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Pertemuan ke-2 The big bang theory The Origin of the Ea its Oceans and Life the Oceans (Asal-usul bumi, laut dan kehidupan d 1 Course Outline 1. The Origin of the Cosmos (Universe) a. The Galaxies and Stars b. The Elements 2. The Sun and the Solar System 3. The Origins of the Earth a. The Geological Time Scale b. The Origin of the Oceans and Atmosphere c. The Original Continents d. The Moon e. Life Form in asalod the Oceans 2 Hubble Space Telescope asalod 3 Quintuplet Cluster Neutron Star Magnetar Messier asalod Dying Star 4 Beberapa Istilah: • Star (bintang): ‘bola’ (sphere) masiv berupa gas pijar (terlihat banyak di angkasa) • Galaxy: Kumpulan bintang, debu, gas dan debu angkasa lainnya yang berotasi dan berada bersama oleh gaya tarik gravitasi. • Universe atau cosmos (cakrawala): kumpulan galaxy. Kira2 terdapat 100 juta galaxy yang teramati dg teleskop kita. • Planet berada satu sistem dengan bintang dan bergerak mengitarinya • Satelit, benda angkasa yang mengelilingi planet, mis. Bulan. • 1 Tahun Cahaya: Kec. asalod cahaya (~3.105 km/s) x 1 tahun5 12 Galaxy Milky Way • Galaxy dimana tata surya kita berada) • diameter cakram: 100,000 tahun cahaya (TC); tebal cakram 10,000-15,000 TC • Tata surya beserta ke-9 planetnya berada sekitar 2/3 dari sisi luar Galaxy ini. • Tata surya mengikuti pergerakan Galaxy MW dengan kec. ~ 280 km/s • di dalam Galaxy MW terdapat ~1011 bintang, yg mana puluhan juta binang itu memiliki planet dan makhluknya. asalod 6 Tata Surya (Solar System) a. Ukuran relatif planet dan surya a. Orbit planet dari Tata Surya asalod • 9 planet • Terdekat: Merkurius •Terjauh: Pluto Planet yang terdekat dgn mthari lebih kecil Karena emisi partikel dari mthari yg terionisasi dan pemanasan internal planet itu 7 sendiri Dengan mengamati energi cahaya yang memancar dari galaxy, astronomer mampu menentukan bahwa hampir semua galaxy sedang menjauhi satu sama lainnya, pada kecepatan ~240,000 km/s (3/4 kec cahaya !). Saling menjauhnya galaxy 2 tersebut diduga sebagai serpihan2 hasil dari suatu ledakan, yang berasal dari satu massa yang sama. Jika hal ini sebagai kenyataan, waktu yang diperlukan dari ledakan tsb sampai keadaan saat ini adalah ~15 milyar tahun. asalod Big Bang Theory 8 The Origin of the Universe The Big Bang Theory is the prevailing scientific explanation of the origin of the universe. This theory proposes that at one time all matter was concentrated into a single, extremely dense body. Then about 15 billion years ago, a tremendous explosion sent this matter hurling outward into space. asalod 1 billion=109 9 Dasar Utama • Energi cahaya yang hasil radiasi galaxi, makin jauh makin rendah energi (shifting spektrum) • Galaxi saling menjauhi karena ada ledakan • Apa semua pernah berkumpul, tidak pasti? • Waktu untuk sampai posisi sekarang ~15 miliar thn asalod 10 Timeline of the Big Bang asalod 11 THE COMPETITORS … FOR THE THEORY ON ORIGIN OF THE UNIVERSE • The Bubble Universe / Andre Linde's Self Creating Universe • The Inflationary Theory (1981, Alan Guth ) • The Proto-universe (white hole theory) • The Steady State Theory (late 1940’s asalod 12 Formation of the Elements Within minutes, the universe expanded to an enormous size and cooled enough to allow protons and neutrons to fuse together to form atomic nuclei, a process known as nucleo-synthesis. Within just one day’s time, nucleosynthesis produced nearly all of the hydrogen and helium nuclei in existence today. Hydrogen and helium are the lightest and most abundant elements in the asalod universe. Heavier elements account for only about 0.1% of all the elements in the 13 universe. Evidences for the Big Bang • Galaxies are moving away from us at speeds proportional to their distance. This is called "Hubble's Law," named after Edwin Hubble (1889-1953) who discovered this phenomenon in 1929 • The abundance of the "light elements" Hydrogen and Helium found in the observable universe are thought to support the Big Bang model of origins • Cosmic Background asalod Radiation predicted by14 Expanding Universe The early universe continued to expand like a cloud of hot gases. Over the next billion years, gravity compressed pockets of these gases into the first stars and galaxies. 