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Unit 8 astronomy 09 10

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  • http://www.astronomycafe.net/qadir/q2811.html time to reach Mars
  • Visible Planet Orbits This diagram shows the relative size of the orbits of the seven planets visible to the naked eye. All the orbits are nearly circular (but slightly elliptical) and nearly in the same plane as Earth's orbit (called the ecliptic). The diagram is from a view out of the ecliptic plane and away from the perpendicular axis that goes through the Sun .
  • Outer Planet Orbits This shows the relative sizes and positions of the orbits of the planets farther from the Sun than Earth. All the planets have orbits that are ellipses with the Sun at one of the foci, and the ellipses are in different planes. However, in a perspective view of the orbits such as this one, only Pluto has a noticeably noncircular orbit that lies in a different plane from the other planets.

Unit 8 astronomy 09 10 Unit 8 astronomy 09 10 Presentation Transcript

  • Astronomy The Universe
  • Astronomy
    • The scientific study of matter in outer space, especially the positions, dimensions, distribution, motion, composition, energy, and evolution of celestial bodies and phenomena.
  •  
  • Big Bang Animation
  • What did the Big Bang sound like? Forget the big bang, tune in to the big hum THE big bang sounded more like a deep hum than a bang, according to an analysis of the radiation left over from the cataclysm. Physicist John Cramer of the University of Washington in Seattle has created audio files of the event which can be played on a PC. "The sound is rather like a large jet plane flying 100 feet above your house in the middle of the night," he says. Giant sound waves propagated through the blazing hot matter that filled the universe shortly after the big bang. These squeezed and stretched matter, heating the compressed regions and cooling the rarefied ones. Even though the universe has been expanding and cooling ever since, the sound waves have left their imprint as temperature variations on the afterglow of the big bang fireball, the so-called cosmic microwave background. Cramer was prompted to recreate the din- last heard13.7 billion years ago- by an11-year-old boy who wanted to know what the big bang sounded like for a school project. To produce the sound, Cramer took data from NASA's Wilkinson Microwave Anisotropy Probe. Launched in 2001, the probe has been measuring tiny differences in the temperature between different parts of the sky. From these variations, he could calculate the frequencies of the sound waves propagating through the universe during its first 760,000 years, when it was just 18 million light years across. At that time the sound waves were too low in frequency to be audible. To hear them, Cramer had to scale the frequencies 100,000 billion billion times. Nevertheless, the loudness and pitch of the sound waves reflect what happened in the early universe. During the 100-second recording ( http://www.npl.washington.edu/AV/BigBangSound_2.wav ), the frequencies fall because the sound waves get stretched as the universe expands. "It becomes more of a bass instrument," says Cramer. ### Author: Marcus Chown
  • What is the Big Bang Theory? The universe started as a single point. That point was extremely dense. It became unstable and exploded outward. Today the universe continues to expand.
  • The Universe
    • A massive explosion occurred, between 12 –15 billion years ago, and the universe has been expanding ever since
  •  
  •  
  • Evidence for the Big Bang The Doppler Effect & Cosmic Background Radiation
  • The Doppler Effect
  • Evidence for Expansion
    • The Doppler Effect is used as evidence that galaxies are moving away from us.
    • When light moves away, it’s wavelength is expanded (gets longer), meaning it becomes redder.
    • This is called the redshift.
  • Doppler Effect
    • All galaxies show redshift in their spectra, meaning they are moving away from us.
  • Evidence for the Big Bang light from distance galaxies all shift toward red
  • Shifts in the Electromagnetic Spectrum Red Shift = away Blue Shift = toward
  • Measuring Distance
    • Distances between celestial objects are extremely large.
    • Rather than miles, astronomers refer to a light-year as a standard unit of distance.
    • One light-year is the distance light travels in one year.
    • The speed of light is 186,000 mps (300,000 kps).
    • Thus, one light-year is about 6 trillion miles.
