Update: 2018-04-23 06:42 PM -0400


History of the Earth


A collection from Wikipedia: - https://en.wikipedia.org/wiki/History_of_Earth 180309
and other websites.

Downloaded and edited by U Kyaw Tun (UKT) (M.S., I.P.S.T., USA), and staff of Tun Institute of Learning (TIL) . Not for sale. No copyright. Free for everyone. Prepared for students and staff of TIL Research Station, Yangon, MYANMAR 
 - http://www.tuninst.net , www.romabama.blogspot.com

index.htm | | Top

Contents of this page

  Titan Impact Hypothesis : to differentiate from Giant Impact Hypothesis
1.0.0. Eons


The following are still linked to original website
2 Geologic time scale
3 Solar System formation
4 Hadean and Archean Eons |
4.1 Formation of the Moon
4.2 First continents
4.3 Oceans and atmosphere
4.4 Origin of life
4.4.1 Replication first: RNA world
4.4.2 Metabolism first: iron–sulfur world
4.4.3 Membranes first: Lipid world
4.4.4 The clay theory
4.4.5 Last universal ancestor
5 Proterozoic Eon
5.1 Oxygen revolution
5.2 Snowball Earth
5.3 Emergence of eukaryotes
5.4 Supercontinents in the Proterozoic
5.5 Late Proterozoic climate and life
6 Phanerozoic Eon
6.1 Tectonics, paleogeography and climate
6.2 Cambrian explosion
6.3 Colonization of land
6.4 Evolution of tetrapods
6.5 Extinctions
6.6 Diversification of mammals
6.7 Human evolution
6.7.1 Civilization
6.7.2 Recent events
7 See also
8 Notes
9 References
10 Further reading
11 External links

UKT notes
The Giant-Impact Hypothesis for Moon's Formation Is in Doubt


Contents of this page


From Wikipedia: - https://en.wikipedia.org/wiki/History_of_Earth 180309

The history of Earth concerns the development of planet Earth from its formation to the present day. [1] [2] [UKT ¶]

UKT: 180310: We usually assume that everything, and every event must have a beginning. So, what is the beginning of formation of Earth? Our Earth has a moon, which I will capitalize as the Moon. When was its formed? There are at least 4 theories on how the Moon was formed. See: - https://www.mnn.com/earth-matters/space/stories/4-theories-about-how-moon-formed 180310

But, first we see what Prof. Stephen Hawkins has to say on Formation of the Solar System. See downloaded video is in the Geology section of TIL HD-VIDEO and SD-VIDEO libraries:
- StephenHawkings<Ô> / Bkp<Ô> (link chk 180311)
"Our Solar system, the place we call home, lies about 26 thousand light-years from the centre of our Galaxy, the Milky Way. We are about two thirds of the way out ..."

Fission theory - In the 1800s, George Darwin, the son of Charles Darwin, suggested that the moon looked so similar to the Earth because at one point in Earth's history, Earth might have been spinning so fast that part of our planet spun off into space but was kept tethered by Earth's gravity.

2. Capture theory - The capture theory suggests that the moon originated elsewhere in the Milky Way, completely independent of Earth. Then, while traveling past Earth, the moon got trapped in our planet's gravity.

3. Co-accretion theory - Also known as the condensation theory, this hypothesis offers that the moon and the Earth formed together while orbiting a black hole.

4. Giant Impact hypothesis - [edited by UKT 180310] The reigning theory is that a Mars-sized object [a planetesimal] impacted with a very young, still-forming Earth [aka Gaia] about 4.5 Ga ago [ 4.5x10^9 yr ago]. [The impactor planetesimal has been dubbed "Theia" the daughter Moon-goddess Titaness (Hindu equiv Asura) Selene of Greek mythology, and the impactee is sometimes known as Gaia - the Earth-goddess Titaness (Hindu equiv Maata 'Mother' {mèý-tau}).
UKT 180312:
#1. When you are dealing with mythologies such as Burmese, Greek, Hindu, and Roman, make sure you differentiate déva, asura, {mèý-tau}, and {nût}, and their equivalents.
#2. Theia - https://en.wikipedia.org/wiki/Theia 180312
"... Theia (Ancient Greek Θεία),... also called Euryphaessa "wide-shining", is a Titaness".
#3. There are several challenges to the conventional Giant Impact hypothesis, one being both the impactor and impactee vaporised forming a giant torus, called synestia '
See also Giant Impact Hypothesis in Doubt by in UKT notes below.

