The age of the universe is said to be about 13.75 billion years old. The method used in determining this age would be attempting to find the age of chemical elements, oldest star clusters, as well as white dwarf stars. Scientists also try to find the universes rate of expansion, and behavior of globular clusters, which are spherical collection of stars. In order to find this, scientists can use radioactive decay to determine how old a given mixture of atoms is in rock samples. In order to find the rate of expansion of the universe, The Hubble constant was the basic cosmological model dependent on density and composition of the universe. Some formulas used by The Hubble Constant is that the earth is composed of primary matter and the age of the universe is 2/3(Ho) with Ho being The Hubble constant (1). Another formula is that the earth is said to have very little matter and the age of the universe is 1/ Ho, which is now considered to be more accurate (1).
The age of the earth is approximately 4.54 billion years old, about 9.21 years after the universe was formed. The main theory of how the earth was formed is the Big Bang Theory, or a star explosion. Some also call is a supernova. This happens in the universe when the wreckage from an explosion crashed into a cloud of gas, bringing in the ingredients for our solar system. The formation of our sun came first from the collapse of a solar nebula. After about ten to twenty million years after this collapse, dust then clustered to grains, to lumps, to boulders, to planetesimas. Soon it became chunks of rock big enough to have their own gravitational field. So, some plantesimals became the embryonic form of planets in our solar system today. As more asteroids and other planets collided with planet earth, crust began to cool and water began to form and collect on the surface.
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Age of the Universe . (2012, December 27). The Age of the Elements . Retrieved January 16, 2013, from http://www.astro.ucla.edu/~wright/age.html
How did the Earth form? | The Planets and our solar System. (2013, January 1). UK2Planets | The Planets in our Solar System. Retrieved January 16, 2013, from http://www.uk2planets.org.uk/how-did-the-earth-form/
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Early earth was not a place for ideal living because it was a fire and hell-like environment. So much so, that scientists even called it Hadean eon, which is an ancient Greek word for down under. It was a place with many volcanoes and some scientists even say there were continental crusts and oceans. Even though it was extremely hot, scientists have found that some bacteria could survive these extreme conditions. According to Watson, by using zircon crystals, they could tell that early earth had a definite wet temperature. The atmosphere consisted of carbon dioxide, water, and volcanic gases. Today, not as many volcanoes exist. No one really knows when life was originated. Asteroids may have hit from time to time, having an effect on life’s atmosphere by causing organic molecules to synthesize. RNA and DNA are the genetic material for all life, and they are made up of long chains of nucleotides. Nucleotides are made up of carbon, hydrogen, nitrogen, oxygen, and phosphorus atoms. An important step in the origin of life is the ability of all living things to reproduce. Starting with RNA being able to self-replicate itself, we then evolve into being able to pass genetic material onto offspring, and then natural selection.
Miller and Urey built an apparatus filled with water, methane, ammonia, hydrogen, but no oxygen. They hypothesized that this was the mixture of the atmosphere of early earth and boiled and condensed the water to keep it circulating. Miller and Urey kept this going for a week and used paper chromatography to be able to show that many amino acids and some other organic molecules were now in the flask. Many other scientists have tested this experiment and found that amino acids, protein molecules, adenine, and other nucleic acid bases were present.
Some theories suggest an electric spark could have helped generate these amino acids and sugars in the atmosphere, others suggest the first origins of life could have met on clay. Alexander Graham Cairns- Smith says clay could help the organic compounds become concentrated and organize into patterns similar to genes today. Some scientists theorized that life was brought from somewhere else in space rather than beginning on earth, which is also known as panspermia. In reality, no one is sure of how life began because no one was around to know, but these theories have helped us gain a sense of fascination and knowledge of how life was originated.
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Early Earth Not So Hellish, New Study Suggests | LiveScience . (n.d.). Science News – Science Articles and Current Events | LiveScience . Retrieved January 14, 2013, from http://www.livescience.com/241-early-earth-hellish-study-suggests.html
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Radiometric dating is used to date materials based on comparison between the observed abundance of a naturally occurring radioactive isotope and its decay rate (1). Some different types are radiocarbon dating, potassium-argon dating, and uranium-lead dating. They provide important information about fossil ages and the rate of evolutionary changes. Radiocarbon dating is used to estimate the remains of materials with carbon as of 58000 to 62000 years ago (2). Potassium-argon dating is used to measure the product of radioactive decay of an isotope of potassium into argon. This method works for calculating the age of samples a little over a few thousand years. Uranium-lead dating on the other hand, can estimate the age range of a sample from about 1 million to 4.5 billion years ago (3). This method has two separate decay chains, uranium series, and actinium series, occurring by a series of alpha decays. It is important to have different types of radiometric dating because the earth has been around for quite some time and a lot of changes has happened in each era, epoch, and eons.
