If you need to keep track of time, OnlineClock.net is an excellent tool in which to do just that. Our time tools site can track the beginning and end of nearly anything imaginable.
But have you ever wondered what the beginning of existence would have looked like if it were tracked as though it happened during a measurement of 24 hours? What if we had an Earth clock? When and where would time begin and end during the creation of life?
If we looked at Earth’s creation through a clock measuring a 24 hour time span, dinosaurs, mammals and humans would be last in the line of creation on the clock. The National Science Foundation terms the creation of Earth and its life forms as emergence.
Earth and life as we know it began nearly four billion years ago.
Aging Earth is a very complex mystery that scientists have faced for many years. The process of the creation of planet Earth adhered to all the laws of chemistry and physics, yet the details are quite confounding and scientists are still chasing them with fervor. How did this clock of life begin to tick?
Theories of the Genesis of Life
Astrobiologist Robert Hazen, Carnegie Institution and George Mason University, has some very interesting theories on the origin of Earth. Through experiments that subjected elements which were found near deep-ocean vents, Hazen hypothesizes that life probably began in such an environment as the ocean. He believes that the beginnings of life were nourished by the rich mixture of the oceanic water and was energized by Earth’s tectonic forces. That is such a good explanation for where life began, but is it possible that life began or exists on other planets as well? Without being privy to direct observations of other worlds, scientists are constantly looking for ways of discovering whether life exists beyond Earth. Hazen theorizes that the origins of life on Earth, and possibly on other planets, can be modeled as a sequence of events that are considered to be the transformation of the lifeless geochemistry of oceans, minerals and atmosphere into a living planet.
Hazen states that it all comes down to emergence. Emergence, in a common sense, refers to a shadowy figure from a dark place. Hazen thinks that emergence is like a submarine from the bottom of the sea, or a plot in a novel. Hazen pens the term emergence poetically and nicely packages it in his book; however, emergence has developed quite a different meaning in the field of science. Researchers refer to emergence to describe a process of complex systems that arise from simpler systems.
The process usually begins with a synthesis of bio-molecules which are in a variety of pre-biotic environments. One of the key steps on Earth in its transition from geochemistry to biochemistry was the appearance of the first self-replicating molecules, and the jump-start of rapid evolution through competition and the process of natural selection.
This sequence of steps is very important in studies of the origins of life. According to Hazen, the sequence of these steps reduce a very complex process into a series of manageable chemical episodes. Each step is a process for laboratory experimentation or theoretical modeling of the beginning of life on planet Earth, and perhaps planets in the distance of space.
The Events of the Earth Clock
According to astrophysicist Neil deGrasse Tyson, on a 24 hour clock, Earth’s birth completion began at midnight, but its violent history began a long time before that. Before the birth of Earth, huge ancient stars reached the end of their life and exploded. This explosion created many supernovas that produced all the chemical elements that we know today. Over a span of time, gravity took hold, and the cloud of stardust created by the explosion collapsed. This stardust then spun into an enormous rotating disc. This rotating disc is known as the solar nebular. The particles in the solar nebular collected like dust bunnies underneath a bed. These particles collided, and some of the particles adhered and formed masses, one of which was Earth.
Below are the events of the 24 hour Earth clock. We have provided explanations for those events that are not self-explanatory:
- 00:00 – 3:00 a.m. – Meteorite Bombardment
Scientists have found evidence that Earth was bombarded by meteorites approximately four billion years ago. This has implications that these giant impacts annihilated any possible existing life forms at the time, but it also gave Earth complex molecules from carbonaceous chondrites, which are specific types of meteorites.
- 4 a.m. – Origin of life
- 5:36 a.m. – Oldest fossils
- 6 a.m. – 1:52 p.m. – Abundant banded iron formations
Banded iron formations are distinctive sedimentary rocks. These rocks contain banded iron layers. Banded layers that are rich in iron are featured in sediments during much of the early history of Earth.
