Sputnik could, too, be seen by the naked eye. Satellites shine with either the moon or sun on them. You’d only see the rocket flare while it was putting the satellite into orbit. Then it separates from the satellite and, as it loses its orbit, eventually disintegrates in the atmosphere.
Thanks for your response.
I don’t know how to explain this to you any better, as you seem to have some misconceptions about the facts.
Notice that other posters have indicated that even the Russians stated that the satellite itself was not visible from Earth’s surface.
It was the Second Stage Booster, which was seen. And the moon reflects the sun’s light, which does not provide enough illumination to make objects visible from Earth.
There are other threads on this same subject (Sputnik) and they confirm what I stated.
Sputnik was only in orbit for a few weeks, even though some think it is still ‘up there’.
I hope you take enough time to research this subject so you will know the truth for yourself.