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Transcript of 9Standard1
the collection of spectral lines emitted by a hot sample of an element.
Like a full spectrum except it is missing some spectral lines.
Observed when white light passes through a cool sample of an element.
The missing lines coincide exactly with that elements emission spectra. http://www.exploratorium.edu/origins/hubble/tools/doppler.html http://spacerip.com/mapping-the-history-of-space-time/ Light travels as a wave at a speed of approximately 3 x 10^5 km/s. Different colors of light have different wavelengths. As wavelength increases, energy decreases, so red light, with a wavelength around 750 nm has much less energy than blue light, with a wavelength around 450 nm. White light contains every color. It can be separated into individual colors by a prism. A prism is able to display the colors because it slows the speed of the light and causes it to bend. The light forms a spectrum because the amount each color is bent depends on its wavelength. Longer wavelengths will bend less than shorter wavelengths. Spectroscopy is the study of spectra (more than one spectrum). Each element has a unique set of spectral lines (dark or bright lines at specific wavelengths in a spectrum). Scientists can observe the spectrum from a star or galaxy to know what it is made of and if it is moving away from or toward us. If the emission spectrum of an element matches some of the spectral lines in the light emitted by a star scientists can conclude that the star contains that element. By analyzing many stars and galaxies for red shift or blue shift form the Doppler effect, scientists know that the universe is expanding because most stars and practically all galaxies are red shifted, which means these objects are moving away from us. This expansion is proportional to the distance from the galaxies to Earth. The farther away a galaxy is from us, the more it is red shifted and the faster it is traveling. The Electromagnetic Spectrum Viewing the Spectrum Spectroscopy Spectral Analysis in Astronomy Astronomy: The study of the universe beyond the earth. The Doppler Effect Big Bang theory: The universe was created with a massive explosion. Scientific Theory: an idea about the natural world that is subject to verification and refinement. Redshift: An apparent shift toward longer (redder) wavelengths of light emitted by an object, caused by the object moving away from the observer.
Blueshift: An apparent shift toward shorter (bluer) wavelengths of light emitted by an object, caused by the object moving toward the observer. Usually when the pattern of an element's spectra is found in starlight, the exact position of the spectral lines is "shifted" by the Doppler effect. This shift provides useful information about the motion of the star relative to earth. The Doppler Effect in Spectral Analysis The Expanding Universe Universe: All space, along with all matter and energy in space. Animation of Doppler Effect Why everything is red shifted Mapping the History of Space and Time If we were ever to find evidence that did not support the Big Bang theory, such as a blue shifted galaxy, how would that information affect the current theory? 1927- A Belgian priest, Georges Lamaître, was the first to develop a “big bang” theory. After studying red shifts of galaxies, he proposed that the universe began with an immense infusion of pure energy into space.
1929- Edwin Hubble discovered that the speed of a galaxy moving away from Earth was proportional to its distance.
1964- Arno Penzias and Robert Wilson discovered the cosmic background radiation.
1989- Cosmic Microwave Background Radiation, was measured by the Cosmic Background Explorer (COBE) satellite.
2001- The success of the COBE satellite prompted the development of a more sophisticated mission. The Wilkinson Microwave Anisotropy Probe (WMAP) satellite allowed scientists to take a closer look at the data from COBE – providing a more detailed map of the most ancient light in the universe and supplying additional evidence that is consistent with the Big Bang Theory. Birth of a Theory http://www.astro.ubc.ca/~scharein/a311/Sim.html The Nature of Science How has technology helped us to investigate ideas about the origins and nature of the universe? Standard I: Understand the scientific evidence that supports theories that explain how the universe and solar system developed. Earth Systems Objective 1: Describe the big bang theory and the evidence supporting it. Objective 2: Relate the structure and composition of the solar system to the processes that exist in the universe. http://www.classzone.com/books/earth_science/terc/content/visualizations/es2802/es2802page01.cfm?chapter_no=visualization http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::800::600::/sites/dl/free/0072482621/78778/Doppler_Nav.swf::Doppler%20Shift%20Interactive http://galileoandeinstein.physics.virginia.edu/more_stuff/flashlets/doppler.htm
Matter can not be created or destroyed. Law of Conservation of Matter So where did the matter that made the earth, the air we breathe, and our own bodies come from? http://www.spacetelescope.org/videos/heic0515a/ http://www.spacetelescope.org/videos/astro_ac/ An atom is the smallest unit of element that still retains the properties of that element.