Contents of this page

Titan Impact Hypothesis

UKT 180314: To differentiate the newer torus theory from the older conventional Giant Impact Hypothesis we should call it as the Titan Impact Hypothesis or the Impact of Titans Hypothesis.

See Wikipedia: https://en.wikipedia.org/wiki/Synestia 180312
"A synestia is a rapidly spinning donut-shaped mass of vaporized rock. In computer simulations of giant impacts of rotating objects a synestia can form if the total angular momentum is greater than the co-rotational limit. [1] Beyond the co-rotational limit the velocity at the equator of a body would exceed the orbital velocity. [2] In a synestia this results in an inner region rotating at a single rate with a loosely connected torus orbiting beyond it. [3]"

For Greek mythology Selene - not Roman - see:
- https://en.wikipedia.org/wiki/Selene 180311
"Selene, Ancient Greek Σελήνη 'Moon' is the Titaness of the Moon [In Hindu mythology Titan is Asura - an enemy of god Déva). Selene is the daughter of Titan parents Hyperion (father) and Theia (mother). Selene is sister of Sun Helios, sister of Dawn Eos

For Greek mythology - Gaia, see:
- https://en.wikipedia.org/wiki/Gaia 180311
(edited) "In Greek mythology, Gaia Ancient Greek Γαῖα, a poetical form of Γῆ , "land" or "earth" [1])"
I consider them to be just anthropomorphic entities.

My wish is not to belittle any religion whether ancient or modern. Our ancestors had worshipped them, and out of my respect for our forefathers, I consider them worshipping Axiomatic entities. To me, Gods and Titans of Ancient Greek and Roman religions are Axioms - not for me question whether they are real or not, just as I consider YHVH (Judaism), God (Christianity), and Allah (Islam) to be Axioms: they are all worshipfuls

There is another class of such entities in Bur-Myan beliefs and in Hinduism. They are the Mothers or Maatas, e.g. Mother-Myanmar {a.mi.mrûn-ma} representing Myanmarpré the country, and Bharat-Mata aka Mother-India representing the country of India. All living things on them - animals and humans, and, men and women of every faith and religion are their children.

Gaia is the Mother Earth [2] and one of the Greek primordial deities. She is the ancestral mother of all life: the primal Mother Earth goddess Wathondare {wa.þoan~da.ré}. Gautama Buddha called on her with his earth-touching posture (mudra) to stand as his witness for all the good-deeds he had done. Goddess Wathondare {wa.þoan~da.ré} by just pressing out the "water of libation in her hair, washed away the evil hosts of Mara.

When Theia hit Earth [Gaia], a portion of the planet [Gaia] came off and eventually hardened into the Moon. This theory does a better job than others of explaining the similarities in chemical compositions of the Earth and the Moon [from known samples of Lunar soil collected from Moon-landings of 1969 to 1976 by the US and Soviets], ... Theia could have been made of ice ... the giant impact hypothesis [ is just] -- a hypothesis. [How similar to mythologies! ]

See downloaded videos in TIL CD-VIDEO and SD-VIDEO libraries, section Geology remembering that they are just hypotheses.
- The History of the Earth: How our Planet formed - documentary
- HistEarth<Ô> / Bkp<Ô> (link chk 180310)
Note 180311: Only first part of the video has animation. It will be replaced by better ones.

