ธรรมชาติบางครั้งก็ทำลายตัวเอง เป็นผลจากการเรียงตัวของดาวและแกแล็คซี่ที่ส่งผลต่อดวงอาทิตย์(การเกิดขึ้น ขยายตัว และการระเบิดของจุดดับบนดวงอาทิตย์) และเมื่อพลังงานจากดวงอาทิตย์เดินทางมาถึงโลก ก็ส่งผลกระทบต่อโลก ทำให้เกิดการก่อตัวของพายุ แผ่นดินไหว หรือพายุแม่เหล็ก เป็นต้น
พลังงานที่เกิดจากการระเบิดของหลุมดำแพร่กระจายออกไปในทิศทางต่างๆ บางส่วนก็ส่งผลกระทบต่อโลกโดยตรง มากบ้าง น้อยบ้าง
แต่ละพื้นที่ได้รับผลกระทบมากบ้างน้อยบ้างแตกต่างกันไป รวมถึงส่งผลต่อระดับอุณหภูมิ ณ พื้นที่ต่างๆบนพื้นโลก
ผมเดาว่าน่าจะเกี่ยวข้องกับแรงดึงดูดที่มีต่อระดับฮอร์โมนสำคัญในร่างกาย ส่งผลให้เรารู้สึกสบายหรืออึดอัดหงุดหงิด แล้วส่งผลต่อมายังพฤติกรรมการแสดงออก โดยที่คนแต่ละธาตุ แต่ละกรุ๊ปเลือดนั้นมีสัดส่วนของธาตุทั้ง ๔ และความไวต่อสิ่งแวดล้อมแตกต่างกัน จึงส่งผลกระทบต่อนิสัยใจคอของคนแตกต่างกัน เท็จจริงเป็นอย่างไรคงต้องรอให้มีนักวิทยาศาสตร์หันมาสนใจ ทำเครื่องมือวัดหาความเชื่อมโยงระหว่างดวงดาว แรงดึงดูด สนามแม่เหล็กกับผลกระทบต่อร่างกาย อารมณ์ ระดับฮอร์โมนกันต่อไป
http://www.bbc.co.uk/nature/history_of_the_earth กล่าวถึงหายนะภัยครั้งใหญ่บนผืนภิภพในอดีตที่ผ่านมาว่ามี ๕ ครั้ง
History of life on Earth
The Earth is a little over 4.5 billion years old, its oldest materials being 4.3 billion-year-old zircon crystals. Its earliest times were geologically violent, and it suffered constant bombardment from meteorites. When this ended, the Earth cooled and its surface solidified to a crust – the first solid rocks. There were no continents as yet, just a global ocean peppered with small islands. Erosion, sedimentation and volcanic activity – possibly assisted by more meteor impacts – eventually created small proto-continents which grew until they reached roughly their current size 2.5 billion years ago. The continents have since repeatedly collided and been torn apart, so maps of Earth in the distant past are quite different to today’s.
The history of life on Earth began about 3.8 billion years ago, initially with single-celled prokaryotic cells, such as bacteria. Multicellular life evolved over a billion years later and it’s only in the last 570 million years that the kind of life forms we are familiar with began to evolve, starting with arthropods, followed by fish 530 million years ago (Ma), land plants 475Ma and forests 385Ma. Mammals didn’t evolve until 200Ma and our own species, Homo sapiens, only 200,000 years ago. So humans have been around for a mere 0.004% of the Earth’s history.
During its dramatic 4.5 billion year history, Earth has gone through a series of major geological and biological changes. The timescale below highlights a number of notable prehistoric events and the geological periods in which they occurred. As things didn’t get interesting from a biological perspective until around 570 million years ago, we’ve included a couple of zoomed in timelines to show the detail of more recent evolutionary history. Showtext only timeline
Geological time periods
Geologists have organised the history of the Earth into a timescale on which large chunks of time are called periods and smaller ones called epochs. Each period is separated by a major geological or palaeontological event, such as the mass extinction of the dinosaurs which occurred at the boundary between the Cretaceous period and the Paleocene epoch.
- Archean era3.8 billion–2.5 billion years ago
- Cryogenian period850 million–635 million years ago
- Ediacaran period635 million–545 million years ago
- Cambrian period545 million–495 million years ago
- Ordovician period495 million–443 million years ago
- Silurian period443 million–417 million years ago
- Devonian period417 million–354 million years ago
- Carboniferous period354 million–290 million years ago
- Permian period290 million–248 million years ago
- Triassic period248 million–205 million years ago
- Jurassic period205 million–142 million years ago
- Cretaceous period142 million–65 million years ago
- Palaeocene epoch65 million–54.8 million years ago
- Eocene epoch54.8 million–33.7 million years ago
- Oligocene epoch33.7 million–23.8 million years ago
- Miocene epoch23.8 million–5.3 million years ago
- Pliocene epoch5.3 million–2.6 million years ago
- Pleistocene epoch2.6 million–11.7 thousand years ago
- Holocene epoch11.7 thousand years ago–present day
Although the Cretaceous-Tertiary (or K-T) extinction event is the most well-known because it wiped out the dinosaurs, a series of other mass extinction events has occurred throughout the history of the Earth, some even more devastating than K-T. Mass extinctions are periods in Earth’s history when abnormally large numbers of species die out simultaneously or within a limited time frame. The most severe occurred at the end of the Permian period when 96% of all species perished. This along with K-T are two of the Big Five mass extinctions, each of which wiped out at least half of all species. Many smaller scale mass extinctions have occurred, indeed the disappearance of many animals and plants at the hands of man in prehistoric, historic and modern times will eventually show up in the fossil record as mass extinctions. Discover more about Earth’s major extinction events below.