15 asalod 16 Galaxies and Stars A star is a massive sphere of incandescent gases (gas pijar). A galaxy is a rotating collection of stars, dust, gas, and other interstellar debris held together by gravitational attraction. The universe may contain as many as 50 billion galaxies, each with nearly 50 billion stars asalod 17 asalod 18 Production of Heavier Elements • Most stars “burn” hydrogen to produce helium and energy. Four hydrogen atoms fuse to form a helium atom. • In this process a small amount of matter is converted into a vast amount of energy. • After a star has burned most of its hydrogen, it collapses. • If it is large enough, the collapsed star then burns helium, forming the heavier elements of carbon and oxygen. • Red giants (massive stars) undergo this cycle of fuel burning/collapse several times, forming silicon, magnesium, asalod 19 and heavier elements. Supernovas • When all of a large star’s fuel is consumed, it undergoes a final sudden collapse, then explodes violently in a supernova, propelling much of its matter into space. • The force of the supernova produces neutrons that collide with other atoms from the exploding star to form the heavier elements, which are thrust into space to become part of the interstellar dust. asalod 20 Origin of the Solar System • The sun and the planets of the solar system have a common origin, all coalescing from the solar nebula, a rotating cloud of interstellar dust and gas enriched with heavy elements released by supernovas. • The rotation of the nebula caused it to flatten, and gravity contracted the material near the center into a protosun. • Material farther from the center accumulated into the planets. asalod 21 The Solar Wind • Once the internal temperature of the protosun increased to the point where hydrogen atoms fused into helium, it became the sun. • The intense solar wind produced when the sun “lit” swept most of the gaseous elements out of the inner solar system. • The elements that remained to form the Earth were oxygen (mostly bound to metals), silicon, iron, aluminum, calcium, magnesium, sodium, and potassium, the elements that constitute most of the rocks found on the Earth today. asalod 22 The Evolution of Earth Our planet accumulated from the interstellar material by accretion. Centimeter-sized particles and gases condensed into kilometer-scale planetesimals (small proto-planets). The planetesimals were drawn together by gravity and fused into a planet. asalod 23 Differentiation of the Earth’s Interior • The earth’s original composition was uniform throughout. • Late in the accretion stage, frequent collisions with meteors and other debris from outer space caused the surface of the planet to heat up. • Additional heating from the decay of radioactive elements within the earth caused the whole planet to melt! • Gravity pulled the heavy iron inward to form the mantle and core. • Lighter materials of silicon, magnesium, aluminum, and oxygen-bonded compounds migrated upward. • About 4.6 billion years ago, the first hard surfaces crystallized asalod into the crust. 24 The Geologic Time Scale • Scientists have detailed the Earth’s history dating back 4.6 billion years in the Geologic Time Scale. • This scale is divided into a hierarchical set of increasingly smaller units of time, such as eons, eras, periods, epochs, and ages. asalod 25 asalod 26 asalod 27 • The Early The atmosphere began to form about 4.4 billion years ago Atmosphere during the Precambrian period. • Frequent volcanic eruptions and earthquakes allowed carbon dioxide, nitrogen, and other gases trapped inside the planet to escape (outgas) and form the atmosphere. • The degassing of comets plunging to the earth’s surface also released quantities of ammonia, methane, and water vapor into the atmosphere. asalod 28 Composition of the Atmosphere • The levels of carbon dioxide were as much as 1,000 times present levels. • Because oxygen rapidly bonded to metals in the crust to form oxides, like the rusting of iron, there was no oxygen present in the early atmosphere. • Water vapor was so abundant in the primordial atmosphere from out gassing that the atmospheric pressure was several times greater than today. asalod 29 • Suns energy stripped away 1st atmosphere • 2nd atmosphere formed from volcanic out gassing • Primitive atmosphere: CO2, water vapor, lesser atms of CO, N2, H2, HCl, and traces of NH3 and CH4 (3.5 billion year ago) asalod 30 The Blue Planet • After several million years, the atmosphere cooled sufficiently to allow