UKT 180309: Being a history, we need to know its timescale in years, month and days. However, because what we are dealing here are long duration in time, we will start with "years", "thousands of year", "millions of year", and "billions of year". We'll therefore define the "year" first:
"A year is the orbital period of the Earth moving in its orbit around the Sun." - https://en.wikipedia.org/wiki/Year 180310
Wiki article on Year continues:
" SI prefix multipliers [SI units stands for Système international d'unités in French]:
" • ka (for kiloannus) -- a unit of time equal to one thousand, or 103, years, or 1 E3 yr, [or, 1x10^3 yr] ...
" • Ma (for megaannus) -- a unit of time equal to one million, or 106, years, or 1 E6 yr, [or, 1x10^6 yr] ...
" • Ga (for gigaannus) -- a unit of time equal to 109 years, or 1 E9 yr, one billion years, [or, 1x10^9 yr] ...
For example, the formation of the Earth occurred approximately 4.54 Ga (4.54 billion years) ago [or 4.54x10^9yr]."

Nearly all branches of natural science have contributed to the understanding of the main events of Earth's past. The age of the Earth is approximately one-third of the age of the universe. An immense amount of geological change has occurred in that timespan, accompanied by the emergence of life and its subsequent evolution.

Earth formed around 4.54 billion years ago by accretion from the solar nebula. [3] [4] [5] Volcanic outgassing probably created the primordial atmosphere and then the ocean, but the early atmosphere contained almost no oxygen O2 and so would not have supported known forms of life.[UKT ¶]

UKT 180312: The phrase known forms of life includes both aerobic and anaerobic forms. Since both aerobic and anaerobic bacteria are known, the phrase is not entirely correct. See Wikipedia:
- https://en.wikipedia.org/wiki/Anaerobic_organism 180312
"An anaerobic organism or anaerobe is any organism that does not require oxygen for growth. It may react negatively or even die if oxygen is present. (In contrast, an aerobic organism (aerobe) is an organism that can survive and grow in an oxygenated environment.)"

Much of the Earth was molten because of frequent collisions with other bodies which led to extreme volcanism. A giant impact collision with a planet-sized body named Theia while Earth was in its earliest stage, also known as Early Earth , is thought to have been responsible for forming the Moon. [UKT ¶]

UKT 180312: I've already said something of the giant impact collision in Giant Impact hypothesis . Though it is the most accepted view, it is still a hypothesis, being challenged again and again.

Over time, the Earth cooled, causing the formation of a solid crust, and allowing liquid water to exist on the surface.

The geological time scale (GTS) depicts the larger spans of time, from the beginning of the Earth to the present, and it chronicles some definitive events of Earth history. [UKT ¶]

UKT 180312: When we are speaking of the time-spans such as from the beginning of the Earth to the present , we have to define what we mean by the "beginning". Here we will take it as the Giant Impact hypothesis mentioned above. But still we are not certain, because after the Impact, did the smaller body which we will call the Moon just broke away, or was Synestia torus formed first, and only afterwards the outer part of the torus spun away to form the Moon?
See Wikipedia: https://en.wikipedia.org/wiki/Synestia 180312
"A synestia is a rapidly spinning donut-shaped mass of vaporized rock."

For my work I will take the beginning of the Earth as the time the Moon was formed. But you can still argue, "what will solidify into Earth may happen only afterwards."
See: https://ourplnt.com/moon-formation-synestia-theory/ 180312
"According to a new study, the Moon might has been formed a thousand years earlier than Earth. The new, “synestia theory” suggests a Mars-sized object smashed into the proto-Earth. The “giant impact” vaporized about 10 percent of the rock and liquefied the rest, and created a rapidly spinning donut-shaped mass of vaporized rock called “synestia”. The synestia eventually shrunk and cooled. Computer models demonstrated that the Earth subsequently emerged about 1,000 years after the moon."

