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 […]
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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GOE: The Great Oxidation Event started enriching the atmosphere with oxygen beginning around 2.4 billion years ago. It marked one of Earth’s most dramatic transformations. Initiated by the widespread activity of photosynthetic cyanobacteria, this period, known as the Great Oxidation Event, gradually saw the accumulation of oxygen that was initially absorbed by oceanic iron. As
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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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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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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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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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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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Following the appearance of self-replicating molecules, the RNA world hypothesis suggests a period where RNA served both as genetic material and as a catalyst for chemical reactions. This phase emphasizes the central role of RNA in early life forms, prior to the evolution of DNA and proteins. The RNA world could be considered both a
Between the development of metabolic pathways and the formation of cellular membranes, there might have been a phase involving the assembly of protocells. These protocells, formed from self-assembled lipid molecules creating vesicles, could encapsulate nucleic acids and metabolic molecules, offering a primitive model for cell-like structures. Protocells represent a bridge between non-living chemical systems and
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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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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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The appearance of self-replicating molecules, such as RNA or similar nucleic acid analogues, signified a monumental leap towards life. These molecules had the ability to store genetic information and catalyze their own replication, laying the foundational mechanism for heredity and evolution by natural selection, driving the complexity forward towards the emergence of life as we
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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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The Earth and the other planets formed 4.5 billion years ago from the same cosmic cloud—the primordial material which gave birth to the Sun. The dust and comets—the rocks—were composed largely of hydrogen, ice, carbon, and nitrogen.
4.6 billion years ago, a cloud of gas and dust collapsed under the force of its own gravity to form our solar system.With the Sun at its center, glowing, the planets had not yet formed. The Sun, a G-type Population 1 star, shines brightly with a surface temperature of about 9,400 degrees, 5,500 Kelvin, and
This supernova was observed by Chinese astronomers in 185 CE. The Chinese kept meticulous astronomical records for centuries, including observations of what modern scientists interpret as supernovae. Chinese astronomical records from 185 AD describe the appearance of a “guest star” in the constellation now known as Circinus. This guest star matches the expected location and
First DNA Life: From chemical reactions before 4 billion years ago to replicating molecules about 4 billion years ago to DNA based life then to LUCA, the only DNA based branch to survive. Meaning, DNA based life likely started before LUCA, and LUCA is the only branch to survive the test of time. From LUCA
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Around 1.7 billion years ago, a branch of protozoa, an advanced branch of the eukaryote cells, split into animals, plants, and fungi. These three separate lineages are the ancestors of modern plants, fungi and animals. 1.7 billion years ago: Plants diverge from the common protozoa ancestor. 1.5 billion years ago: Fungi and animal branch emerges.
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The earliest known life on Earth are fossilized microorganisms found in hydrothermal vent precipitates. Currently dated to about 3.42 billion BCE. These microorganisms were prokaryote cells. Single celled organisms with no nucleus and had early simple DNA. More complex DNA in a nucleus evolved about 1.5 billion years later in Eukaryotic cells, circa 2 billion
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