the water vapor to condense into thick clouds which cloaked the entire planet. • Rain began to fall from the sky, cooling the • surface. Rainwater collected in craters and basins, where it evaporated, cooled and again.of heavy rains • fell A period deluged the planet for some 10 million years. • When the rains ceased and the skies cleared, the Earth emerged as a blue planet carpeted by an asalod ocean almost two miles 31 Formation of Earth’s Oc • Off gassing of water vapor from volcano • Condensation • Rain asalod 32 The Continents • Originally, there was little, if any, continental land mass. • Underlying the sea is a layer of oceanic crust about 8 km thick, primarily composed of basalt, a dense, iron-rich rock of volcanic origin. • Continental crust is thicker (20–70 km), and typically composed of lighter, granitic rock distilled from the repeated recycling of mantle material and oceanic crust (a process in the nextcrust lesson). • discussed The first continental probably came into existence at a few isolated island arcs and has accumulated over time into the large land masses we know today. • Explanations describing the origin and evolution of the continents are still highly speculative. asalod 33 The First Supercontinent • By the end of the Precambrian period, approximately 700 million years ago, all land masses had gathered into the single supercontinent Rodinia, surrounded by the Panthalassic Ocean. asalod 34 The Moon • Ocean tides are a primarily a result of an interplay of forces between the Earth and the Moon. The leading theory of the Moon’s origin is the giant impact hypothesis. At the time Earth formed, other smaller planetary bodies were also growing nearby. One of these bodies, about 1/3 to 1/2 the size of Earth, struck the Earth late in its growth process. Debris from that collision went into orbit around the Earth and aggregated into the moon. asalod 35 The Moon and the Earth • The Moon, the largest in the solar system relative to its mother planet, may have stabilized the tilt of the planet’s rotational axis that produces the seasons. • Without the Moon, Earth might experience the extreme and hostile fluctuations in weather and climate observed on Mars. asalod 36 Origin of life • Life began~ 3.5 billion-year-ago (bya) • Organic molecules (C H O N P S) swimming in shallow seas Stage 1: Abiotic synthesis of organic molecules such as proteins, amino acids and nucleotides asalod 37 Stage 2: joining of small molecules (monomers) into large molecules asalod 38 Stage 3: origin of self-replicating molecules that eventually made inheritance possible asalod 39 Stage 4: packaging these molecules into pre-cells, droplets of molecules with membranes that maintained an internal chemistry asalod 40 Thomas Huxley- Search for origin of life Bathybiasheckalii- primordial ooze (sedimen yg lunak) Wyville Thompson: HMS Challenger (18721876) found it was actually diatomacous ooze reacting with seawater and ethyl alcohol Also, disproved Forbes’ Azoic Theory (18681870) asalod 41 Miller & Urey (1953)- mixed water vapor, NH3, CH4, H2 + electric spark amino acids and other organic compounds Synthesis of Organic Molecules electrodes Methane, ammonia, and hydrogen added CH4 NH3 H2 water vapor spark condenser boiling water water containing organic compounds 42 Produced: • • • • 20 amino acids Several sugars Lipids Purine and pyrimidine bases (found in DNA, RNA & ATP) asalod 43 chemosynthetic bacteria (extremophiles) Chemosynthesis: 02 + 4H2S + C02 CH20 + 4S +3H20 Stromatolites (bacteria &cyanobacteria) Oldest fossils found in western Australia and southern Africa ~ 3.5 bya Photosynthesis: 6H2O + 6CO2 + nutrients + light energy asalod C6H12O6 + 6O2 44 mostly cyano Stromatolites from Shark’s Bay Australia asalod 45 asalod 46 PANSPERMIA THEORY Organic compounds arrived from outer space It states that hydrocarbons and other organic molecules (molecules that organisms contain or that might lead to the genesis of life) have been found in meteorites – It means that at least prebiotic chemistry that leads to the primordial soup might be going on there. asalod 47 Evidences in support of this theory • In 1969, a meteorite landed in Australia that was 12% water and contained traces of 92 amino acids. • It points to not only the presence of organic compounds in outer space, but also the capacity of such compounds to reach earth. • Fred Hoyle and