Odds and Ends
Thank you so much Petrov
21 4, 3:00am
In fact, the situation was a bit different. Petrov was on duty on sattelite control, he monitored the data from infrared early warning sattelite that was aimed on US missile bases.
Suddenly, sattelite reported about six launches from US base. The normal procedure was to immediately report to upper echelons, but Petrov suspected that something is wrong, because just six "Minuteman" missiles simply could not inflict enough damage to work as effective first-strike attack. So, he asked the radar stations (which should detect the missiles as soon as they rise over the horizon), and they reported nothing. Optical sattelite, aimed at this area, also reported no engine flares, so Petrov became convinced that this is a false alarm and ordered to stand down.
Eventually, it was discovered that sattelite optics was aligned imperfectly, and bright solar rays, rfeltected from high-altitude clouds, accidently gave infrared signatures, which corresponded with missile launches.
P.S. And Petrov could not "set a counter strike in motion". He was only supposed to rely the data to higher echelons, who would make a decision about what to do next.