Quarter 1-2 Earth & Space

ORIGIN OF THE UNIVERSE:

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Absolute magnitude: The brightness of a star from a standard distance.

Apparent magnitude: The brightness of a star as seen from Earth.

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90% of stars: Are in the main sequence, the longest phase of a star’s life.

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Supernovas takeaway: They’re the death explosion of stars. Supernovas scatter gas and matter into space; these materials become nebula and eventually new stars over time.

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Creation of a supernova: When a large star becomes unstable, a supernova begins to develop. The core will become too heavy and collapse (implode) in itself, creating a massive explosion that results in a supernova. \n

Due to the vast distances in the universe, we see the light of supernova years and years after the star’s death. \n

How color reveals the temperature of a star:

Blue - Hottest

White

Yellow

Red-orange

Red \n

Steady State Theory: Introduced by Sir James Jeans in 1920. It stated that there are no beginnings or endings to the universe. The universe is still expanding but maintains a constant average density. The matter is continuously created to form new galaxies and stars at the same rate old galaxies and stars are disappearing.

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Big Bang Theory: Prior to the beginning, there was nothing. The universe is estimated to exist between 15-20 billion years as an infinitesimally small, infinitely hot, infinitely dense something. Which turns out to be a singularity. Singularities are zones that defy our current understanding of physics. It’s believed that they exist at the center of a black hole. After the singularity’s appearance, it expands and rapidly cools down, creating our universe.

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Evidence for the Big Bang:

Hubble’s law: Galaxies are moving away from us at a speed proportional to their distance.

Cosmic microwave background radiation: Leftover heat from the Big Bang

The abundance of light elements, hydrogen, and helium found in our universe \n

The ultimate fate of an open universe: The universe will continue to expand forever. All stars will eventually use up their energy and burn out. The universe will be cold and dead forever.

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The ultimate fate of a closed universe:The expansion will begin to slow until the gravitational attraction of the matter forces the universe to reverse and collapse upon itself (Big Crunch theory). This might lead to another Big Bang or universe in the future. The amount of dark matter will determine the fate of the universe. \n

Redshift: Redshift observation shows that distant galaxies are moving away from Earth (caused by the Doppler effect). \n

How the Doppler effect applies to light: The Doppler effect changes the color spectrum of the light. If the stars are moving farther away from us it's called a redshift. Away from is blueshift.

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STARS

• Scientists use LIGHT YEARS to measure distances in space. A light year is the distance light travels in one year.
• Light travels at the speed of 300,000 km/second.
• Light will travel 9.5 million, million kilometers in one year

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Classifying stars:

1.  Size

2.  Temperature

3.  Brightness

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Blue - Hottest (20,000-50,000*C)

White - (10,000*C)

Yellow -  (6,000*C)

Red-orange - (4,000-5,000*C)

Red - (3000*C)

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Brightness of stars:

Apparent Magnitude:  Brightness as seen from earth

Absolute Magnitude:  Brightness of a star from a standard distance

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SUPERNOVAS

The Solar Nebular Disk Model theory (SNDM): The theory is that gravity caused the nebula to collapse and eventually started spinning. The accelerating rotation combined with gravity formed a disk. The disk's center heats up, creating our sun and the solar system. The planets are then formed by accumulating matter from rings in the disk.

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1. Nebula begins to rotate
2. The speed of the spin increases and matter collapses
3. The gravitational collapse is much more efficient along the axis of the disk

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Evidence:

• All the planets orbit in the same direction around the Sun and on the same plane
• All the inner planets are dense, rocky, low in mass, and high in density
• While the outer planets are less dense, gaseous, high in mass, and low in density

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Early stages of a planet:

• Planetesimals
• Protoplanets

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Planetesimals: Condensed material from the early stages of formation of the solar system. These small objects collide and merge to form a protoplanet.

