When space veterans talk about seeing world's first artificial satellite on Oct. 4, 1957, the tale usually gets better with decades of retelling. Few people on Earth actually witnessed the small, shiny sphere that marked the opening shot in the space race.
The satellite itself was never brighter than magnitude 4 or 5 — on the edge of naked-eye visibility. Some instrument-equipped observers in America's "Moonwatch" program logged sightings of Sputnik, and a few private observers with binoculars and accurate visibility predictions spotted the tiny moving dot among the stars.
However, what most people — including myself — observed was Sputnik's massive carrier rocket. This boxcar-sized behemoth flashed as it tumbled end over end. During the rocket's three-month space voyage, it shone among the brightest stars in the night sky.
The first Sputnik presented an entirely different visual apparition to those who witnessed it actually taking off. Workers at the launch site near the Aral Sea in central Asia watched it soar into space during its near-midnight launch. For technical reasons that only later became obvious, what these observers saw convinced them for several desperate minutes that the launch was failing.
During the previous months' test flights of the R-7 ("Semyorka") intercontinental ballistic missile, ground observers had seen the multiflamed rocket soar high into the sky, then arc to the northeast as it continued to climb. The trajectory was "lofted," thrown at a high angle to peak about 620 miles (1,000 kilometers) high, halfway to its impact point.
On later flights, which worked, the engines faded with growing distance while still high in the sky, probably halfway to the zenith. But for earlier flights, seared into the fresh memories of the witnesses, the light in the sky flared and then fell back toward the horizon as the engines exploded and burned.
Just as with shot-down warplanes of the still-recent Second World War, of which most space workers were veterans, a flame falling toward the horizon was the sign of a doomed craft.
On Oct. 4, as the Sputnik rocket climbed higher and higher, these observers watched, wondered and then worried as its angular motion across the sky soon took a frightening downward turn.
According to witnesses who later recalled the event, the handful of trajectory specialists watching from an observation point a mile away tried to console their distraught colleagues and clarify what they were actually seeing. An orbital flight was not lofted to a peak altitude, as the surface-to-surface launches had been, so of course the motion across the sky would be very different.
Instead, in order to achieve orbital velocity as efficiently as possible, the rocket would change to a horizontal flight path as soon as it was above most of the atmosphere. Once it gained enough velocity in that lower orbit, it would successfully "fall over the receding horizon" and remain in Earth orbit.
Only rockets aimed to fall back to Earth, as the long-range bombardment missiles were, counterintuitively appear to fade away and disappear as they soar upward. Conversely, in the new "common sense" of the minutes-old space age, rockets not intended to fall back to Earth appear, instead, to head downward toward the far horizon.
The impression that Sputnik was falling back to Earth was an illusion of perspective. Ground observers saw it moving away from them horizontally in its 296-second thrust into orbit. True, the Sputnik rocket's dimming flame was getting lower in the observers' sky, but this was due only to the growing distance — the rocket was not losing altitude, but was concentrating almost entirely on gaining speed.
The launch was entirely successful. And with more experience, the view that had so anguished the eyewitnesses to the birth of Earth's first artificial satellite came to be understood as a "normal" feature of spaceflight. Spaceflight had begun its immense influence, changing human perspective on so many things.
James Oberg, space analyst for NBC News, spent 22 years at the Johnson Space Center as a Mission Control operator and an orbital designer. He is the author of several books about the U.S. and Soviet space programs, including "Red Star in Orbit" and "Star-Crossed Orbits."
A shorter version of this article appears in the October 2007 issue of Astronomy magazine.