Since magma = molten rock = liquified rock as a result of tremendous temperatures apparently has existed since earth was formed = billions of years, how is the heat maintained? Is oxygen necessary produced by chemicals in those areas? In lieu of volcanic eruptions, where is the constant energy transferred? And why is earth’s core solid?
I didnt check the links from astro, but this question taxed the brightest minds at the turn of the century. Essentially, the earth should have cooled down within millions of years if it was just a molten rock. This caused endless confusion with the geologists of the day as they knew the earth was much much older. What was found later to keep the interior hot is the heat released by radioactivity in the rocks, probably first elucidated by Rutherford round 1900.
**turn of last century ** - keep forgetting (I am too old for this milleneum)
Basically, the two main reasons for the why the Earth is still so hot within are:
- Rock is a very good insulator.
- Heat is still being produced by the decay of radioactive elements. Uranium-238, for example, has a half-life of 4.5 billion years. In other words, half of the U-238 that was present when the earth was formed (which was, coincidentally, 4.5 billion years ago) is still present.
I read recently that it is estimated that the Earth’s inner core has cooled by no more than 200 degrees F since the Earth was formed.
It is my understanding that the inner core is solid simply due to the intense pressure.
As far as your question about the necessity of oxygen, no oxygen is necessary to produce the heat within the Earth because the heat-producing reaction is radioactive and has nothing to do with combustion.
Besides decay heat from radioactive elements, the Earth has a small surface area relative to its volume. Area is proportional to the square of size, where volume is proportional to the cube of size.
My astronomy professor gave this as the reason that Mars is now a barren planet. Its smaller size led it to cool more quickly than the Earth. When the core solidified, it lost its magnetic field. Without the magnetic field to protect it from the solar wind, and a lower escape velocity due to less mass, most of its atmosphere was stripped away.
If radioactivity keeps the temperatures high and this process has been going on since earth was produced, does the radioactivity that escapes during a volcanic eruption ever reach the point where people die or severely maimed from atmospheric circulation of the radioactive particles?
And does the radioactivity escape thru cracks in the earth crust that allows a continous flow of radioactive materials?
Wait, doesn’t the moon exert tidal force on the planet, contributing to friction?
I think you’re misunderstanding how radioactivity works. Radioactive materials become less radioactive over time and make the stuff around them hotter as a result. Just because the radioactivity of materials in the Earth have been helping keep the Earth’s interior warm for billions of years doesn’t mean everything coming out the Earth has been made highly radioactive. It is actually much less radioactive than it used to be.