Peter, James, and John, in the holy mount: We were eyewitnesses of his majesty

 

 

 For we have not followed cunningly devised fables, when we made known unto you the power and coming of our Lord Jesus Christ, but were eyewitnesses of his majesty. For he received from God the Father honour and glory, when there came such a voice to him from the excellent glory, This is my beloved Son, in whom I am well pleased. And this voice which came from heaven we heard, when we were with him in the holy mount. 

 

-- II Peter 1:16ff.

And he was transfigured before them: Jesus as Brocken spectre

And after six days Jesus taketh Peter, James, and John his brother, and bringeth them up into an high mountain apart, And was transfigured before them: and his face did shine as the sun, and his raiment was white as the light.

-- Matthew 17:1f.

And after six days Jesus taketh with him Peter, and James, and John, and leadeth them up into an high mountain apart by themselves: and he was transfigured before them.And his raiment became shining, exceeding white as snow; so as no fuller on earth can white them.

-- Mark 9:2f.

And it came to pass about an eight days after these sayings, he took Peter and John and James, and went up into a mountain to pray. And as he prayed, the fashion of his countenance was altered, and his raiment was white and glistering.

-- Luke 9:28f.

A Brocken spectre (German Brockengespenst), also called Brocken bow or mountain spectre, is the apparently enormous and magnified shadow of an observer, cast upon the upper surfaces of clouds opposite the sun. The phenomenon can appear on any misty mountainside or cloud bank, even when seen from an aeroplane, but the frequent fogs and low-altitude accessibility of the Brocken, a peak in the Harz Mountains in Germany, have created a local legend from which the phenomenon draws its name. The Brocken spectre was observed and described by Johann Silberschlag in 1780, and has since been recorded often in literature about the region. 

More here.

Transfigured six days after these sayings, or eight days?

Verily I say unto you, There be some standing here, which shall not taste of death, till they see the Son of man coming in his kingdom. And after six days Jesus taketh Peter, James, and John his brother, and bringeth them up into an high mountain apart,

-- Matthew 16:28f.

And he said unto them, Verily I say unto you, That there be some of them that stand here, which shall not taste of death, till they have seen the kingdom of God come with power. And after six days Jesus taketh with him Peter, and James, and John, and leadeth them up into an high mountain apart by themselves: and he was transfigured before them.

-- Mark 9:1f.

But I tell you of a truth, there be some standing here, which shall not taste of death, till they see the kingdom of God. And it came to pass about an eight days after these sayings, he took Peter and John and James, and went up into a mountain to pray.

-- Luke 9:27f.