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Galaxy first planet: Jupiter

Many icy planetesimals merged, attracting more of the surrounding dust and gas. Other gas planets like Saturn would follow but would be smaller due to Jupiter having already collected more of the available material

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In conclusion: Solar Nebular Disk Theory is the predominant theory for the origin of the Solar System. The gas and dust that formed our sun and the planets were rotating around the same axis. Gravity pulled together the matter and formed planetesimals and eventually planets

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Kepler’s First Law

• The orbits of the planets are not a circle
• The planets’ orbits is actually an ellipse (oval) and the Sun is located at a focus point
• Focus points are not the center of the orbit (they're off to the side)

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Kepler's second law:

• The planet moves faster when close to the Sun and slower when away from the Sun

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In conclusion:

• Kepler’s first law states that the orbits are actually ellipses
• Kepler’s second law states that the planets move faster when close to the Sun. (Earth orbits the sun the fastest during January).

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PLANET SIZES COMPARISON

• Outer planets have more mass than the inner planets due to their large size
• How many Earths could fit in Jupiter?: 1,300
• Inner planets are smaller but denser

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ASTEROIDS:

• Small celestial bodies are primarily made out of the rock and dust that orbits the Sun
• The majority of asteroids are found in the asteroid belt between Mars and Jupiter
• The mass of all asteroids is less than the mass of our moon
• We have successfully landed spacecraft on asteroids
• Asteroids are capable of having smaller moons that orbit them
• Some asteroids have evidence of running water; however, they can’t sustain life

Comets:

• They’re small celestial body that orbits the Sun similar to asteroids
• The main difference between asteroids and comets is the composition
• Comets are mainly made of gas and ice, nickname “Dirty Snowballs”

Comets orbit:

• Comet’s orbits are also elliptical; Even more elongated than planets

• Comets fly into the solar system from a region outside pluto called the Oort Cloud

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Anatomy of a comet:

Nucleus: the nucleus of a comet is composed of ice and rocky material. The nucleus of most comets ranges from about 10 to 100 km in diameter

Coma: the cloud of gasses that forms around the nucleus as the coma is heated is known as the coma.

Dust Tail: A comet's dust tail is composed of gasses and tiny dust particles blown away from the nucleus as the comet is heated.

Ion Tail: The ion tail is a stream of ionized gasses that are blown directly away from the Sun due to the comet’s contact with the solar wind.

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STELLAR CLASSIFICATION & PLANET DETECTION: \n Within 12.5 light years, there are 33 stars. Most of them are Red dwarfs.The ultimate goal is to find Earth-like planets, if they exist, and to search for evidence of life.

Exoplanet detection methods:

Indirect:

• Radial velocity (Doppler method)
• Transits
• Gravitational microlensing
• Pulsar planets
• Astrometric

Direct

• Optical imaging
• Infrared interferometry

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Exoplanet types:

• Neptune
• Gas giants
• Super Earth
• Terrestrial
• More than 5000 Exoplanet have been confirmed by NASA

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Gravitational microlensing:

• Planets can also be detected by gravitational microlensing. This method takes advantage of the fact that, according to general relativity, light rays are bent by a gravitational field. Or equivalently, space-time is distorted and light travels along straight paths in the distorted reference frame)
• When the lensing star passes in front of the source star, the light from the source star is amplified by a factor of as much as 10-20.
• The typical duration of a microlensing event is minutes to hours
• If the lensing star has planets, then the light curve can be distorted (i.e., you get spikes)

The planets must be near the Einstein ring radius to be detected. Typically, the ring radius is outside of the habitable zone, so this technique is not that useful for finding habitable planets

• The majority of all detected planets have masses below that of Saturn, though the survey sensitivity is much lower for those planets. Low-mass planets are thus found to be much more common than giant planets.

