How do we know that earth is really made up of core,mantle and crust know about the volcanos etc,but how sure

thats a good questin i mean hoe do we know theres not cottn candy ander the dirt.mmmmmm that would be so good maybe thats why were floating in space because we are so light from being filled with cotton candy! isnt that so cool. lol. ur right

Actually, you are incredibly correct! The American Government once again has foisted another hoax on the American Public! Man did not land on the Moon, Kennedy was not murdered by Oswald, and the center of the earth is actually made of Ben and Jerry's Very Cherry Garcia Ice Cream. It is a fact, I went there and ate it.

SOMETHING IS CAUSING THE HEAT,

WE define the layers, as we make the rules. By placing exposive devices at various points on the earth, and seismographs at other points, we have determined the earth is separated into layers and have been able to determine their depths based on the spped of sound through certain phases of matter...go to wikepedia

The interior of the earth is studied by both the rocks that ahre exposed at teh surface which are known to have been from the mantle, and by use of siesmic waves. The reason we know the outter core is liquid are two fold. The reaction of siesmic waves from the surface are those of a wave transitioning from a solid to a liquid (as can be replicated using water and a solid) and becasue of the earth's magnetic field (which is produced becasue the inner core is routating in a iron rich metal and is composed of metalic iron producing a huge electomagnetic system.) A siesmic wave generated on the surface (in the crust) travels down to the Moho (the transition zone from the crust to the mantle) and is refrected slightly becasue of the nature of the mantle being "plastic" (not solidly crystiline but not liquid), then the distortion associated with the outer core mantle transition and then the return trip. But it is in fact all based on sound scientific work and not guesses.

GO TO HAWAI ?

Scientist have not made the theories from signs. They have establised facts based upon seismological studies. .

Sound travels faster through dense materials and more slowly through less dense materials. At a boundary layer that divides two layers of sharply different density the sound is partly reflected by the interface. There are earthquakes of varying intensity all over the earth, going constantly at any given time. These earthquakes cause seismic waves, which are just very low frequency sound. By analyzing data from seismometers geologists can use the seismic noise like the sonar of a bat to get a rough picture of what's beneath the earths surface. Large seismic events can be used like the sonar ping of a submarine to get a sharper picture of the earths hidden inner structures. Theories are based on facts, theories do not ever become facts in and of themselves. Theories are broad sketches of complex natural systems which explain the observable facts about said systems.