.

Remember their voices as much as the words, their voices stretched wafer thin by the distance, heavy and liquid with fatigue, as if they’d walked every mile of every orbit through every crater. Remember the sight as well as the words, the TV image in that historic broadcast as Apollo 8 traveled toward the terminator, the line between day and night, and the shadows below them lengthened.   Remember the growing distance as they returned to darkness, a darkness from which they might never emerge.

We’ll see you on the other side.