The Production of Heavy Elements

The Collision of Geology and Physics in Stars and Supernovae

Mar 22, 2008

The fact that Earth is a rocky planet is a large reason it is capable of supporting life. The heavy elements necessary for this were created in stars and supernovae.

There are few less incendiary statements than this: The Earth is, for the most part, made up of inorganic rocks and metals. Yes, of course there is also some water and some organic material such as plants and animals, but for the most part it is just good, old fashioned rocks and metals.

The Truth about Rocks

Rocks and metals, in reality, are truly the lifeblood of the planet Earth. They are not only necessary for survival, but they are highly beneficial from a scientific perspective, and they have the tendency (though one must really look closely to find it sometimes) to be rather unique and interesting as well.

First, one may be advised to consider just how privileged Earth is as a planet to possess a rocky surface in the first place. It may seem like a rather mundane thing, but if one looks into our solar system and then to the universe at large, it might be realized that it did not necessarily have to be this way. Earth could very easily have ended up a gaseous planet like Jupiter and Saturn (and every planet so far discovered outside of this solar system.

So what is to be thanked for the prevalence of rocks and solids which make up this rather privileged little planet?

The Production of the Elements

Often times when one looks into space, into all the glorious far-off stars and galaxies, these things are viewed as being distant and rather aloof – not much interfering with the lives of Earthlings. One may even be found themselves wondering if these distant things are entirely necessary.

If all those other celestial bodies had never arrived on the scene, would Earth be any different?

The answer to this is unequivocally, yes. If those other stars and galaxies never existed, neither would Earth as it is currently known.

The vast majority of the universe is comprised of just two elements – hydrogen and helium. These are the lightest two elements, and the ones to which all other elements eventually decay by way of alpha and beta radiation (before they themselves eventually decay into even more fundamental particles.

Technically speaking, there should be absolutely no elements in the entire universe “heavier” than these two. Clearly this is not the case. So how did these heavier elements get produced?

When the clouds of hydrogen and helium in the universe began to be pulled together by the force of gravity, they eventually formed into stars – bodies dense enough that in their core they began to undergo nuclear fusion, where the light elements are “smashed” together with such force that they actually fuse together to form new elements, releasing tremendous energy in the process, which continues to fuel nuclear core.

In this manner, many of the heavier elements in the universe are created and then spat out into the void, where they might eventually coalesce into slightly denser bodies, such as gaseous planets such as those beyond our own asteroid belt.

The Heavy Elements

Still, however, this process only accounts for a certain number of heavier elements – generally speaking, those elements lighter than iron (atomic number 26). Earth, however, is made up of elements even as heavy as Uranium (atomic number 92), the heaviest naturally occurring element, which is far too complex to be created in a simple star.

These heaviest elements are only created under very specific circumstances – in the tremendous heat and pressure that is created when a star burns through all of its nuclear fuel (which occurs faster for large stars and slower for small stars), causing instability and a massive explosion known as a supernova.

It is in the process of these rather rare explosions that the heavier elements are created and thrown into space, eventually coalescing into clouds and being pulled into planetary formations.

And it is through a combination of all of these processes that the many elements, all of which necessary for our survival, were formed into what we now know as rocks. Geologists (those who study such things as these) can use this knowledge of the history of the chemical elements, to decipher many things based on how rocks are distributed through the crust of the Earth, what types of rocks they are, and what chemicals they are composed of.

The Importance of Geology

By studying rock formations here on Earth, scientists have also been able to deduce the composition of the interior of the Earth to a fairly reasonable extent, as well as its long and exciting history.

Fault lines and mountain ranges convey the size and shape of the various plates forming the crust of the Earth, and detailed seismic and radar measurements tell us what kind of rocks lie deeper below the surface, forming the mantle and core of Earth.

Rocks, in other words, create for geologists a great jigsaw puzzle, which with enough scholarship and wisdom might be able to put together one day in order to form an understanding of the Earth and the rest of the universe far surpassing that which exists today.

The copyright of the article The Production of Heavy Elements in Geology/Ecology is owned by Isaac M. McPhee. Permission to republish The Production of Heavy Elements in print or online must be granted by the author in writing.