Astronomy Notes Astronomy 138
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This 10 page Bundle was uploaded by Tara Heuple on Sunday October 11, 2015. The Bundle belongs to Astronomy 138 at Washington State University taught by Nicholas Cerruti in Summer 2015. Since its upload, it has received 208 views. For similar materials see Planets and The Solar System in Science at Washington State University.
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Date Created: 10/11/15
Tuesday August 25 2015 Astronomy 138 Position Celestial Sphere is where the stars are The stars lie at different distances but they appear to be on the sphereThe top pole is the north celestial pole and the bottom pole is the south celestial pole The ecliptic is the path is the celestial sphere that the sun follows as it appears throughout the celestial sphere It takes one year to go around The angle between the ecliptic is 235 degrees The zenith is the point directly overhead The meridian is an imaginary half circle that stretches from the horizon due south through the zenith to the horizon due north Anti Meridian is AM which is before the sun passes and Post Meridian is PM which is after the sun passes Motion The Earth rotates from west to east The celestial sphere appears to rotate from east to west and the Earth rotates from the west to the east If you are standing on the Earth then your horizon is all around you The circumpolar star is one that always stays visible and the star rises and sets There are two ways to define a day There is a solar day which is the average time that it takes the sun to make one circuit throughout the sky A solar day is a normal 24 hour day A sidereal day is the time that it takes the stars to make one circuit through the sky A sidereal day is 23 hours and 56 minutes and makes a 360 degree circle Planets The word planet comes from the greek word for wandering star The classical planets are named after the Greek Gods From them there is the Sun Moon Mercury Venus Mars Jupiter and Saturn The Geocentric Model says that everything goes around the Earth Mercury and Venus always stay near the sun Retrograde motion is a period where a planet moves westward backward relative to the stars The sun and the moon do not experience retrograde motion The Ptolemaic Model is when the planets move in epicycles In this Earth is slightly off center At the bottom of this cycle it looks like retrograde and at the top it looks like prograde Tuesday August 25 2015 The Copernican Model is when the sun is near the center of the universe The planets move in perfect circles including epicycles The moon revolves around the Earth and and the order of the planets are Mercury Venus Earth Mars Jupiter and Saturn The Earth has three motions which are the daily motion the annual revolution and the annual tilting of its axis The retrograde motion has the sun in the riddles and then the planets are revolving around it Retrograde motion is an e like swirl to count and label the stars Tycho Brahe 15461601 is known for his accurate observations of the planets and the stars He did this all without a telescope Kepler s Law was established in 1610 and 1618 The first law was that the planets followed elliptical orbits with the sun at one focus of the ellipse The closest point to the sun is called the perihelion and the furthest point from the sun is called the aphelion The eccentricity is how much the ellipse deviates from a perfect circle If there is only one point there is zero eccentricity if there are two points that are relatively close then they are moderate eccentric and if there are two points that are spread out then they are highly eccentric The semi major axis is the average of the planets perihelion and aphelion distances His second law is stated that as a planet moves in its orbit it sweeps out an equal amount of area in an equal amount of time Planets travel faster around when they are at perihelion The third law tells us how more distance planets orbit around the sun at slower average speeds obeying the precise mathematical relation where the planet s period in years squared is equal to the planet s semi major axis in astronomical units Au stands for the Earth s average distance from the sun Galileo Galilei 15641642 was one of the first to use a telescope and observe stars and planets with it He noticed that the sun had spots and he looked at the moon and found that it was similar to the Earth and noticed mountains and craters on the moon He noticed the phases of Venus and all the phases present He discovered the moons of Jupiter and discovered the ring of Saturn He also discovered the resolution of the Milky Way into the countless number of stars The sunspots and the moon features were not perfect and the orbits of those objects