- Ordovician-Silurian mass extinction443 million years ago
- Late Devonian mass extinction359 million years ago
- Permian mass extinction248 million years ago
- Triassic-Jurassic mass extinction200 million years ago
- Cretaceous-Tertiary mass extinction65 million years ago
Asteroid impacts, climate change, volcanoes – there have been many theories about the causes of mass extinctions. In some cases, such as the Cretaceous mass extinction event, more than one such factor was involved in the global catastrophe.
If you were able to travel back far in time, you’d find Earth to be a very different place – at times a giant hot molten ball of rock, at others a frozen planet completely covered in snow and ice. During its long history, Earth has been covered by habitats and experienced climates that no longer exist. Discover more about these and about the dramatic story of ancient Earth.
http://listverse.com/2012/03/09/top-10-mass-extinctions/ จัดอันดับหายนะภัย ๑๐ อันดับไว้ดังนี้
Top 10 Mass Extinctions
During the Ediacaran period, complex life had begun to take form for the first time on Earth. Tiny bacteria had evolved into the more complex and specialized Eukaryotes, some of which grouped together to increase their chances of finding food and avoiding becoming food. Most of these odd creatures did not leave a record because they had no skeletons; they were soft and tended to rot when they died rather than fossilize. Only in peculiar circumstances could fossils form, such as a creature lying on soft mud which suddenly hardened and left an imprint. These few fossils tell us of seas full of strange and alien creatures who resembled modern worms, sponges, and jellies. However, these creatures were dependent upon oxygen, as are we. The oxygen levels began to fall and world-wide extinctions occurred 542 million years ago. Over 50% of all species died. The huge numbers of dead creatures decomposed and make up some of today’s fossil fuels. The exact cause of the lowering oxygen levels is unknown, however, this mass extinction made room for the Cambrian explosion, a sudden diversifying of complex creatures beyond mere worms.
During the Cambrian period, life flourished. The Edicaran life had remained largely unchanged for millions of years, but in the Cambrian it suddenly diversified and evolved into endless new forms. Exotic crustaceans and trilobites became the dominant life in their huge numbers and variety. Shellfish and giant aquatic arthropods, similar to insects, filled the seas. These creatures had rigid exoskeletons which left a bounty of fossils for us to study. Life flourished until, rather suddenly in geological terms, over 40% of all species suddenly became extinct 488 million years ago. Those that remained survived poorly at best due to some harsh change in the environment. What this change was we do not know. One theory is that a glaciation occurred, the coldest part of an ice age. We have been enjoying an interglacial period, the warmest part of an ice age, for the past eleven thousand years. An extreme change in temperature can easily cause the extinction of a huge amount of life. This extinction event marked the border between the Cambrian and Ordovician periods.
Life began to flourish once again during the Ordovician period. Nautiloids (primitive octopuses), trilobites, corals, starfish, eels, and jawed fish filled the seas. Plants were struggling to take hold on land. Life was gradually becoming more complex. 443 million years ago, over 60% of life died out in what is considered the second largest extinction on record. It was caused by a rapid ice age brought on by lowering levels of carbon dioxide. Much of the water that was home to the abundance of life became used up in icecaps and glaciers which in turn caused oxygen levels to lower as well. It is thought that a burst of gamma rays from space had destroyed the ozone layer and the Sun’s unfiltered ultra-violet radiation then destroyed much of the plant life, which caused the initial drop in carbon dioxide. Although some life survived and continued on, by number of species it would take over 300 million years to recover from this event.
Following the Ordovician extinction, the Silurian period began. Life recovered from the last mass extinction and this period was marked by the development of true sharks and bony fish, most of which appeared perfectly modern. Moss and small plants finally began to grow freely on land along coastlines, and some arthropods evolved into spiders and millipedes who were adapted to the dry air and lived alongside the land plants. Enormous sea scorpions became abundant, and trilobites continued to dominate. 420 million years ago, there was a sudden climate change which caused the extinction of perhaps 30% of all species. The atmospheric gases changed in proportions that many creatures found disagreeable or toxic. The cause of this change is not known. Life struggled on until the Silurian period ended and the Denovian period began, when evolution produced a different model of life that thrived.
