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Download 21 Formation of the Universe
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Formation of the Universe Nebula All the ingredients for building planets, moons, and stars are found in the vast, seemingly empty regions of space between the stars. Clouds in space are called Nebulas – mixture of gases (mainly hydrogen and helium) and dust (elements such as carbon and iron). Gravity pulls matter together – nebulas are less dense than air . Therefore the gravitational pull is very weak. Nebulae The relationship between temperature and pressure keep the nebula from collapsing. Temperature is the measure of average kinetic energy (energy in motion) of the particles in an object. Little energy = slow movement and low temperature High energy = fast movement and high temperature. Pressure = when the moving particles collide they push away from one another How a Solar System Forms Globules – compressed regions of a nebula Solar Nebula – the nebula that formed our solar system. (These collapse) Planetesimals – small planets Outer planets – planetesimals that formed near the outer part of the solar disk where the hydrogen and helium were located. (gas giants) Inner planets – planetesimals that formed closer to the nebula’s center (too hot for gases to remain ) mostly rocky material. Nuclear Fusion The process where the nuclei of two or more small atoms combine (fuse) to form a larger nucleus – releases a lot of energy. Sun = 4 hydrogen nuclei fuse together to form one nucleus of Helium. Radiative Zone – dense region of the Sun through which energy from the core passes Convective Zone – Region of the Sun where gases circulate and carry energy to the photosphere Photosphere – The visible surface of the Sun. Solar Activity Sunspots – cooler, dark spots of the photosphere of the sun. - Cycle about every 11 years. Solar Flares – regions of extremely high temperature and brightness that develop on the sun’s surface. Sunspots Solar Flares The Earth takes Shape Made mostly of rock, ¾ of the planet is covered with water. Surrounded by protective layer (atmosphere) made mostly of nitrogen and oxygen (and small amounts of other gases). Formed as a small planetesimals collided and combined. Gravity – holds us together and made our shape more round. Causes of Heat: Planetesimals colliding with Earth generated heat. Radioactive material heated the Earth All of this created an enormous amount of energy.. Effects of heat: Volcanoes, earthquakes, hot springs Created the layers of the Earth. Earth’s Layers The core of the Earth is like a ball of very hot metals. The outer core is liquid. The outer core is made up of iron and is very dense. 1.) Crust = thin and solid outermost layer of the Earth (above the Mantle) 2.) Mantle = The layer of rock between the Earth’s crust and core 3.) Core = The central part of the Earth below the mantle Layers of the EARTH CRUST 5 to 25 miles thick and up to 1,600 F MANTLE 1,800 miles thick and up to 8,000 F INNER CORE 800 miles thick and up to 13,000 F OUTER CORE 1,400 miles thick and up to 11,000 F Earth’s Atmosphere 78% Nitrogen 21% Oxygen 1% Argon -0.03 % Carbon Dioxide Misc. other gases. Early Atmosphere Early Atmosphere was a mixture of gases that were released as the Earth cooled. Scientist think that Earth’s early atmosphere was a steamy mixture of carbon dioxide and water vapor. (The molten rock released these) Volcanoes contribution Volcanoes probably formed from volcanic gases. They released chlorine, nitrogen, and sulfur as well as the carbon dioxide and water vapor. (Some of this water vapor may have condensed to form the Earth’s first oceans.) Comets crashed to Earth creating craters, also contributed carbon, hydrogen, oxygen and nitrogen to the Earth. Ultraviolet Radiation and Life Scientist think UV radiation helped produce the conditions necessary for life. It has a lot of energy and can break apart molecules in the air. With no Ozone to protect the early Earth. Molecules in the air and at the Earth’s surface broke up and ended up in the water. These chemicals may have combined to form complex molecules that made life possible. Then organisms that produced food by photosynthesis appeared and with this process oxygen was released. This increased over time and formed our ozone layer. Oceans and Continents Once the Earth cooled enough rain fell and remained on the surface. By about 4 billion years ago a global ocean covered the planet. Rocks on the Earth have melted and cooled many times – each time they melted the heavier elements sank and the lighter ones rose to the surface. After time, some of the rocks were light enough to pile on the surface. Voila – Continents. Planetary Motion Earth spins on its axis – the spin of a body on its axis is ROTATION. The ORBIT is the path that a body follows as it travels around another body in space. One complete orbit is a REVOLUTION. Therefore the Earth rotates on its axis and revolves around the Sun in an orbit. Kepler’s 3 Laws of Motion 1.) Planets orbit the Sun in an Elongated circle called an ellipse. An Ellipse’s maximum length is the MAJOR AXIS Half the distance is the SEMIMAJOR AXIS The semimajor axis is used to describe the size of the ellipse. 