aren39t perfect circles either The phases of Venus are in a ptolemaic model Tuesday August 25 2015 Jupiter has four large moons surrounded by it Not everything orbits around the Earth The Milky Way has more numerous stars and is more distant than people previously thought Tuesday September 1 2015 Astronomy 138 Discovery of the Planets In 1655 Titan was orbiting Saturn and now they are called moons In 1781 Uranus was orbiting the Sun past Saturn and was the 7th planet in the solar system From 1801 to 1807 Ceres Pallas Juno and Vesta was orbiting the Sun between Mars and Jupiter They are now called asteroids In 1846 Neptune was orbiting the Sun past Uranus which was the 8th planet In 1930 Pluto was orbiting the Sun past Neptune which is now called a dwarf planet In 1992 there were many transNeptunian objects A planet is a celestial body that is in orbit around the sun it has a nearly round shape and it has cleared the neighborhood around its orbit The 8 planets in order from the Sun are Mercury Venus Earth Mars Jupiter Saturn Uranus and Neptune A dwarf planet satisfies the first two criteria of a planet Current dwarf planets are Pluto Ceres Eris Makemake and Haumea All other objects orbiting the sun are called small solar system bodies and those include asteroids transNeptunian objects and comets Seasons The Earth is tilted at 235 degrees with respect to it39s orbital plane This s the same degree between the ecliptic and celestial equation During the orbit summer is at the top winter is on the right fall is on the bottom and summer is on the left Lunar Phases The top moon is in the first quarter the left one is in full moon the bottom one is in the third quarter and the right moon is in new moon phase The moon orbits the Earth every 27 and a third days and the time between the full moon is 29 and a half days Tuesday September 1 2015 Approximate Rise and Fall Set Times New Moon When the moon is at it s highest point zenith is around noon lt rises around 6 am and sets around 6pm Full Moon When the moon is at zenith it is midnight lt rises around 6pm and sets around 6am First Quarter When the moon is at zenith it is 6pm lt rises around noon and sets around midnight Third Quarter When the moon is at zenith it is Sam lt rises around midnight and sets around noon A waxing crescent is a new moon to a full moon A waning crescent is a full moon to a new moon The phase of the moon must be a full lunar eclipse and a new solar eclipse The new or full moon must occur during a node of the moon s orbit The tilt is about 5 degrees The node is the point where the moon crosses the plane or the ecliptic the line between the Earth and the sun Shadows With the different kinds of shadows you get different eclipses A total lunar eclipse is when the moon passes entirely through the umbra A partial lunar eclipse is when it doesn39t pass all the way through the umbra A penumbral lunar eclipse is when the moon passes only through the penumbra A partial solar eclipse is when part of the sun is blocked out 7000 km in diameter A total solar eclipse is 270 km in diameter An annular eclipse is when you see a ring around the sun Tuesday September 8 2015 Astronomy 138 General Features of the Solar System Patterns of motion Planetary orbits are nearly circular and lie nearly in the same plane The planets orbit the sun in the same direction Most planets rotate in the same direction in which they orbit with small axis tilts Most of the solar system s large moons exhibit similar properties Existence of two types of planets The terrestrial Earthlike planets are Mercury Venus Earth and Mars The jovian Jupiterlike planets are Jupiter Saturn Uranus and Neptune Terrestrial planets have a small size and mass have a high density and are made out of rocks and metals They also have a solid surface have few or no moons have no rings are the first four planets in the solar system and have warmer surfaces Jovian planets have a larger size and mass have a lower density and are made mostly of hydrogen helium and hydrogen compounds They also do not have solid surfaces they have rings are farther from the sun and are cooler temperatures Asteroids and Comets They outnumber the planets and their moons Asteroids are rocky and the majority of them orbit the sun between Mars and Jupiter Comets are icy and the majority of them orbit the sun and beyond Neptune Exceptions Uranus has a large axis tit Venus rotates backwards Formation of the Solar System 14 billion years ago there was an event called the Big Bang that occurred Only hydrogen helium and small amounts of lithium are formed 100 years later the stars formed Stars are large nuclear reactors that produce heavy elements When stars die they release matter into space Our solar system was formed 46 billion years ago