what will happen when the Messiah comes?

* The Sanhedrin will be re-established (Isaiah 1:26)
* Once he is King, leaders of other nations will look to him for guidance. (Isaiah 2:4)
* The whole world will worship the One God of Israel (Isaiah 2:17)
* He will be descended from King David (Isaiah 11:1) via King Solomon (1 Chron. 22:8-10)
* The Moshiach will be a man of this world, an observant Jew with "fear of God" (Isaiah 11:2)
*****In other words - this must all be accomplished in a human lifetime*****
* Evil and tyranny will not be able to stand before his leadership (Isaiah 11:4)
* Knowledge of God will fill the world (Isaiah 11:9)
* He will include and attract people from all cultures and nations (Isaiah 11:10)
* All Israelites will be returned to their homeland (Isaiah 11:12)
* Death will be swallowed up forever (Isaiah 25:8)
* There will be no more hunger or illness, and death will cease (Isaiah 25:8)
* All of the dead will rise again (Isaiah 26:19)
* The Jewish people will experience eternal joy and gladness (Isaiah 51:11)
* He will be a messenger of peace (Isaiah 52:7)
* Nations will end up recognizing the wrongs they did to Israel (Isaiah 52:13-53:5)
* The peoples of the world will turn to the Jews for spiritual guidance (Zechariah 8:23)
* The ruined cities of Israel will be restored (Ezekiel 16:55)
* Weapons of war will be destroyed (Ezekiel 39:9)
* The Temple will be rebuilt (Ezekiel 40) resuming many of the suspended mitzvot
* He will then perfect the entire world to serve God together (Zephaniah 3:9)
* Jews will know the Torah without Study (Jeremiah 31:33)
* He will give you all the desires of your heart (Psalms 37:4)
* He will take the barren land and make it abundant and fruitful (Isaiah 51:3, Amos 9:13-15, Ezekiel 36:29-30, Isaiah 11:6-9).
Thanks to Mark S and Plushy Bear

Jesus Was Accepted as the Messiah. The historical evidence found in the Gospels demonstrates that Jesus was indeed the Messiah. Persons in the first century, who were in position to question the witnesses and examine the evidence, accepted the historical information as authentic. They were so sure of its accuracy that they were willing to endure persecution and die on behalf of their faith based on that assured information. The historical Gospel records show that various individuals openly acknowledged that Jesus was the Christ, or Messiah. (Mt 16:16; Joh 1:41, 45, 49; 11:27) Jesus did not say they were incorrect, and on occasion he admitted being the Christ. (Mt 16:17; Joh 4:25, 26) Sometimes Jesus would not say pointedly that he was the Messiah; at times he directed others not to publicize it. (Mr 8:29, 30; 9:9; Joh 10:24, 25) Since Jesus was present where people could hear him and see his works, he wanted them to believe on the solid basis of this evidence, so that their faith would be founded on their own eyewitness view of the fulfillment of the Hebrew Scriptures. (Joh 5:36; 10:24, 25; compare Joh 4:41, 42.) Now the Gospel record of what Jesus was and did has been provided along with the Hebrew Scriptures, which supplied abundant information about what he would do, so that individuals may know and believe that Jesus is indeed the Messiah.—Joh 20:31

Here:

http://www.biblegateway.com/passage/?search=Rev%2019:11-Rev%2020:15&version=NIV

When the Messiah comes for the second time, the whole world will disappear in a flash. He will come with all his glory to judge the living and the dead. We will all be judged by this light...the immense power of His Love. Evil will burn and the righteous will be saved...those who are in between will suffer greatly before they will be accepted by God.

Nothing, because the Messiah ain't coming

And behold! the Messiah shall return to bring the good word to his people. That good word shall be: relax.

Show us the Messiah!

He'll probably say, "Dude, you guys are kind of undeserving. Give me a call when you've improved the world and become less selfish and greedy people, because right now none of you are worthy.

Look, it's complicated.
Something went wrong in some space journey.
There were many in those times.
1. The expel from garden of Eden. surely can't be on earth.
2. The Nephilim (Sons of God) who landed on earth and made us, by mating with women they found on earth.
3. All the events on Mount Sinai (fire and smoke) mosses was taken to other planets. He had done years learning, but when he came back it was 40 days only.
4. Jehoshua stationed the Sun and the Moon for hours in relative to earth. This could only be achieved by control from space.
And, more bizarre phenomena, which requires a lot of creativity to invent, unless evidenced.
The Space travel connected to the Messiah, is of Elijah the profit, who expects to bring the Messiah.
The bible tell us that a 1000 years will pass like a day. Again, one needs to be nuts to have such imagination that time can span and shrink (Einstein came a bit after, right)?
Anyway, this is an evidence of space travel, so,
Those who brought us here are not gods, and therefore not absolutely superior, and can make mistakes, and, can change decisions.
Even God destroyed the first world he made because he thought it was no good. Also in the flood story we see a disappointed god. How can God, as we conceive, doesn't know what's he doing?
So some possible scenario are:
1. The space travel carrying the Messiah, is delayed by few hours, which on earth will be equivalent to few hundreds of years.
2. The pilot was challenging a black hole and was sucked in.
3. There was a collision with an undetected object.
4. The messiah refuses to make the travel.
5. They lost the way.
6. They are having their own wars
7 They are watching us, and extend the game a bit longer till we rotten more.
8. They misinterpreted our progress, and afraid to risk an expedition landing the messiah here.
9 The concluded that anyway we will kill him in the first hour he land, so why bother.

So, before you can ask what will happen when he comes, you need to see if it is any relevant.

If? ok, he (they) will switch our brains to peace and generosity mode.
Yeah, their technology allows it.
They control what we are striving for- the secret of OUR life, but may not necessarily be the end of the chain.

revelation 19:19 and i saw the beast and the kings of the earth and their armies assembled to make war against Him who sat on the horse and against His army.and the beast was seized,and with him the false prophet who performed the signs in his presence,by which he deceived those who had received the mark of the beast and those who worshiped his image;these two were thrown alive into the lake of fire which burns with brimstone.and the rest were killed with the sword which came from the mouth of Him who sat on the horse,and all the birds were filled with their flesh.
see also joel 3 zechariah 14 and revelation 14:20