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(5BYA) The Formation of the Solar System
The solar system was created by the gravitational collapse of a small part of a giant molecular cloud. A few million years later, The Sun was created in an explosion of supernovas. -
(4.6BYA) The Formation of Earth
After the Sun was formed we know from observations and other indirect evidence that there were left over gases and heavier elements. The gravity of the Sun helped to flatten these left overs into a disk and start to fuse them together. This created the planetesimals and planetoids which would later make up the planets. Over time these planetesimals would collide creating even bigger masses. This method is how the Earth was formed -
(4BYA) Rocks and Crystals Form
The oldest known rocks and crystals formed. Also, the first organic molecules were made. -
(4BYA) Living Organisms Affect Atmosphere
Methanosarcina barkeri produces methane during metabolism. Archaea are similar to types of cellular life that populated the Earth 4 billion years ago. -
(3.5BYA) Stromatolites
The oldest evidence for life may be 3.5-billion-year-old sedimentary structures from Australia that resemble stromatolites. Stromatolites are created today by living mats of microorganisms (mostly cyanobacteria, or blue-green algae). These primitive organisms trap thin layers of sediment with their sticky filaments and grow upward to get light for photosynthesis. Modern-day examples of stromatolites can be found in waters off Australia, the Bahamas, and Belize. -
(3BYA) First Photosynthetic Activity
Some forms of life became photosynthetic. Chemical traces of photosynthetic activity have allowed scientists to determine the date. -
(2.2BYA) Rise in Oxygen Levels
The first "pollution crisis" hit the Earth about 2.2 billion years ago. Several pieces of evidence -- the presence of iron oxides in paleosols (fossil soils), the appearance of "red beds" containing metal oxides, and others -- point to a fairly rapid increase in levels of oxygen in the atmosphere at about this time. Oxygen levels in the Archaean had been less that 1% of present levels in the atmosphere, but by about 1.8 billion years ago, oxygen levels were greater than 15% of present levels and -
(2BYA) As Much O2 as Today
Oxygen levels reached today's levels. -
(2-1.5BYA) First Eukaryotes
The first eukaryotes came into existance according to the endosymbiosis theory. A small aerobic prokaryote began to live and reproduce inside a larger anaerobic prokaryote. They then evolved into mitochondria which perform aerobic respiration in eukaryotic cells. Finally the cyanobacteria evolved into chloroplasts which perform photosynthesis. -
(1BYA) Formation of th Ozone
Ozone formed which protected organisms from harmful UV rays so they could exist on land. -
(Today) Radiometric Dating
Radiometric dating is a technique used to date materials such as rocks, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates. -
(1953) Miller and Urey Experiment
Miller's experiment showed that organic compounds such as amino acids, which are essential to cellular life, could be made easily under the conditions that scientists believed to be present on the early earth. This enormous finding inspired a multitude of further experiments. -
(1800-1877) William Henry Fox Talbot
Talbot worked little on his camera between the days of 1835 and January 1839, when the stunning news arrived that a Frenchman, Louis Daguerre, had invented a wholly different means of recording camera pictures with dazzling precision on metal plates. Preempted just at the moment when he was beginning to revisit his earlier experiments with an eye toward publication, Talbot scrambled to stake a claim to priority, to produce pictures that might compare favorably with Daguerre's. -
(1920) Oparin's Hypothesis
Oparin's hypothesis- Oparin and Haldane created a hypothesis that the early atmosphere contained ammonia, H gas, water vapo, and compounds made of hydrogen and carbon. Oparin thought that at high temperatures these gases might form simple organic compunds. Over time they could enter complex chemical reactions and result in macromolecules. -
(1700s) Spallanzani's Experiment
Spallanzani's experiment- He tested the hypothesis that microorganisms grew easily in food. He reasoned that boling broth in a flask would kill of of the microorganisms. He then boiled the broth until the flask was filled with steam. The broth in the sealed flask was clear from organisms. The broth in the open flask was contaminated with organisms. He concluded that the broth only became contaminated when microorganisms from the air entered the flask. -
(1668) Redi's Experiment
Redi's experiment- Redi observed the differnt developmental forms of flys. He questioned the belief that flies were generated from rotting meat. He had some net-covered jars filled with meat and some un-covered jars wtih meat. After a few days maggots were filled with flys and the net-covered jars were not. He concluded that flys only come from laid eggs from other flys. -
(1665) First Microscopes
First microscopes- Hooke first studied nature using an early light microscope that used optical lenses to magnify objects by bending light rays. The discovery of the microscope led to futher discoveries that microorganisms are simple, numerous, and widespread. -
(1862) Pasteur's Experiment
Pasteur demonstrated fermentation is caused by the growth of micro-organisms, and the emergent growth of bacteria in nutrient broths is not due to spontaneous generation, but rather to biogenesis. (Should be 4th down) -
(1980s) Thomas Cech
In a 1982 experiment with the protozoa Tetrahymena thermophilia, biochemist Thomas R. Cech discovered that ribonucleic acid (RNA) could act as its own catalyst, stimulating its own chemical reactions. -
(1966) Endosymbiotic Theory
Lynn margulis wrote a theoretical paper entitled The Origin of Mitosing Eukaryotic Cells. The underlying theme of endosymbiotic theory, as formulated in 1966, was interdependence and cooperative existence of multiple prokaryotic organisms; one organism engulfed another, yet both survived and eventually evolved over millions of years into eukaryotic cells.