The Hadean Eon represents time before the reliable (fossil) record of life beginning on Earth; it began with the formation of the planet and ended at 4.0 Ga ago as defined by international convention. [6] [UKT ¶]

UKT 180307: Though the above pix shows the Hadean Eon and Archean Eon without subdivisions of periods, there are speculated to have subdivision: See: TIL Hadeon Eon (4.6x10^6 to 4.0x10^6 ago)
- hadeon.htm (link chk 180307)
  • Pre-Nectarian, (4,533 to about 3,920 Ma ago.)
  • Nectarian (3,920 Ma to 3,850 Ma ago)
I like to view Hadean and Archean Eons together

The Hadian-Archean Eon pair is followed by Proterozoic Eon. The Archean-Proterozoic Eon pair produced the abiogenesis of life on Earth and then the evolution of early life. [UKT ¶]

UKT 180313: The Eons are separated from each other by defining events. See:
Geological time with major evolutionary events in the fossil record, by William L. Kruczynski and Pamela J. Fletcher, in Chapter 1, Geographic Setting and Impacts to the Environment ,
- WLKruczynskiPJFletcher-GeologTimeEvents<Ô> / Bkp<Ô> (link chk 180313)

From Pix on right: Major Events in:
1. Hadean Eon - Earth forms
2. Archean Eon - Oldest rocks, Earth crust forms
3. Proterozoic Eon - Life begins in sea

UKT 180314: You can easily get confused when you compare datelines from various websites. Look for the dividing line of 2500 Ma or 2.5 Ga., dividing between "only rocks" and "bacteria life in the form of blue-green" being formed.

The succeeding eon is the Phanerozoic Eon, which is represented by its three component eras: the Palaeozoic; the Mesozoic, and Cenozoic.  [UKT ¶]

The Palaeozoic Eon and the Mesozoic Eon spanned the rise, reign, and climactic extinction of the non-avian dinosaurs. [UKT ¶] .

The Cenozoic Eon presented the subsequent development of dominant mammals on Earth.

Hominins, the earliest direct ancestors of the human clade, rose sometime during the latter part of the Miocene Epoch; the precise time marking the first hominins is broadly debated over a current range of 13 to 4 million years ago. The succeeding Quaternary period is the time of recognizable humans, i.e., the genus Homo, but that period's two million-year-plus term of the recent times is too small to be visible at the scale of the GTS graphic. (Notes re the graphic: Ga means "billion years"; Ma, "million years".)

UKT: Hominins: - https://en.wikipedia.org/wiki/Hominini 180313
"The Hominini ("hominins") form a taxonomic tribe of the subfamily Homininae ("hominines"). Hominini includes genus Homo (humans), but excludes genus Gorilla (gorillas). There is at present (as of 2018 [update]) no consensus on whether it should include genus Pan (the chimpanzees), the question being closely tied to the complex speciation process connecting humans and chimpanzees and the development of bipedalism in proto-humans.

The earliest undisputed evidence of life on Earth dates at least from 3.5 billion years ago, [7] [8] [9] during the Eoarchean Era after a geological crust started to solidify following the earlier molten Hadean Eon. There are microbial mat fossils such as stromatolites found in 3.48 billion-year-old sandstone discovered in Western Australia. [10] [11] [12] Other early physical evidence of a biogenic substance is graphite [carbon atoms arranged in 2-dimensional layers] in 3.7 billion-year-old metasedimentary rocks discovered in southwestern Greenland [13] as well as "remains of biotic life" found in 4.1 billion-year-old rocks in Western Australia. [14] [15] According to one of the researchers, "If life arose relatively quickly on Earth … then it could be common in the universe." [14]

Photosynthetic organisms appeared between 3.2 and 2.4 billion years ago and began enriching the atmosphere with oxygen. Life remained mostly small and microscopic until about 580 million years ago or 0.58 Ga ago, when complex multicellular life arose, developed over time, and culminated in the Cambrian Explosion about 541 million years ago. This event drove a rapid diversification of life forms on Earth that produced most of the major phyla known today, and it marked the end of the Proterozoic Eon and the beginning of the Cambrian Period of the Paleozoic Era. More than 99 percent of all species, amounting to over five billion species, [16] that ever lived on Earth are estimated to be extinct. [17] [18] Estimates on the number of Earth's current species range from 10 million to 14 million, [19] of which about 1.2 million are documented, but over 86 percent have not been described. [20] Scientists recently reported that 1 trillion species are estimated to be on Earth currently with only one-thousandth of one percent described. [21]