Nebular Theory The interstellar cloud contained 98 of hydrogen and helium The heating is from the gravitational potential energy that turns into thermal energy Tuesday September 8 2015 The spinning is the conservation of angular momentum lt spins faster as the clouds coHapse Flattening is when the particles collide and they move orderly in direction and speed Planet Formation The temperature decreases The materials in the solar nebula are hydrogen and helium and they do not condense very easily Hydrogen compounds are 14 and examples of this are water methane and ammonia Within frost lines terrestrial planets are formed and outside the lines are were jovian planets are formed Terrestrial Planets Microscopic solid particles condense Particles collide and stick together through static electricity Planetesimals pieces of planets form attracting more particles by gravity A few planetesimals grow larger by colliding and others will shatter Only the largest planetesimals will survive Jovian Planets These are large icy planetesimals that form Planetesimals grow to many times of the mass of the Earth Gravity increases attracting hydrogen and helium Heating spinning and flattening the local dish causes moons to form Asteroids and Comets are Leftovers They are planetesimals that are clearing the nebula Solar winds are charged particles from the sun and they sweep out the hydrogen and helium Meteorites Tuesday September 8 2015 A meteoroid is a small sand to bouldersize small solar system body A meteor is a flash of light caused by a meteoroid entering a planet s atmosphere A meteorite is a meteoroid is something that impacts the planet s surface Types of Meteorites Primitive meteorites are simple mixtures of rock and metal They have leftover planetesimals and are 46 billion years old Processes differentiated meteorites have experienced a major chemical change These are pieces of shattered planetesimals or of larger bodies and are less than 46 billion years old Radioactive Dating Radioactive decay is an element that changes into another element by emitting some type of radiation The rate of decay is measures in half lives Numbers for homework should add to 16 Tuesday September 15 2015 Astronomy 138 Eanh The interior structure included the mantle which is 3000 km thick the core which is 3400 km radius and the crust which is 1570km thick The core is the highest density which is made up of mostly nickel and iron The mantel is moderately dense and is mostly composed of minerals that are carbon silicon and oxygen The crust is the lowest dense and contains basalt and granite The lithosphere is the coolest and most rigid layer of rocks near the planets surfaces and is 15 to 00 km thick Differentiation is the process which gravity separates materials by its density Internal heat is all the terrestrial planets that once had enough heat inside for their interiors to melt The causes are extra terrestrial impacts gravitational contraction and the decay of radioactive elements This is over half of the total heat flux which is 44 trillion watts The mantel convection is when hot rocks rise and cold rocks sink The larger planets are more massive and they retain heat much longer than smaller ones Venus has internal heat similar to Earth Mars is cool and has some internal heat Mercury and the moon are cold Magnetic Field The Earth s core is broken up into two pieces The inner core and the outer core The inner core is a solid and is warmer and the outer core is a liquid and is colder A convection current and the Earth s rotation produce the magnetic field A magnetosphere has solar winds and they are charged particles There are a few particles that are channeled towards the poles They are deflected by the magnetic field Earth s Surfaces Tuesday September 15 2015 The processes which shape the Earth s surface are impact cratering volcanism tectonics and erosion Impact cratering is 150000 miles per hour and the place of impact is ten times as wide as the asteroid which is 1020 as deep as it is wide The Earth and the moon should have the same number of impacts ad there are less craters on the Earth The Earth is geologically active and the craters are erased The age of the planetary surface can be estimated Volcanism has molten rock in the magma chamber and lava and outgassing comes out of the top The products of outgassing is water vapor that is rained down from oceans carbon dioxide nitrogen which is 78 of the atmosphere and sulfur gasses Tectonics has expansion and compression of the Earth s crust and then there is the mantle and there are convection currents The Earth s lithosphere is broken into plates This is how the Hawaiian Islands were formed Erosion is both constructive and destructive
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