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FORMATION OF ATMOSPHERE:

• The scale of time periods: Epoch<Period<Era<Eon

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Geological abbreviations for time:

• Ga - Billion years ago
• Ma - Million years ago
• Ka - Thousand years ago

Volcanic Outgassing: Volcanoes emit the following gasses:

• Water Vapor
• Carbon dioxide
• Trace amounts of nitrogen

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RELATIVE DATING

Relative age: Relative means determining if something is younger than or older than something else. Relative age does not tell how old something is; all we know is the sequence of events.  For example, a volcano is younger than the rocks that occur underneath it.

Radioactive dating: Allows us to figure out how old something is exactly, based on the fact that all things on Earth contain certain materials that change over time. Radiometric dating uses the half-life of atoms to figure out the age of the rock layers the atoms are in.

Absolute dating: Finding the exact age of an object.

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Fossil records:

• Fossils permeate layers of sedimentary rock
• The fossil record keeps track of how life progressed
• By using the law of superposition, the progression of life can be determined
• Relative ages -  Principles of Stratigraphy
• Correlations - Fossils, key beds, lithologic similarity
• Numeric ages - Radiometric dating.

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Principle of Uniformitarianism: Present = past

• James Hutton 1726-1797
• He examined rocks in Scotland and noted that features like mud cracks, ripple marks, graded bedding, etc, were the same features that could be seen forming in modern environments.  He concluded that the process that is currently operating on the Earth must be the same processes that operated in the past. This principle is often stated as "the present is the key to the past".

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Principle of  Superposition

• A principle within a sequence of layers of sedimentary rock, the oldest layer is at the base and the layers are progressively younger with ascending order in the sequence.
• Old = bottom layers
• New = top layers

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Principle of Original Horizontality

• Sedimentary strata are deposited in layers that are horizontal or nearly horizontal, parallel to or nearly parallel to the Earth's surface.

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Principle of Original Continuity

• If layers are deposited horizontally over the sea floor, then they would be expected to be laterally continuous over some distance. Thus, if the strata are later uplifted and then cut by a canyon, we know that the same strata would be expected to occur on both sides of the canyon.

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Principle of Cross-cutting Relations

• Younger features truncate (cut across) older features. Faults, dikes, erosion, etc., must be younger than the material that is faulted, intruded, or eroded.

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Principle of Inclusions

• If we find a rock fragment enclosed within another rock, we say the fragment is an inclusion. If the enclosing rock is an igneous rock, the inclusions are called xenoliths.

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Fossil index:

• It was soon recognized that some fossils of once-living organisms only occurred in very old rocks and others only occurred in younger rocks. Furthermore, some fossils were only found within a limited range of strata and these fossils, because they were so characteristic of relative age, were termed index fossils.

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ORIGIN OF LIFE

Spontaneous Generation- The hypothesis that life arises regularly from non-living things.

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Disprove Spontaneous Generation:

• In 1668 Italian physician and poet, Francesco Redi, created the first experiment to disprove spontaneous generation. He took three jars and placed cut meat in each one of them. One uncovered, one covered with a net, and the last one completely sealed. —------------ In the end, the only jar that was untouched by maggots (or flies), that was empty, was the sealed jar. He demonstrated that the presence of maggots in meat does not result from spontaneous generation but rather the eggs laid by flies.

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• In 1859 French scientist Louis Pasteur provided evidence that Microorganisms do not arise from meat broth. He placed meat broth in a flask with a long curved neck, which was boiled of all microorganisms, and left it alone for an entire year. —--------------- When Pasteur returned, he found no microorganisms in the broth. They had only appeared once he removed the curved neck, exposing the broth to dust and other particles.

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Theories explaining the formation of life:

The Miller/Urey Experiment (1953): Miller and Urey simulated the conditions of Earth’s early atmosphere and oceans, adding energy to simulate the lightning that was believed to be commonplace. After one week, 10-15% of the carbon had turned into organic compounds, and 2% of the carbon had created amino acids, the building blocks of proteins. This was the first evidence that organic molecules needed for life could be formed from inorganic components.