- 2:08 p.m. – Single-celled algae
- 6:08 p.m. – Sexual reproduction
- 8:28 p.m. – Seaweed formation
- 8:48 p.m. – Jellyfish
- 9:04 p.m. – Trilobites
Trilobites are a well-known fossil group from extinct marine anthropods.
- 9:52 p.m. – Land plants
- 10:24 p.m. – Coal swamps
- 10:56 p.m. – Dinosaurs
- 11:39 p.m. – Mammals
- 11:58:43 p.m. – Humans
Reducing Earth’s creation to a clock may seem like a strange thing to do, since so much of what happened took a lot more time than 24 hours. According to research scientists, it gives us a picture of what kind of pause may have taken place between the events that formed the picture of life as we know it today. While it’s nice to have a number or an age of Earth, it may spark a curiosity of how scientists are able to tell us the age of Earth.
The exact age of Earth still cannot be calculated. The four billion year age is an educated approximation based on scientific evidence. Rock formations are one of the ways the Earth’s age is measured. Over time, plate tectonics destroys rock and impedes an exact planetary aging measurement. Ancient rocks, which are more than 3.5 billion years old, have been found all over the planet. The consistency of the ages of the rocks on every continent gives science the confidence that they are correct in aging Earth within a few thousand years.
One of the interesting features of the ancient rocks that is that they are not from a primordial crust, but are lava flows and sediments that were deposited in shallow water. This is an indication that Earth’s history began well before the rocks were deposited. For instance, In Western Australia, individual zircon crystals found in younger sedimentary rocks have ages of 4.3 billion years, making these small crystals the oldest materials to be found on Earth to date. The source rocks for the zircon crystals still have not been found. The ages of the crystals and the oldest rocks show that the Earth is at least 4.3 billion years old, but they don’t reveal the exact age that Earth was formed. Since no one was present to witness Earth’s beginnings, we have to rely on scientific evidence to point us to the age of Earth. There are other ways in which scientists can tell when Earth began.
Meteorites are an excellent way of dating Earth. There are more than 70 meteorites of different types whose ages have been measured using radiometric dating techniques. The results of those tests reveal that the meteorites were present 4.53 and 4.58 billion years ago.
Fossil Evidence: Early life forms
The earliest evidence of fossil cells were found in sedimentary rocks in Australia. These fossils depict unicells in spherical, fibrous growth formations which are clumped together. These fossils were present 2.8 billion years ago. There are several avenues of evidence that prove life has been present for most of Earth’s history. Hypotheses about the origins of life vary in terms of the environmental context, and as to whether replication came about first in the earliest of life’s cells. Prokaryotic ecosystems ruled the first two billion years of life on Earth. Eukaryotes are thought to have arisen from prokaryotic ancestors by way of stages of endosymbosis. Our bodies have ten times as many cells as prokaryotic symbionts within our human genome.
Life is nearly as old as Earth itself. The Earth clock shows life and humans emerging close to midnight. It is amazing that we evolved and survived, considering the climate of the rest of the universe.
Interestingly, we should note that the supernova created an explosion which resulted in a collection of molecules and chemicals from the universe here on Earth. As one of the life forms of Earth, we are made from the same compositions of Earth as well as the universe. We are in the universe, and the universe is in us. (Hey, that’s a really cool thought…)
The science of dating the universe and the planets is still evolving. There are many answers that are yet to be discovered. It is truly amazing what has been found just in the last century. Looking at the emergence of Earth and its life forms on the 24 hour clock allows us to see just how fast life actually evolved on Earth, since Earth had such a hostile environmental beginning. If you really think about it, we made it here in record time!
Here at OnlineClock.net, we are excited about Earth science and we anxiously await to hear more about new discoveries that will enhance the Earth clock. We will faithfully cheer on our many outstanding scientists, and we wish them well in their continued study of planet Earth!