The Devonian period was where certain fish evolved sturdy fins that let them crawl onto dry land, eventually becoming animals such as reptiles and amphibians. In the seas, vast coral reefs were filled with fish and sharks, some of whom ate trilobites. The trilobites lost their footing as a dominant sea creature for the first time since they appeared over 100 million years prior. In fact, the sharks of this time were so successful that they have not needed to change much and some modern sharks look almost exactly the same as their predecessors. Land plants evolved seeds and diversified. More complex land plants developed and soil appeared for the first time in history. Strange forests of 8m tall fungi sprouted, which sadly are no longer with us. 374 million years ago, 75% of all this amazing life died out. This was due to a change in atmospheric gases, possibly due to massive volcanic activity or a meteorite impact.
After the Devonian period came the carboniferous period. A few land animals developed terrestrial eggs, which allowed them to live almost anywhere on land rather than being confined to shores where they could lay their eggs, as turtles still do today. Winged insects appeared and prospered. Sharks enjoyed a golden age and the few trilobites who had survived the last extinction became increasingly rare. Gigantic trees appeared and vast rain forests covered much of the land, increasing the air oxygen content to 35%. For comparison, today 21% of the air is oxygen. Conifers from the Carboniferous period remain almost unchanged today. 305 million years ago, a short sudden ice age caused carbon dioxide levels to become the lowest in the known history of Earth. The great forests died and with them, many of the land animals. Nearly 10% of all the species on Earth disappeared at this time. The trees rotted, condensed, and are now our main source of carbon fuels, after which this period was named.
After the rain forests fell, the most successful animals left on land were those who laid eggs. These quickly dominated before other species had a chance to recover and they diversified, producing a huge variety of reptiles and dominant synapsids, which were mammal-like reptiles and the ancestors of mammals. 252 million years ago, a disaster occurred which the Earth had never seen before and has never seen since. It was caused by a meteorite impact or volcanic activity which changed the air composition radically. Between 90% and 99% of all life became extinct. This is the biggest mass extinction in history, and is known as the â€˜Great Dying’.
For reference, let us look at the extinction of animals caused by humans. During our tenure, high estimates suggest that we have wiped out nearly 1000 species of animal. There are about 8 million species alive today, meaning that even according to the most pessimistic estimates, we have obliterated 0.01% of all animal life. Although this is nothing to be proud of, it is infinitesimal when compared to the gargantuan extinctions nature herself casually puts forward.
After the desolation caused by the end of the Permian period, reptiles again became dominant and the dinosaurs appeared. Dinosaurs were not dominant above other reptiles, and at this stage were not much larger than horses. It was their descendants who became the famous and fearful creatures we know so well. All the larger dinosaurs, tyrannosaurus, stegosaurus, triceratops, and the giant long-necked sauropods, came in the Jurassic or the Cretaceous periods. 205 million years ago, 65% of Triassic life died out, including all the large land animals. Many of the dinosaurs were spared due to their small size. Most mass extinctions last a million years or so, but this one took only ten thousand years. It was likely caused by massive volcano eruptions which disgorged huge amounts of carbon dioxide or sulphur dioxide, resulting in sudden climate change.
During the Jurassic period, gigantic sea reptiles such as the famous plesiosaur dominated the oceans. Pterosaurs ruled the skies and dinosaurs ruled the land. Stegosaurus, the long diplodocus, and the great hunter allosaurus became common. Conifers, cycads, ginkgoes, and ferns provided lush forests. Smaller dinosaurs evolved feathers and birds began to appear. 200 million years ago, 20% of life suddenly vanishes from the fossil records, mostly marine species. Shellfish and corals had been widespread, yet they almost completely vanished. The few who survived managed to repopulate the seas gradually over the coming millions of years. This extinction did not greatly affect land animals, and only a few species of dinosaurs were lost. The cause of this almost marine-exclusive extinction is a matter of debate, but one possibility is that the ocean tectonic plates sank slightly and made the oceans deeper. Most marine life was adapted for shallow water, and it perished as it crept further and further away from the surface.
This is the most famous extinction event. After the Jurassic ended, dinosaurs continued to proliferate and evolve throughout the subsequent Cretaceous period. They specialized into the forms which are familiar to many children today. More importantly, it was only during the Cretaceous period that life finally recovered from the much earlier Ordovician-Silurian extinction. The number of species at last matched and then exceeded the number from the Ordovician period, over 300 million years prior, for the first time. The synapsids finally evolved into small, rodent-like creatures, which were the first true mammals. 65 million years ago, a huge meteorite impacted the earth at Chicxulub in modern Mexico, disrupting the atmosphere and causing severe global warming, in turn killing 75% of all species. This meteorite contained a high concentration of iridium, normally rare on Earth, and all around the world rocks which are 65 million years old show a thin layer of iridium left over from the impact. A few small reptiles and mammals were among the survivors of this extinction. Mammals would go on to replace dinosaurs as the dominant terrestrial animal.