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The Oparin-Haldane hypothesis:

• That life on Earth could have arisen step-by-step from non-living matter through a process of “gradual chemical evolution.” They thought that early Earth had a reducing atmosphere.
• Under these conditions, they suggested that simple inorganic molecules could have reacted (with energy from lightning or the sun) to form building blocks like amino acids and nucleotides. The building blocks could have combined in further reactions, forming larger, more complex molecules like proteins and nucleic acids.

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Molecules from Space

• Many of the compounds produced by the Miller/Urey experiment are known to exist in space. If these compounds can survive the harshness of space, perhaps they were present when earth initially formed. Organic molecules could have also been brought to earth by space debris.

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How did chloroplasts originate inside the early stromatolites?: Endosymbiosis

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How long ago did oxygen enter our atmosphere?: 2.3 bya

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• The earliest evidence of life on Earth comes from fossils discovered in Western Australia that date back to about 5 billion years ago. These fossils are of structures known as stromatolites.

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Principles to determine the relative dating:

• Relative dating is to estimate the age of something through comparison/sequence without a specific number. It doesn’t tell how old something is since all we know is the sequence of events.
• Numeric age means that we can more precisely assign a number (in years, minutes, seconds, or some other units of time) to the amount of time that has passed.
• Correlation: To correlate rock units, something distinctive must be present in each. This can include an index fossil, a key bed, or lithologic similarity.

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Early Earth was pummeled by asteroids and other celestial objects. Temperatures were pretty high (with water taking the form of a gas, not a liquid). The first life might have emerged during a break in the asteroid bombardment, between 4.4-4.0 billion years ago, when it was cool enough for water to condense into oceans. A second bombardment happened about 3.9 billion years ago. It’s likely after this event that Earth became capable of supporting sustained life.

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CONVECTION

Convection currents are the upward movement of warm air and the downward movement of cool air.

Heat:

• The energy transferred from one object to another because of a difference in the objects’ temperature. As water's temperature increases due to a heat source, it becomes less dense and rises. Away from the heat source, it cools and becomes more dense and sinks.

Temperature:

• measure of the average kinetic energy of the individual atoms or molecules in a substance.

Sea breeze:

• During a hot day, the land is warmer than the sea. Air above the land is heated and rises up; it is then replaced by cooler air from the sea. The wind blows from the ocean towards land.

Land breeze:

• During the night, the sea is warmer than the land because the land loses its heat much faster than the sea. The air above the sea is warmer than that above the land so it rises up to be replaced by that air above the land. The wind blows from the land to the water.
• Convection– heat transfer by the movement (circulation) in fluids.

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Half life

Radioactive substance decay is called half life. The original atom (isotope) is called the “parent.” The new form of the atom is called the “daughter.” Half of the parent atoms turn into the daughter atoms once the object has reached a certain age. A half-life is the time needed for one-half of the parent atoms to turn into daughter atoms. Radiometric dating uses the half-life of atoms to figure out the age of the rock layers the atoms are in.

• 1-5 half life: 50, 25, 12.5, 6.25, 3.125

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Rocks

Three classification is: sedimentary, igneous, and metamorphic

Igneous rocks began as magma. They form from the solidification of magma, so extreme heat, pressure, and composition.

• Intrusive rocks are when magma pushes into surrounding rock below the Earth’s surface
• Extrusive Rocks forms when magma erupts onto the Earth’s surface and cools down quickly

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Sedimentary Rocks are created at/near the Earth’s surface. They’re formed through a series of processes called erosion, deposition, compaction, and cementation. Sedimentary rocks have lots of layers through stratification (the process in which sedimentary rocks are arranged in layers).

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Metamorphic rocks are formed by intense heat and pressure, Either deep in Earth’s crust or at plate boundaries where tectonic plates collide.

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Foliated – contain aligned grains of flat minerals

Non-Foliated – mineral grains are not arranged in plains or bands

Law of superposition – The older rocks are on the bottom and the younger rocks are on top