2.) Planets move faster closer to the Sun and slower when they are far away. 3.) Planets further away from the Sun take longer to orbit the Sun. Law of Universal Gravitation Newton’s law of Universal Gravitation states that the force of gravity depends on the product of the masses of the objects divided by the square of the distance between the objects. so if the objects are moved twice as far apart = 2² if they are moved 10 times as far apart = 10² Inertia = an object’s resistance in speed or direction until the outside force acts on the object. Chapter 21 Calculations Distances are measured in Astronomical Units One AU (astronomical unit) = distance from the Earth to the Sun. The Speed of light = 300,000 km per second Light minute = the distance light travels in one minute (18,000,000 km) How many AU = 8.3 light minutes? One Distances can be measured in Light minutes as well as light hours. Telescopes Up until the 17th century only 8 bodies were known.. Earth, Mercury, Venus, Mars, Jupiter, Saturn, the Sun and the Moon. When the telescope – 9 more large bodies were known by the end of the 17th century. By the end of the 18th century Uranus, its two moons and two more of Saturn’s moons. In the 19th century Neptune and the moons of other planets discovered. 20th century – Pluto and other bodies found Inner verses Outer 4 closest planets to the 4 farthest planets from Sun Denser and Rockier – known as terrestrial planets Spaced closely together the Sun Larger and composed mainly of gas. “Gas Giants” Terrestrial planet = one of 4 highly dense planets near the Sun Section Review 1.) What is an Astronomical Unit? The average distance from Earth to the Sun 2.) When was Uranus discovered? 18th Century 3.) What invention helped early scientist discover more bodies in our solar system? Telescope 4.) How are the inner planets different from the outer planets? Inner planets are dense and rocky – the outer ones are large and made mainly of gas Rotations Prograde Rotation = The counterclockwise spin of a planet or moon as seen from above the planet’s north pole. (same as Sun’s rotation). Retrograde Rotation = The clockwise spin of a planet or moon as seen from above the planet’s north pole. How Old If I lived on Mercury I would be 178 years old and Mrs. Lewis would be 149. If you are 10 you would be 42 If you are 11 you would be 46 If you are 12 you would be 50 Because on Mercury 1 year = 88 days. Rotation verses Revolution Rotation Revolution Mercury = 58days 19hours 88 days Venus = 243days 16hours (R) 224days 17 hours Earth = 23hours 56 min 365days 6hours Mars = 24hours 40 min 1year 322 days On Venus a day is longer (243 days) than a year (224) Venus Venus is only slightly smaller than Earth. Its atmosphere is slightly less dense, and slightly less massive. Because it has a retrograde rotation, the Sun rises in the west and sets in the east. It has volcanoes on the surface like Earth Its surface temperature is 464⁰ c – this is due to its greenhouse effect. Greenhouse effect is where the carbon dioxide traps all the thermal energy from sunlight. Why is Earth so Special? 1.) Earth formed at just the right distance from the Sun. Therefore it is warm enough to keep most of its water from freezing but cool enough (unlike Venus) to keep its water from boiling away. (liquid water is essential for chemical processes that living things need). What is the Earth Science Enterprise? NASA’s program that uses satellites to study Earth’s atmosphere, land, oceans, life, and ice. Mars Mars has a thinner atmosphere and of the 4 inner planets it is the farthest away from the Sun. Colder – and the air is so thin it is like our atmosphere at 30,000km This makes the pressure so thin that liquid water boils quickly away. The only water present is in the form of ice. – (Evidence shows that liquid water existed in Mars’ past). Scientist believe that the water now exists as polar ice caps and as ice beneath the surface. Section Two Review What is a terrestrial planet? Define Prograde Rotation Define Retrograde Rotation. What is the difference between a planet’s period of rotation and period of revolution? Why is Venus’ surface temperature higher than other planets? A planet that has a solid rocky surface A counterclockwise rotation of a planet or moon. A clockwise rotation of a planet or moon Period of rotation = time a planet takes to rotate on its axis. Period of revolution = time a planet takes to revolve around the Sun Because of its greenhouse effect The Outer Planets – Gas Giants Rotation Revolution Jupiter = 9 hours 54 minutes Jupiter = 11 years 313 days Saturn = 10 hours 42 minutes Saturn = 29 years 155 days Uranus = 17 hours 12 minutes Uranus = 83 years 273 days Neptune = 16 hours 6 minutes Neptune = 163 years 263 days Gas Giants are planets that have deep, massive atmospheres rather than hard and rocky surfaces like those of the inner planets. Jupiter Jupiter is the largest planet in our solar system Atmosphere is made of layered clouds of water, methane and ammonia. Gives off more energy than it receives from the Sun. Great Red Spot = a storm system over 400 years old and about 3 times the diameter of Earth Saturn Still forming (helium falls from the atmosphere and sinks to the core). Rings are made of icy particles ranging in size from a few cm to several meters wide. Atmosphere is made of methane, ammonia, and ethane. Gives off more energy than it receives from the Sun Uranus Neptune Atmosphere is mainly hydrogen Atmosphere is mainly hydrogen and methane Blue color comes because the elements (hydrogen and methane) absorb the red part of sunlight. Tilted – Uranus is tipped over on its side. Its axis of rotation is tilted almost 90⁰ and methane. Atmosphere has belts of clouds that are much more visible. Great Dark Spot like Jupiter’s Great Red Spot. Pluto Now classified a Dwarf Planet ½ the size of Mercury Made mainly of ice and rock. (scientist