How Far Down is the Center of the Earth?

by Fraser Cain on June 12, 2008

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Everyone has wanted to dig a hole down to the center of the Earth at some time in their lives. I think I was in the 3rd grade, and my friends and I tried to dig down as far as we could go. I never told them my goal, but in my heart, we were going all the way through. In the end we actually got down about 2 meters, but the bottom kept filling in with water.

Of course, digging down to the centre of the Earth was always out of reach.

In order to be able to dig down to the center of the Earth, my friends and I would have needed to dig our way through 6,378 km of rock, mantle, and iron. Most of this journey would be through temperatures hot enough to melt rock, getting as high as 7,000 Kelvin at the center.

The first 35 km or so of digging would be through the outer crust of the Earth. Assuming we could actually get through the solid rock, and keep water from filling back into our super deep hole, we might actually be able to make some progress through this.

Temperatures rise as you get deeper, though. One of the deepest mines in the world is the TauTona gold mine in South Africa, a mere 3.6 kilometers deep. Even though this just scratches the surface of the Earth, temperatures at the bottom of TauTona already get as high as 55°C.

Once you break through the crust, you’re into the Earth’s mantle. At this point, you’re looking at about 3,000 km of rock heated to such a high temperature that it’s a liquid. Volcanoes are points on the Earth when magma from the mantle breaks through to the surface.

How we’d dig through that… I have no idea. But let’s say we could.

Then we’d break through into the core of Earth. This region extends for another 3,500 km or so, and its comprised almost entirely of iron, with a little nickel, and some other trace metals. And it’s even hotter than the mantle above it. This is where temperatures get to 7,000 Kelvin. Assuming we could bore through the iron, and could withstand the heat, we could get down to the center of the Earth.

At this point, we would have traveled 6,378 km to complete our journey. And then another 6,378 km to get through the other side and visit the folks in China.

Sources:
http://en.wikipedia.org/wiki/Earth_radius
http://en.wikipedia.org/wiki/TauTona_Mine
http://en.wikipedia.org/wiki/Mantle_%28geology%29

About 

Fraser Cain is the publisher of Universe Today. He's also the co-host of Astronomy Cast with Dr. Pamela Gay.

Colin Youmans November 21, 2008 at 6:10 AM

If you dropped an anvil down the hole would it fall only 6378 k and just hang there or would it continue on and out the other side?

rosie February 8, 2009 at 10:28 AM

how long would it take me to dig?

rosie February 8, 2009 at 10:28 AM

has anyone gone to the center of the earth?

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