The difference between Noah's Rainbow and the one around the Throne of God is, that Noah's is composed of the seven primary colors [red,orange,yellow,green,blue and purple]; while the one around the Throne of God is emerald.
The Rainbow is the sign of a Covenant based on the Sacrifice of Noah [Genesis 8:20-22], and
the Rainbow about the Throne of God is the sign of a Covenant based on the Sacrifice of Jesus Christ on the Cross.
In this world we only see half of the Rainbow, or the half of things.

In Heaven we shall see the whole of things.
The first mention in the Bible of a Rainbow is in Genesis 9:13-17.
            "I do set My Bow in the cloud, and it shall be for a token of a Covenant between Me and the Earth."
                   
                      A Covenant that God would not destroy this earth again by a Flood. It was only semi-circular, like the ones after a rain.

      The Rainbow Ezekiel and John saw around the Throne of God was circular.
There are two things in Ezekiel's vision that corresponds with John's vision of the 'Throne of God.' :

           First, that the form of the one who sat on
                    the Throne could not be clearly
                    recognized or described, but that it
                    was surrounded with Light, which
                    veiled the form or person; and
      Second, that there was a Rainbow round
                    about the Throne.
                   The person of God then, as He sits
                   upon His Throne, is veiled in a Glory
                   that can only be compared to the
                   shining of a gem.

One of the remarkable things about the Throne of God is, that it is surrounded by a 'Rainbow' that is emerald in color.
Ezekiel describing his vision of the Throne of God says, "Above the Firmament that was over their heads was the likeness of a Throne, as the appearance of a Sapphire Stone: and upon the likeness of the Throne was the likeness as the appearance of a Man above upon it.
And I saw as the color of Amber, as the appearance of fire round about within it, from the appearance of His loins even upward, and from the appearance of His loins even downward, I saw as it were the appearance of fire, and it had brightness round about.
As the appearance of the Bow that is in the cloud in the day of rain, so was the appearance of the brightness round about.
This was the appearance of the likeness of the Glory of the Lord."
Ezekiel 1:26-28
In Revelation 21:10-11, John is describing the New Jerusalem saying, that its light is the Glory of God.

             A light like unto a stone as a Jasper stone, clear as crystal.

     This corresponds with His declaration in 1 John 1:5, that God is Light.
The first thing John saw in Heaven was a Throne.

             


 




Some One sat on it, who looked like sparkling gems.

      The One on the Throne was none other than God Himself.
"And immediately I was in the spirit: and, behold a Throne was set in Heaven, and One sat on the Throne.
And He that sat was to look upon like Jasper and a Sardius stone: and there was a Rainbow round about the Throne, in sight like unto an Emerald.

And out of the Throne proceeded Lightnings and Thunderings and Voices; and there were Seven Lamps of Fire burning before the Throne, which are the Seven Spirits of God.
And before the Throne there was a Sea of Glass like unto Crystal."
Revelation 4:2-3, 5-6
The presence of the Holy Spirit in Heaven is evidence that the events that follow are to take place after the Church is gone, and the Church is not to go through the Tribulation.
This is evidence that the Church has been 'caught out' and is no longer on the earth, for when the Holy Spirit goes back to Heaven, He will take the Church with Him.
In none of the Epistles is the Holy Spirit referred along with the Father and the Son, except in 2 Corinthians 13:14, because He is viewed abiding on the earth with the Church, but here He is no longer on the earth but back in Heaven, and before the Throne.
The Church is 'caught out' at this time and place, we have in the description of the Throne, the statement that the Holy Spirit is back in Heaven.
As it was a Trumpet like voice that summoned John, so it will be a Trumpet call that will summon the Saints at the Rapture.
The "Rapture" of the Church is described in
1 Thessalonians 4:16-17.
         "For the Lord Himself shall descend from Heaven with a shout, with the voice of the archangel, and with the trump of God; and the dead in Christ shall rise first: then we which are alive and remain shall be caught up together with in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord."
John lived until ,in his vision, he saw the Return of the Lord.

         Its fulfilment is in John's being caught up in vision and beholding, before his death, what he would have witnessed and experienced if his life had been prolonged until Jesus came back.
After Peter's confession that Jesus was the Christ, the Son of the living God in Matthew 16:13-28, and Jesus had said that upon this rock [Peter's confession that He is the Christ, the Son of the living God] He would build His Church; then Jesus said to His Disciples,
"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."
In this "Rapture" of John, we have a type of the Rapture of the Church, and it is at this place in the Book of Revelation that the Rapture of the Church takes place.
Immediately after John was called to "come up hither", he was in the spirit: "and, behold, a Throne was set in Heaven, and ONE sat on the Throne."

          John's experience was similar to that of Paul, who was caught up into Paradise.

               Whether in the body or out of the body they are uncertain,

                      The difference between them was that while Paul heard words that he was forbidden to speak; John was told to "write in a book" the things he saw and heard, and send them to the Seven Churches.
John says that 'after this' after the vision of Christ in the middle of the Seven Candlesticks,
and His view of the history of the Churches
according to the messages given to the Seven Churches,
that brought him to the end of the Church Age;
he [John] looked and behold a door was opened to heaven,
and the same voice that spoke to him from the middle of the candlesticks,
which was the voice of Christ [Revelation 1:10-13],
said, "Come up hither and I will show the things which must be hereafter."
THE HEAVENLY DOOR   Revelation 4:1

"After this I looked, and, behold, a DOOR OPENED IN HEAVEN: and the first voice which I heard was as it were a trumpet talking with me; which said, Come up hither, and I will shew thee things which must be hereafter [after these]"

           The scene now changes from earth [Patmos] to Heaven.
Chapters four and five of Revelation introduces and prepares the prophetic action of the "Seals", "Trumpets" and "Vials".
The Church disappears from view at the end of the third chapter and isn't heard of again until the nineteenth chapter, where her marriage to the Lamb is announced.  Revelation 19:7-9

       The removal of the Church at the end of the third chapter opens the way for God to renew Himself with Israel.

                   From chapter three to the end of chapter nineteen is made up of symbols, the conclusive evidence that God is back on Jewish ground and that the last or "Seventieth Week" of  Daniel's "Seventy Weeks" is being fulfilled.
THE THINGS WHICH SHALL BE HEREAFTER

         The word translated "hereafter" would be better translated "after these things."

         The word "hereafter" permits a time of space, while the words
'after these things' refers to the things that shall immediately follow the completion of the Church Age.
Happy New Year 2013!