think that it is covered in frozen nitrogen) Atmosphere = thin and made of methane Moon (Charon) is half Pluto’s size. Pluto’s classification was questioned when Eris was discovered – Eris is larger than Pluto. Dwarf Planets = any object that orbits the sun, is round because of its own gravity, but has not cleared its orbital path. Classification A planet orbits a star Has enough mass to be rounded out by its own gravity. Not massive enough to cause thermonuclear fusion Has cleared its own field of debris. (planetesimals, etc) Moons (section 4) Satellites – a natural or artificial body that revolves around a planet. The surface of the moon tells us a lot. We know how old the moon is and can therefore count the number of craters to find the rate of cratering since the birth of our solar system. This information can be used to number the craters on other bodies and determine their age. How our moon formed When we collected moon rocks during Apollo 11, scientist found their composition to be similar to that of the Earth’s mantle. Scientist believe that while the Earth was forming a large Mars-sized object hit the Earth and a part of the mantle was blasted into orbit. Phase: The change in the sunlit area of one celestial body as seen from another celestial body. Phases of the Moon Waxing = the sunlit fraction that we can see is getting larger. Waning = the sunlit fraction is getting smaller. Half the moon is always lit by the sun just like half of the Earth is always lit. The moon’s period of rotation is the same as its period of revolution so we always see the same side of the moon. Eclipse = an event in which the shadow of one celestial body falls on another A solar Eclipse – the moon comes between Earth and the Sun – the shadow of the moon falls on part of the Earth A lunar eclipse – Earth comes between the Sun and the Moon – the shadow of the Earth falls on the Moon The Moons of Other Planets Mars has two moon – Phobos and Deimos (they are small, dark, and oddly shaped. Surface materials like some asteroids. All the Gas Giants have multiple moons. Jupiter has dozens of moons – The largest are Ganymede, Callisto, Io, and Europa. These were all discovered by Galileo in 1610. (Galilean satellites). Saturn also has dozens of moons – made mostly of frozen water. The largest is Titan. Jupiter Saturn Uranus, Neptune and Pluto’s moons Uranus has several moons – made of ice and rock. Miranda has smooth cratered plains but it also has regions with grooves and cliffs. Neptune – several known moons. Only one is large – Titon. It has a retrograde orbit. Pluto – has at least three moons. Charon, Hydra, Nix The largest is Charon. Section Summary A ______ is a body that revolves around a larger body (natural or artificial). Ganymede is a Galilean satellite ? Describe the current theory for the orgin of Earth’s moon. What causes the phases of the moon? What is the difference between a lunar and a solar eclipse? Satellite True A large body collided with Earth causing part of the Earth’s mantle to eject into orbit around the Earth The phases result from the moon’s changing position relative to Earth and the Sun. Lunar = Earth comes between the Sun and the Moon. Solar = the moon comes between Earth and the Sun Comets Comet – A small body of ice, rock, and cosmic dust loosely packed together. (dirty snowballs). Comets have tails when they come close to the Sun. The solar radiation heats the ice so the comet gives off gas and dust in the form of a tail. Sometimes it has two tails – an ion tail and a dust tail. The center is the nucleus. Orbits the Sun in a elliptical manner Many scientist think that comets come from the Oort cloud. – a spherical region that surrounds the solar system. They also exist in the Kuiper belt (outside the orbit of Neptune). Asteroids and Meteroids Asteroid = a small rocky object that orbits the sun. Asteroid belt = The region of the solar system that is between the orbits of Mars and Jupiter. Asteroids in the outermost region have dark reddish brown to black color. Asteroids in innermost region have light gray (stony or metallic composition). Meteoroids Meteoroid = a relatively small, rocky body that travels through space. Meteorite = a meteoroid that reaches the Earth’s surface without burning up completely. (Three types – stony, metallic, stony-iron) Meteor = a bright streak of light that results when a meteoroid burns up in Earth’s atmosphere. Meteor shows = large numbers of meteors. (Happen when Earth passes through the dusty debris that comets leave behind). Impacts Impacts happen when an object in space collides with another object. How often do large objects strike Earth? Large objects strike Earth every few thousands years The Torino scales is a system that allows scientist to rate the hazard level of an object moving toward Earth. It ranges from 0 – 10. Zero is a very small change and 10 a definite strike. The scale also has color codes – White = 0, Green = 1, Yellow = 2, 3, 4, Orange = 5, 6, 7 and Red = 8, 9, 10. Section Review Explain the difference in meteor and meteorite Why do a comet’s two tails point in different direction? How can cosmic impact affect life on Earth? Where is the asteroid belt located? What is the Torino scale? Meteor is streak of light because it has burned up in the atmosphere – meteorites reach the surface The ion tail is blown away from the Sun by the solar winds but the dust tail is not. It can change the global climate, destroy cities, etc. Between Mars and Jupiter. A system that enables scientist to rate the hazard level of an object moving toward Earth.
