how people know in the center of earth is liquid?? secondly how do they now its diameter?

Answer 1

When an earthquake occurs, three kinds of waves are released. One of those kinds, a shear wave, cannot travel in liquid. Thus when we look at the waves coming from an earthquake that happened on the other side of the Earth, there is a shadow where the shear waves aren't detected. By measuring the size of this shadow, and knowing the diameter of the Earth, we can figure out how much is liquid, and where the liquid is located (not the very center). See the link below.

Answer 2

Yes, the center is probably solid and we say this both because of seismic data (about which I know nothing) and because the elements that proposedly compose the center would be solid at the predicted temperature and pressure.

You can calculate the diameter yourself fairly simply by doing an experiment if you have a friend at a different latitude and similar longitude. Just call your friend and ask him to stand outside and measure the length of his shadow, and his height. You do the same. The sun is far enough away that the actual distance doesn't matter, and you can do a little trig to calculate the diameter of the earth. You can look up details here: http://www.astro.princeton.edu/~clark/MeasECAct2.html

Answer 3

The inner core is not liquid - it is solid. This is due to the extremely high pressure upon it. It is reasonable to suggest that the remainder of the material contained between the crust and the core is molten due to the extremely high temperatures that exist there. Our real evidence that it is molten - Lava (Magma when under the crust).

How do we ESTIMATE how big it is? That's a lot more complicated and I'm not sure I can give the best answer - but it absolutely to do with the volume of the earth, the density of the earth, the composition of the materials (elements) contained within the earth and their states relative to heat and pressure. From that and a lot of number cunching the diameter of the core could be estimated.

Answer 4

Seismic waves are of two main types:
Primary (P) waves which are longitudinal. Longitudinal seismic waves can travel through both liquids and solids;
Secondary (S) waves which are transverse and travel through solids only.
(There are other waves but they aren't needed for this answer).
Earthquakes/ large explosions can be detected at seismometers all around the world, but there is a 'shadow' where only P waves (not S waves) can be detected. This shadow occurs on the opposite side of the earth to the earthquake and can be explained by there being a liquid region in the centre of the earth.
The velocity of seismic waves is known which could be used to ascertain the diameter of the earth.

Answer 5

certainly, i've got self assurance good count occupies extra area than liquid count. yet whilst the earth's middle have been to solidify someway, resisting the crushing tension of gravity attempting in ineffective to start up a fusion reaction...i assume the Earth's diameter might certainly improve, and gravity may be much less, because of the upward thrust in radius without a upward thrust in mass. yet that'll in no way ensue because of the fact the melting factor of the minerals at earth's middle is far too low to stand up to the warmth produced via the gravitational forces interior of it.

Answer 6

The inner core is iron. By measuring the magnetic flux around the earth one can quantify that iron. In addition the other data mentioned earliar also taken in to account to determine the size etc.

Answer 7

Technology

Answer 8

They know because of the lava that has come forth from volcanoes(it had to come from SOMEWHERE,) and for the second part, because they have done tests. I'm no scientist so I couldn't tell you what type of tests.

Answer 9

The same way it is known to some that God exists. Study , experience and logic.