The oldest rocks on Earth are zircon crystals. These highly refractive gemstones are often used to imitate diamonds or cubic zirconias in jewelry. Geologists have now announced the results of a study that has determined that zircons are quite possibly remnants of an ancient asteroid collision with Earth.
Other than simply having the pleasure of knowing you may have a bit of outer space asteroid glittering on your finger or about your ears, neck or wrist, what good is this information? Well, for one thing it dispels the previous theory that zircons were created by tectonic plate upheavals. But, more importantly, it helps scientists understand climate change. Yes, you heard the gringa right, climate change. A rock’s origins can often indicate what was going on with water on the planet at the time the rock was formed. Since zircon’s are produced by asteroids, Earthlings can also learn about the part of the cosmos that it originated from.
Researchers from Trinity College Dublin (Ireland) collected crystals from an impact crater that is considered “young”. Scientists wanted to compare the “young” crystals with older crystals from the Sudbury crater in Ontario, Canada. Sudbury is the best preserved impact crater on Earth and is about two billion years old.
The samples were taken to Stockholm’s “Swedish Museum of Natural History”. Comparisons concluded that the older crystals were the same as the younger ones. This then disproved the argument that the ancient zircon crystals could not have formed at the time the impact occurred. So, now we know that they could and probably did, making zircons the oldest rocks on Earth, as old as four billion years old which is the age of the oldest impact crater on our planet. The researchers also believe this supports the narrative that early Earth saw many more asteroid impacts than in its later life.
So, what this new determination tells mankind is that about four billion years ago an asteroid slammed into Earth. The crystals were able to form because water was present. Best estimates place the Earth’s age at four and a half billion years old so logic would assume then that it has always been a watery planet. And what’s the big deal about an old, watery Earth?
Well, for one thing, water was required for life as we know it today to have evolved. But, the new discoveries about the crystals still does not solve the mystery of how life originated on planet Earth in the first place. And there are many theories on this subject that argue their own merits. Here are a few:
Electrified Primordial Soup – This school of thought believes that in the beginning of Earth’s life as a planet there was a life-giving electrical shock to the planet, such as lightning, that interacted with the ammonia, hydrogen and water on the planet. Lightning would deliver more than just a jolting electrical shock. The atmosphere, being filled with ammonia, hydrogen and water, would react with the electricity and create amino acids and sugars. These are the building blocks of microbial life.
Clay – A Scottish chemist has offered the theory that mineral crystals in clay is where all life began. He believes it is possible that clay, possibly at the bottom of the sea, was the perfect surface for molecules to organize themselves into patterns of amino acids and proteins which would later become DNA. Once the DNA evolved independently it no longer needed the clay medium but could organize itself on its own.
Hydrothermal Vents – Even now ocean biologists discover ecosystems surrounding hydrothermal vents deep within the Earth’s oceans that are teeming with life. Concentrations of molecules and minerals exist with the rocks surrounding these vents interacting with the hydrogen rich molecules provided by the vents action.
Panspermia – The hitchhiking life surviving the impact of an asteroid with Earth is yet one more possibility. If this theory is true, then the puzzle of the origins of life is not really to be worked out here on Earth, but to be solved by traveling the cosmos to find where it came from out there.
Although the many theories of how life originate on Earth are quite varied in their ideas, they all have one common thread… water. That would mean if the original microbes that evolved into humans over billions of years originally came from somewhere in outer space, to discover or “home planet”, Earthlings have to study planets that either have water now or had it at some time in their own history. By understanding this, a person then can understand the inspiration behind every space mission and why the space agencies of the world want to travel ever farther. They are not looking for little green men. They are looking for little molecules of water or ice. And one day, we may all call home a rock that exists in another galaxy or solar system.
Image credits: www.en.wikipedia.org