The Earth's crust has constantly changed since its formation. Likewise, life has constantly changed since its first appearance. Species continue to evolve, taking on new forms, splitting into daughter species or going extinct in the process of adapting or dying in response to ever-changing physical environments. The process of plate tectonics continues to shape the Earth's continents and oceans and the life they harbor. Human activity is now a dominant force affecting global change, adversely affecting the biosphere, the Earth's surface, hydrosphere, and atmosphere, with the loss of wild lands, over-exploitation of the oceans, production of greenhouse gases, [an example being CO2 ], degradation of the ozone [ O3layer, and general degradation of soil, air, and water quality.

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In geochronology, time is generally measured in mya (megayears or million years ago), each unit representing the period of approximately 1,000,000 years in the past. The history of Earth is divided into four great Eons, starting 4,540 mya with the formation of the planet. Each Eon saw the most significant changes in Earth's composition, climate and life. Each Eon is subsequently divided into Eras, which in turn are divided into Periods, which are further divided into Epochs.

UKT 180314: I will continue working on this file sometime later.

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UKT notes

The Giant-Impact Hypothesis for the Moon’s Formation Is in Doubt

By on August 8, 2017 at 3:00 pm
- https://www.extremetech.com/extreme/253830-giant-impact-hypothesis-moon-formation-synestia#disqus_thread 180312
UKT 180315: "God and Goddess", the English translations of mythological entities usually misinterpret the meanings, because of which I have to edit the original article. In Hindu mythology (with equivalents in Greek and Roman) there are: Déva and Dévi; Asura and Asuri, and Maata 'Mother'. In English all have become "gods and goddesses", failing to note that Déva and Asura are enemies, and Maata 'Mother' is the anthropomorphic term for a country, an astronomical body, or even a prominent object. Maatas 'Mothers' is from Tib-Bur mythology taken over by the Hindu Brahmins {poaN~Na:}, mating them to their male gods. I need to clarify these terms for my work in connection with BEPS languages even when I am dealing with scientific disciplines such as Geology.

For decades, astronomers and scientists have relied on a theory of how the Earth-Moon system formed known as the Giant-impact hypothesis: A large chunk of rock nicknamed Theia (mother of Selene, 'Moon' in Greek mythology) slammed into the Earth not long after it formed. This impact would have liquefied both Theia and the Earth, while simultaneously ejecting a huge amount of material.

Impact of Titans : Theia (mother of Moon 'Selene') and Gaia 'Earth' giving birth to Moon.
   UKT 180115: Definitions from Greek mythology (edited): 
#1 - https://en.wikipedia.org/wiki/Selene 180311
  "Selene, Ancient Greek Σελήνη 'Moon' is the Titan-goddess of the Moon. Selene 'Moon' is the daughter of Titan father Hyperion and Titaness mother Theia. Selene is sister of Sun Helios, sister of Dawn Eos
#2 - https://en.wikipedia.org/wiki/Gaia 180311
   "Gaia, Ancient Greek Γαῖα aka Γῆ , 'Earth' or "land" [1])"
Note that it is a union of two females, one of which acts as the father giving birth to a daughter. In the act the mother dies. What a mess!

Over time, conventional thinking goes, the Earth cooled again and became rocky, while the huge lump of ejected rock formed the Moon. There’s even an explanation for why the Moon is thicker on one side than the other. A second, smaller moon may have briefly formed, before its orbit destabilized and it impacted on the far side of our own Moon.

The problem with the giant-impact hypothesis is it’s increasingly difficult to square with data. A new paper posits the conventional great impact hypothesis isn’t quite right, and argues for an entirely new theory of Earth-moon formation.