Atoms are the building blocks of all matter. All matter is made of atoms and each element has its own specific atom.
The difference between atoms of different elements is the number of protons in the nucleus of an atom. The more protons in an atom, the heavier the element is. Atomic Review
Nuclear fusion is a reaction where the nuclei of atoms are fused together at high temperatures and energy is released. Hydrogen is the most abundant element in the universe, and is the most common atom in the fusion occurring in the sun. The hydrogen gas in the sun is a plasma, so the atoms are split into super-excited protons.
The process of nuclear fusion that produces most of the sun’s energy
consists of five steps: Nuclear Fusion
During each step of this reaction, energy is given off. This is what causes the sun to shine and provides us with all our energy from the sun.
This is also how heavier elements form in the stars. The more massive a star, the heavier the elements it can produce through fusion. However, there are some elements, called heavy elements, that can not be produced through the process of nuclear fusion and are only created in the colossal explosion of a supernova. 1. Two hydrogen protons collide and fuse.
2. One of the fused protons becomes a neutron.
3. Another proton combines with the proton-neutron pair,
producing a nucleus made up of two protons
and a neutron.
4. Two of these new nuclei collide and fuse.
5. The resulting cluster throws off two protons,
leaving a helium atom with two protons and two neutrons. The Sun For must of human history, people believed that the sun's energy came from fire. Not until the 20th century did we know what causes the sun's brilliance. The heat, light, and energy from the sun is produced in the process of fusion.
Because the sun is so bright, it can damage your eyes. Astronomers have to use special scientific instruments to study the sun. Spectroscopic analysis shows that most of the known elements are found in the sun. We also know that the sun is divided into three basic regions. The Core Sun Facts
*Diameter: 1,390,000 km (864,000 miles)
*Surface Temperature: 5,800 K (9980 F)
*Core Temperature: 15,600,000 K (28,079,540 F)
*Made up of 70% Hydrogen, 28% He, and <2% metals
*1,300,000 Earths could fit inside the sun!
* Every second, the sun converts 500 million tons of hydrogen into helium! The core of the sun is where fusion occurs. Temperatures and pressures within the core are so high that it is impossible for solids or liquids to exist. Gasses are changed into plasma as the electrons of atoms are ripped away by the extreme heat and pressure, leaving only rapidly moving ions. There are two inner zones, the radiative zone and the convective zone.
In the radiative zone surrounding the core, energy moves from atom to atom in electromagnetic waves.
In the convective zone, energy is transferred by convection. As energy is carried toward the sun’s surface, the gasses cool, sink, and become heated again. Heat is transferred to the sun’s surface as gasses continually rise and sink. The Inner Zones The Atmosphere Although the whole sun is made of gasses, the term atmosphere refers to the uppermost layer of solar gasses. The atmosphere is divided into three layers.
Photosphere: Most of the energy given off from the photosphere is visible light that is seen from the earth. This layer is considered the surface of the sun.
Chromosphere: This layer glows red and is hotter than the surface of the sun. Occasionally these gasses will shoot upward in a solar flare.