There was not as much oxygen dependency in earth’s early atmosphere as there is today. The result of oxygen presence is mainly because of volcanic activity as well as oxygen producing organisms like cyanobacteria, in the oceans of early earth. Cyanobacteria as well as blue-green algae produced their energy anaerobically, releasing oxygen and taking in CO2, and releasing oxygen. Oxygen gained a permanent presence in earth’s atmosphere 2.45 billion years ago for the aerobic organisms that inhabited.
When the plates of earth’s crust shift, along with their liquid layers below, this is called plate tectonics. This results in how our continent and land mass appears throughout time. Kenorland, one of the first supercontinents of early earth broke up about 2.6 billion years ago. Another supercontinent called Columbia then formed about 1.8 years ago, and after that Rodinia formed from Columbia’s remains, that broke 550 million years ago. The breaking of these supercontinents caused the earth to have freezing temperatures. Oceans broke out and then Pangea formed and split into two supercontinents called Laurasia and Gondwana. Laurasia consists of what is now North America, Asia, Europe, and Gondwana of South America, Africa, India, Antarctica, and Australia. These continents in time spread and broke to form what we have today.
Mass extinctions are when a species has become wiped out. There have been about five mass extinctions that have occurred so far. The first that occurred was during the Paleozoic era which was the end of the Ordovician. Scientist found that 60% of terrestrial and marine lives had disappeared out of nowhere. The next mass extinction was the late Devonian. The environment no longer provided enough for the survival of these organisms. The third mass extinction was the end of the Permian during the Mesozoic era, where scientist found that 85.5% of all marine species became extinct. The Triassic extinction is the fourth one that happened in the Mesozoic era. Marine invertebrate’s population decreased by 50%. The last mass extinction caused the dinosaurs, as well as plants and other tropical marine life to die out during the Cenozoic era. Global temperature and oceans caused flooding for 40% of all continents.
One theory is that because of the quick change of CO2 in the atmosphere, mass extinction occurred. While CO2 in the atmosphere changed, surface layers in the deep oceans began to sink. CO2 increased too rapidly for creatures to adapt in time. Some theories suggest an asteroid caused some mass extinction, hitting the earth. The asteroid might have blocked the sun’s rays or cause the earth’s temperature to rise too high. Periods of intense speciation happens because of mutations. Mutations come from ionizing radiation and other factors. Species that do survive, mutate and cause this speciation. Some researchers say that Earth is hitting the sixth mass extinction because many species are endangered and decreasing population. Researchers also found that major mammals have become more and more rare that they could be extinct in about 30 years. These endangered species, researchers found, may be the result of human activities like habitat destruction and hunting. So, we are basically in a sixth mass extinction, because human play the main cause.
Biello, D. (2009, August). The Origin of Oxygen in Earth’s Atmosphere. Scientific American. Retrieved from: http://www.scientificamerican.com/article.cfm?id=origin-of-oxygen-in-atmosphere
Plastino, W.; Kaihola, L.; Bartolomei, P.; Bella, F. (2001). “Cosmic Background Reduction In The Radiocarbon Measurement By Scintillation Spectrometry At The Underground Laboratory Of Gran Sasso”. Radiocarbon 43 (2A): 157–161.
Parrish, Randall R.; Noble, Stephen R., 2003. Zircon U-Th-Pb Geochronology by Isotope Dilution – Thermal Ionization Mass Spectrometry (ID-TIMS). In Zircon (eds. J. Hanchar and P. Hoskin). Reviews in Mineralogy and Geochemistry, Mineralogical Society of America. 183-213.
Wilkins, A. (2011, January). A History of Supercontinents on Planet Earth. io9. Retrieved from: http://io9.com/5744636/a-geological-history-of-supercontinents-on-planet-earth