Snowball Earth: When Ice Reached the Equator
Snowball Earth was a time when our planet may have frozen nearly from pole to pole, testing life and setting the stage for later biological change.
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Big-Bang-Timeline
The Big Bang Timeline
Moon Formation
In a cataclysmic event, a Mars-sized object named Theia collided with the early Earth, sending massive amounts of debris into orbit. This debris coalesced over time to form the Moon, which eventually became tidally locked to the Earth, stabilizing the planet’s axis and paving the way for the development of life. The Moon is comprised
Late Heavy Bombardment
Visual Craters of the Moon! In a period known as the Late Heavy Bombardment, the solar system experienced a intense barrage of asteroid and comet impacts, with many large objects striking the Earth and Moon. This event likely occurred as the giant planets Jupiter and Saturn migrated to their current orbits, sending smaller bodies into
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Great Oxidation Event: Third Atmosphere
About 2.4 billion years ago, Cyanobacteria “hacked” the sun to split water, releasing oxygen as a byproduct and triggering the first global environmental catastrophe and subsequent biological reset.
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Second Atmosphere: Carbon Dioxide & Nitrogen
Deep orange or reddish-brown atmosphere: The second atmosphere’s formation was crucial and occurred just before or alongside the formation of Earth’s oceans, which directly supported the evolution of organic molecules and prebiotic microenvironments. The second atmosphere began to develop around 4.5 to 4 billion years ago, as volcanic outgassing released gases trapped in the Earth’s
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First Atmosphere: Hydrogen & Helium
Likely white or grayish atmosphere: The first atmosphere developed first but was not directly involved in the development of life. The first atmosphere formed shortly after Earth’s formation around 4.5 billion years ago. This initial atmosphere was primarily composed of hydrogen and helium, the lightest and most abundant elements in the universe, which were captured from
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First Oceans: Fresh Water
As the Earth cooled following its formation, outgassing from volcanic activity released water vapor and other gases into the atmosphere. When the Earth’s surface cooled sufficiently, this water vapor condensed and fell as rain, filling the basins that would become oceans.
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Second Oceans: From Fresh to Salty
The process of salination likely began soon after the oceans formed but took hundreds of millions of years to reach the salinity levels similar to what we see today. The oceans were likely significantly salty by about 3.5 billion years ago. Salinity increased primarily through the weathering of rocks and the leaching of minerals (including
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Interstellar Clouds: Organic Molecules
The synthesis of simple organic molecules such as formaldehyde (H₂CO), methanol (CH₃OH), and simple hydrocarbons in the dense molecular clouds of the interstellar medium occured once sufficient carbon was present. This process has been ongoing for billions of years but became more prevalent as the universe aged and more carbon became available. Big History Thresholds:
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Inorganic Precursors to Organic Molecules
The chemical evolution from inorganic precursors to organic molecules is a fascinating story of transformation driven by Earth’s dynamic early conditions and possibly assisted by the input from space in the form of meteorites rich in organic compounds. During this period, the Earth witnessed a series of complex chemical reactions facilitated by its primordial atmosphere,
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Big Bang Expansion
13.8 billion years ago, space itself began expanding and cooling, setting the stage for particles, atoms, stars, galaxies, planets, life, and us.
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Formation of Prebiotic Microenvironments
Alongside or following the chemical evolution of organic molecules, the formation of prebiotic microenvironments, such as hydrothermal vents or warm little ponds, provided niches where concentrations of organic molecules could interact. These environments could have been crucial for the assembly of complex organic molecules and the initiation of catalytic cycles.
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Chemical Evolution of Organic Molecules
While the 4.4 billion years ago is a guess as to when these processes might have started, the 4.1 billion years ago guess is a better representatoin of current understanding on when the needed building blocks of life evolved. Before the appearance of self-replicating molecules, there was a crucial phase of chemical evolution where simple
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Cellular Membranes
The formation of cellular membranes represents a pivotal development in the pre-life world, enabling the creation of defined boundaries for primitive cells. These membranes, likely formed from simple lipid bilayers, provided a controlled environment for chemical reactions and played a critical role in the emergence of the first cell-like structures, distinguishing them from their surrounding
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Brand New Constellations
The constellations we recognize today will be vastly different in a million years due to what astromers call “proper motion” of stars. This will transform our night sky, creating new constellations from stars that have shifted positions, presenting future astronomers with a completely new celestial map to study. Because of stellar motion, our current Star
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Lambda Model: Heat Death of the Universe
The Lambda Cold Dark Matter model of the universe predicts a Big Freeze. The Big Freeze is projected sometime after 10100 years from now. That’s a set of googol years from now. After billions is trillions then quadrillion. After quadrillions is Quintillion, Sextillion, Septillion, Octillion, Nonillion, Decillion, and finally a GOOGOL. This number is beyond
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Black Dwarf Sun
Over an incredibly long timescale, the Sun’s white dwarf remnant could cool enough to become a black dwarf, a theoretical stellar remnant that emits no light. Although speculative, theoretical models give us insight into the lifespan of the Sun as a white dwarf. After transitioning into a white dwarf, the Sun is expected to cool
Formation of a New Solar System
After shedding its outer layers and engulfing the inner planets during its red giant phase, the Sun will leave behind a white dwarf. The remaining material could potentially form a new planetary system around this white dwarf.
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Milky Way-Andromeda Collision
The Milky Way and Andromeda galaxies are expected to collide and merge into a single elliptical galaxy. Despite the dramatic nature of this event, the vast distances between stars mean that direct stellar collisions are unlikely.
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Birth of the Milky Way
Current scholarship generally places the formation of the Milky Way between 200 and 600 million years after the Big Bang, during the period of early galaxy formation that followed the forging of Population II stars. Some of the oldest stars within the Milky Way belong to this Population II category, with estimates for their formation
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