Since "Planet X" is entirely imaginary, probably nothing at all.
the earth would blast
Nothing at all. There is no such thing as a "space tornado". Tornadoes are whirling AIR masses, and there's no air in space. But if you are referering to a wormhole or a black hole then the Earth would probably get sent through the wormhole to the phonomenom's destination.
The theory of an asteroid named Orpheus will hit Earth and destroy civilization in the future years. The asteroid is predicted to hit Mexico. Don't be afraid because it may or may not happen :)
Meteor. Meteorites are the ones that do hit Earth.
they hit an iceberg!
The mesosphere is important because metioroids burn up in this portion of the atmosphere stoping them from going to the earth.
It would be better to ask what would happen if Earth hit a star, as stars are much larger than Earth is. The planet would be vaporized by the intense heat.
Nothing No One Can Hit A Planet
They will hit Earth if, in their orbit around the Sun, they happen to cross Earth's orbit.
the earth would be destroyed
The atmosphere would be fried and the Earth would disentegrate.
Asteroids constantly hit planet earth, it is just that when they enter in contact with the atmosphere they will start burning and getting destroyed, infact what will actually fall to earth is incredibly small dust.
What's gonna happen in 2012 is People say that a planet is gonna hit earth and that planet go's buy every couple thousand years and it was always very close to hitting earth but this time people think that the planet wont miss. This is supposed to happen December 22 or 23 /2012. But i hope nothing is gonna happen.
The name of the (proto)planet that hit (proto)Earth in the Giant Impactor hypothesis is Theia.
There is no special name for them. Any planet can hit by them. Earth gets hit by them.
very little
We don't currently know when a comet will hit planet Earth.
Hitting or getting hit by something as small as an earth sized planet would have no effect on the size of a blue giant. I doubt that the planet would survive as a solid body long enough to actually make contact with such an object.