Chandra Wickramasinghe have argued persistently since the 1970s that complex organic substances, and perhaps even primitive organisms, might have evolved on the surface of comic dust grains in space and then been transported to the Earth's surface by comets and meteorites. asalod 48 Where did life begin ??? • There is an ongoing debate regarding the most probable site of life's origins. • The prevailing paradigm - life began near the ocean's surface, bathed in sunlight. • Current Research - life arose near deep hydrothermal vents which is still under investigation. "Scientists have long suspected that life on Earth originated in the ocean and strong evidence now suggests that the earliest life on our planet occurred in the depths of the ocean in the absence of heat and light." -- Pulse of the Planet, American Museum of Natural History asalod 49 asalod Photograph from National Geographic magazine 50 Deep-sea Vents • Their discovery in late 1970’s stretched our concept of the origin of life on earth. • Can life exist and that too thousands of meters beneath the surface of sea in absence of sunlight? • It raised the possibility that earlier vents supplied the energy and chemical precursors for origin of protobionts. asalod 51 Exploring the deep ocean floor View of the first hightemperature vent (380°C) ever seen by scientists during a dive of the deep-sea submersible Alvin in 1979. Such geothermal vents are called smokers. asalod This photograph shows a black smoker, but smokers can also be white, grey, or clear depending on the material being ejected. Photograph by Dudley Foster from RISE52 expedition Vent Community A vent community in its prime: Pale pink eelpout fish and white brachyuran crabs swim and scuttle among blood-red tube worms large and small. Scientists are still trying to figure out how the offspring of such organisms disperse over long stretches of inhospitable seafloor to 53 colonize widely separated vent systems. Giant Clams The size of deep-sea giant clams is evident from the hands of a scientist holding them. (Photograph by William R. Normark, USGS.) 54 Giant Tube Worms: RIFTIA • On the bottom of the ocean around deep-sea hydrothermal vents, there is a profusion of life that thrives on the hydrogen sulfide (H2S) gas released from the vents, and live inside hard, shelllike protective tubes that attach Giant tubeworms that live around hydrothermal vents on the sea floor. These creatures are about the size of your hand in shallower waters, but in the ocean's deep they have been found as big as eight feet long! 55 How they live…. • These creatures lack mouths, anuses, intestines and stomachs, and scientists were at a loss to explain how these were getting nutrients to survive and grow. • Their insides are lined with bacteria that oxidize the H2S, turning it into usable nutrients for the worms. • The bacteria, in turn, benefit from the relationship because the worms deliver blood containing hemoglobin which helps the bacteria to break down the sulfides. • They live in a symbiotic relationship with a bacteria that may hold clues as to how life on earth began 56 BIOCHEMISTRY AT THE VENTS • H 2S Released from vents Oxidation by bacteria Energy released helps in fixing CO2 into small organic molecules So this cycle ... is the same metabolic pathway that is utilized by plants in photosynthesis takes inorganic carbon dioxide and fixes it into organic compounds that are then food. But, the critical difference, is that rather than using sunlight, these animals and bacteria are completely independent of sunlight. They utilize chemical energy to power that reaction. 57 So, ever imagined a life out of toxic Hydrogen Sulphide Chemical of Life - Ammonia, Produced at Vents • Hydrothermal vents were the most likely site for NH3 production where inorganic sulphides acted as catalyst. N2 +NO2 +N03 Presumed to be present in ancient sea FeO 46% yield 15 min FeS, 500oC Powdered Basalt. 20% yield 89% yield, 15 min NH3 Stable upto 800oC 58 RESULTS • Since NH3 cannot survive at temperature above 800oC indicates that nitrogen would have been present only as N2 during early phase of earth’s development. • Life can exist on thermal and chemical energy as opposed to just sunlight as had been thought in the past. And so what was realized is that photosynthesis was not the only way to support life. asalod 59 asalod 62 asalod 63 asalod 64