Corona: This is the outermost layer of the sun. It is a huge cloud that blends into space. It is heated by the sun’s magnetic field to about 2 ,000,000 C. The corona is only visible from earth during a solar eclipse. http://www.visionlearning.com/library/flash_viewer.php?oid=2747 Sun spots, Prominences, Solar flares, and Auroras http://www.nasa.gov/mission_pages/sunearth/news/News041612-M1.7flare.html http://mail.colonial.net/~hkaiter/life_cycle_of_a_star.htm Website w/ all sorts of good info and pictures. Coronal mass ejection The sun is a very active star. Not only is it fusing hundreds of tons of hydrogen every second at it's core, but the sun's surface is also constantly changing. solar flare: an eruption of electrically charged atomic particles solar wind: although the corona prevents most atomic particles from the surface of the sun from escaping, some of these ions stream out into space. The particles flow out to distant parts of the solar system. sun spots: sun spots are cooler than the surrounding gasses in the photosphere. They are caused by strong magnetic fields that slow convection, thereby lowering the temperature of the sun's surface. magnetic storms: occasionally, particles form a solar flare are flung out so forcefully that they escape into space, increasing the strength of the solar wind. When these gusts of particles hit the earth's atmosphere, it causes a disturbance in our magnetic field, called a magnetic storm. Severe storms interfere with radio communications, damage satellites, and pose radiation hazards. auroras: the most spectacular result of magnetic storms on earth is aurora. The sheets of light are produced when the electrically charged particles from the sun strike the gas molecules in the upper atmosphere. Life Cycle of a Star A star is a body of gasses that gives off a tremendous amount of radiant energy in the form of heat and light. The sun, like most stars we see in the sky, is a medium sized star. However, stars vary greatly in size (some are smaller than the earth, some can be over 1000X bigger than the sun!), color, composition, and brightness. Saggitarius Starfield
A star begins in a nebula, a cloud of gas and dust. A force, such as the explosion of a nearby star or a collision with another nebula, compresses the particles of the nebula, gravity begins pulling the particles together until a dense region of matter builds up within the cloud.
As this region becomes more dense, it begins spinning and flattens into a disk of matter with a central concentration called a protostar. As gravity pulls more and more matter toward the center of the protostar, pressure increases and temperature begins to rise.
Eventually, the gas becomes so hot that it becomes a plasma. When the temperature reaches about 10 million degrees C, fusion begins and a star is born. A Star is Born This is the longest stage in the life of a star. During this stage, energy is generated by fusing hydrogen atoms into helium atoms in the process of fusion. Fusion releases tremendous amounts of radiant energy.
A star does not expand in size during this stage because the force of gravity pulling matter inward and the force of energy from fusion balance each other out as long as there is a supply of hydrogen to fuse into helium. Main-Sequence Stage
Once almost all of the star’s hydrogen has been fused into helium, a star contracts from the force of gravity. This contraction increases the temperature in the core, causing the helium nuclei to fuse into carbon atoms. The energy released from hydrogen and helium fusion causes the star to expand to over 10 times (Giant) or at least 100 times (Supergiant) bigger than the sun.
The stages in the life of a star span over an enormous period of time. It is estimated that over the space of 5 billion years, the sun has converted only about 5% of its original hydrogen! Giant or Supergiant Stage
The final fate of a star depends on the size of the star. A medium-sized star becomes a white dwarf and either cools and dies or goes nova. A giant or supergiant will become a supernova, and then either become a neutron star or a black hole. Death of a Star
The end of helium fusion marks the end of the giant stage in the life cycle of a medium sized star and the star enters its final stages. The star expels its outer gasses, which are lit by the now exposed core as a planetary nebula. Gravity causes the remaining matter to collapse inward, creating a hot, dense core of matter, a white dwarf. White dwarfs will shine for billions of years before they cool completely. As they cool, they become fainter. When it no longer emits any energy, the star becomes a dead star, known as a black dwarf. White Dwarf Novas Some white dwarfs don’t just cool and die. During the process of cooling several massive explosions may occur releasing energy, gas and dust into space. When a white dwarf explodes, it is called a nova. A nova can burn up to 1 million times brighter than the sun before fading back to its normal brightness.
Stars that began as giants or supergiants end in a supernova. When these stars run out of helium fuel, gravitational force causes a contraction much greater than that of smaller-mass stars.
This collapse produces such high pressure and temperatures that nuclear fusion begins again, this time fusing heavier elements (carbon, magnesium, iron). Fusion continues until the core is almost entirely iron.
The iron absorbs huge amounts of energy and collapses, causing the outer part of the star to explode violently.
During a supernova, the energy released is approximately equal to the energy produced by an ordinary star over its entire lifetime! Supernovas Neutron Stars After the explosion, the core of a supernova may contract into an incredibly dense ball of neutrons called a neutron star.
