There was a tradition, that on the Day of Atonement, a scarlet thread would be tied to the horn of the scapegoat (and another around the throat of the other goat). Once the sins of the people had been laid on the head of the scapegoat, it was considered to be a sign that God had accepted the atonement if the thread on the scapegoat miraculously turned white (cf. Isa 1:18). This occurred not infrequently prior to Christ's ministry, and indeed every year (centuries beforehand) when one "Simon the Upright" was priest, but ceased altogether, says the Talmud, forty years before the destruction of the Temple, in 70 AD!

Is this a well known story, among Christians?

It's pretty remarkable, if true, and of course the Christian explanation is that the miracle ceased as a sign that in Christ the Day of Atonement was fulfilled - the two goats typifying penalty for sin and separation from sin, death and resurrection; the blood of the goat for the sin offering sprinkled in the earthly most holy place, but Christ's sin offering accepted in heaven itself. Pretty neat.

Other wierd happenings in the Temple were recorded as taking place forty years before its destruction: the enormous lintel stone broke and fell, the massive Temple doors swung open by themselves, and the central light of the golden candlestick was extinguished.

Now, does this forty year figure indicate that the crucifixion was in AD 30, or is forty just a round number? I don't know. AD 32 or 33 seems to better fit the Daniel 9 prophecy, (but I do believe it was on some Friday, Nisan 15).