Let’s back up a moment and start with an uncontestable fact: The Moon -- our moon -- is quite odd. First, we’re the only rocky planet with a moon of significant size at all; Mercury and Venus have no moons, and the moons of Mars are either asteroids captured by that planet’s gravity or the remnants of a giant impact event that struck Mars in its own distant past. For example, Deimos, which orbits Mars, is little more than a dot, roughly as bright as Venus in our own sky.

UKT 180312: Wikipedia: https://en.wikipedia.org/wiki/Deimos_(moon) 180312
"Deimos (systematic designation: Mars II) [6] is the smaller and outer of the two natural satellites of the planet Mars, the other being Phobos. Deimos has a mean radius of 6.2 km (3.9 mi) [1] and takes 30.3 hours [1] to orbit Mars. In Greek mythology, Deimos is the twin brother of Phobos and anthropomorphic personified "terror".
"Deimos is 23,460 km (14,580 mi) from Mars, much farther than Mars's other moon, Phobos. [7]"
Note: Mars is the god of destruction, and therefore his sons are gods of terror.

The Moon is about 1 percent the mass of Earth, while the combined mass of all the moons of the outer planets is no more than one tenth of one percent of their parent planets. [UKT ¶] 

The Moon is also responsible for 80 percent of the angular momentum in the Earth-Moon system [a two-body system: to say that the Moon revolves around Earth is wrong - both revolves around the common center of mass.], while in the other planets, this value is less than 1 percent.  [UKT ¶] 

And unlike every other planet or satellite in the solar system, it appears to be made of exactly the same isotopes in the same ratios we observe on Earth.
That’s highly unusual in and of itself. As the early solar system formed, the lighter isotopes were dispersed by stellar wind, explaining why the inner planets are rocky while the outer planets are gas giants and so-called ice giants (Uranus, Neptune, and the still-hypothetical Planet IX). Each of the planets and satellites contains its own unique mixture of isotopic ratios, which is why we can sometimes identify the origins of various meteorites; a meteorite from Mars has a distinctly different isotopic ratio than a meteor from the asteroid belt.

The problem with the giant-impact hypothesis is that it has difficulty accounting for why the isotopic ratios on the moon look exactly like the ones we see on Earth. Over at The Atlantic, Rebecca Boyle steps through the various potential options, including new work by scientist Sarah Stewart and her student, Simon Lock. Stewart and Lock have offered an intriguing option that posits a new idea for how the Earth and moon may have coalesced after a massive impact. They propose Theia struck the Earth and thoroughly vaporized it, forming a torus of molten rock and vaporized material. As the lava-bagel spun, the outer edge moved much more quickly than the inner region, and never completely differentiated from it. They’ve named this hypothetical structure a synestia, syn from the Greek “together” and Hestia, the Greek goddess of the home, hearth, and architecture.

The inner, rocky planet eventually became the Earth, while the faster-moving cloud of vaporized rock coalesced into the Moon. This explains both the high conservation of angular momentum and the isotope mixing, though this is a still a theoretical model and not one we’ve observed in the real-world to date. Then again, our data on planetary formation is still extremely limited. We’ve directly observed geologic activity on Mercury and captured planets in the process of forming around a distant star, but this kind of impact and mixing is far more difficult to see, particularly around a planet as small as ours to start with.

A synestia isn’t the only way to theoretically create an Earth-Moon system. Rebecca Boyle steps through some other hypotheses, including the idea that Theia was a body with near-identical isotope ratios to Earth to start with, or that the Earth may have been subject to multiple large impacts that collectively broke off and mixed enough material to create the Moon. Given our lack of time travel, it may not be a theory we can ever test. Then again, spacecraft like Kepler have pushed back the boundaries of observed astronomy by leaps and bounds, confirming some of our ideas about how planets and stars form and disrupting others.

It’s entirely possible that if we keep an eye out (and keep building bigger telescopes) we will catch the above process in action around a different star. To be sure, most of these new ideas are variants on the standard giant-impact hypothesis, not wholesale repudiations of it. But they still represent several challenges to the conventional explanation.

UKT: End of article.

Go back Giant-Impact-Hypo-Doubt-note-b


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