A neutron star with more mass than the sun may be so compressed that its diameter is only 30 km (about 18.6 miles!). A spoonful of matter from a neutron star would weigh over 100 million tons on the earth.
Because so much mass is pulled into such a small area, a neutron star rotates extremely rapidly. Some neutron stars emit two beams of radiation and are called pulsars.
Some supernovas produce too much matter to become a neutron star. These stars contract with such immense force that they create a hole in space called a black hole. The gravity of a black hole is so great that not even light can escape it.
Since no light is given off, locating a black hole is difficult. Astronomers theorize that a black hole can be detected by its effect on a companion star. Matter from nearby stars is sucked into the black hole, disappearing forever from the universe. Just before matter is pulled in, X-rays are given off. Astronomers try to locate black holes by detecting these X-rays.
Astronomers have identified what they believe is a black hole in the constellation Cygnus. It is also speculated that massive or supermassive black holes may be at the cores of many galaxies. Black Holes http://www.nasa.gov/multimedia/videogallery/index.html?media_id=87330241 http://www.nasa.gov/multimedia/videogallery/index.html?media_id=142531021 Formation of our Solar System http://sciencenetlinks.com/interactives/messenger/psc/PlanetSize.html Planet size comparison http://www.educatedearth.net/video.php?id=5352 Bill Nye scale distance The universe began with the Big Bang. At this point, hydrogen and helium were scattered throughout the expanding universe. Over time, these elements were condensed into stars where heavier elements were created through the process of fusion and the explosion of supernovae. These heavy elements are the building blocks of our solar system. Our solar system began in a solar nebula composed of hydrogen and helium gasses, ice, and dust grains made of heavy elements. This nebula was at least 100 AU in diameter and had about 3x the mass of the sun. The solar system was shaped from this nebula by gravity, rotation, and heat. Gravity is the force of attraction between all matter in the universe. The larger the mass of an object, the larger its gravity.
A force acted on the solar nebula and set the particles in motion. Deep inside the nebula, gravitational attraction caused the particles to fall toward its center. As more matter accumulated, density and pressure increased, producing the protosun. Gravity AU= astronomical unit. This is a unit of measurement we use to measure huge distances in our solar system. 1AU=93,000,000 million miles. As density and pressure increased, collisions between atoms became more frequent. These collisions create heat, which eventually led to the temperatures required for the sun to begin fusion. Heat Rotation played a key role in the formation of the solar system. Rotation occurred because the formation of nebulae is turbulent (everything was swirling very slowly), so the nebula had angular momentum. Because of this angular momentum, planets began to form in the disk of matter surrounding the protosun. Rotation 3m The protosun’s temperature increased as it became denser. Heat began to radiate from the protosun, vaporizing ices and pushing light gasses away from the inner regions, leaving mostly heavy elements to form the inner planets, Mercury, Venus, Earth, and Mars.
Countless collisions of these heavy elements caused the particles to accumulate into planets over the course of 100 million years. Our solar system consists of the Sun, four terrestrial inner planets, four gaseous outer planets, moons, a handful of dwarf planets, the asteroid belt between Mars and Jupiter, and the Kuiper Belt and Oort Cloud beyond the orbit of Pluto. There are two forces acting upon the solar system that gives the solar system its structure. These are gravity and inertia.
Gravity is the tendency of all matter to be attracted together. Gravity pulls the earth toward the sun and puts us at our present distance.
Inertia is the tendency of a moving body to stay in motion. Inertia keeps the earth moving forward in its orbit around the sun. Our Solar System Today The process of how stars and solar systems are created and the forces that act upon solar systems are consistent throughout the universe. The forces that shaped our solar system have done the same in the past and are at work now, creating new worlds in this galaxy and in galaxies across the universe. http://video.pbs.org/video/1790621534/ 14m http://studyjams.scholastic.com/studyjams/jams/science/forces-and-motion/fgravity-and-inertia.htm Gravity and Inertia video (5m?) Cosmos: Star stuff, 8m Supernova http://2nd.watchknowlearn.org/Video.aspx?VideoID=18828&CategoryID=1789 http://www.wimp.com/starsize/ 3m http://www.wimp.com/galaxiesanimation/