    • The nearest star to us (Proxima Centauri) is 4.2 light-years away.
  • Astronomical unit
    • Another unit of distance is the Astronomical Unit (AU).
    • One AU is the distance from the Earth to the Sun (93 million miles)
    • Distances to other objects are given in multiples of AU.
    • 384,000 km
    • 1 AU
    • 100 AU
    • 1 light year
    • 75,000 light years
    What is (approximately) the size of the solar system? 0 Remember: 1 AU = distance Sun – Earth = 150 million km 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
  • Galaxies
  • Galaxies
    • A galaxy is a collection of millions or billions of stars.
    • Galaxies can be spiral, elliptical, spherical or irregular in shape.
    • The Sun is part of the Milky Way galaxy, which is a spiral galaxy.
    • The Sun is located on one of the spiral arms, far from the galactic center.
  • Put these in order of size: galaxy solar system universe Largest Smallest universe galaxy solar system
  • Regents Question
    • Which sequence correctly lists the relative sizes from smallest to largest?
    • (1)our solar system, universe, Milky Way Galaxy
    • (2)our solar system, Milky Way Galaxy, universe
    • (3)Milky Way Galaxy, our solar system, universe
    • (4)Milky Way Galaxy, universe, our solar system
  • Regents Answer
    • (2)our solar system, Milky Way Galaxy, universe
  • Stars
    • A star is a huge, shining ball in space that produces a large amount of light and energy.
    • Stars come in many sizes.
    • About 75% are apart of groups that orbit each other.
    • They are grouped in large structures called galaxies . (Milky Way).
    • Stars have life-cycles like humans.
    • A stars color depends on surface temperature.
    Star
  • Stars
    • Stars are burning masses of gas.
    • Their energy is the result of nuclear fusion, in which Hydrogen atoms combine to form Helium atoms, releasing energy.
    • Electromagnetic energy is radiated by stars.
  • Star Characteristics
    • Stars vary in their size, mass, density, temperature and composition.
    • Luminosity – the actual brightness of a star
    • Luminosity depends only a star’s size and temperature
  • Composition
    • Stars are primarily made of Hydrogen and Helium
    • Many other elements are present in stars in small amounts
    • A star’s composition can be determined by spectral analysis.
  • How do stars generate their energy? Nuclear Fusion Hydrogen Hydrogen Helium
  • Spectral Analysis
    • Spectral analysis is the study of the electromagnetic spectrum emitted by a star, using a spectroscope.
    • Each element emits radiation is a specific set of wavelengths
  • Electromagnetic Spectrum
  • Color and Temperature
  • Betelgeuse is Rigel is What color are the stars in the constellation Orion? ESRTs p15 Red Blue
  • Orion
  • ESRTs p15 What are the main classifications of stars? Blue Supergiants Red Giants Main Sequence White Dwarfs Red Dwarfs
  • What type of star is our Sun classified as? ESRT p15 Main Sequence Circle where it is on the chart
  • The H-R Diagram
    • The Hertzsprung-Russell (H-R) Diagram is a graph of stars, comparing luminosity and temperature.
    • Stars are categorized according to these two properties
  • The H-R Diagram
    • Main Sequence – band into which most stars fall
      • High temperature, high luminosity
      • Low temperature, low luminosity
    • Red Giants and Supergiants – cooler, very luminous stars that are very large
    • White Dwarfs – hotter, low luminosity stars that are small
  •  
  • Shade the chart where all of the stars are hotter than our sun. Draw a line on the chart which separates those stars brighter than our sun and those less bright. ESRTs p15
  • The H-R Diagram
  • Regents Question
    • Which statement describes the general relationship between the temperature and the luminosity of main sequence stars?
    • (1) As temperature decreases, luminosity increases.
    • (2) As temperature decreases, luminosity remains the same.
    • (3) As temperature increases, luminosity increases.
    • (4) As temperature increases, luminosity remains the same.
  • Regents Answer
    • (2) As temperature increases, luminosity increases.
  • Regents Question
    • Compared to other groups of stars, the group that has relatively low luminosities and relatively low temperatures is the
    • (1)Red Dwarfs (3)Red Giants
    • (2)White Dwarfs (4)Blue Supergiants
  • Regents Answer
    • (1)Red Dwarfs
  • Regents Question
    • Which list shows stars in order of increasing temperature?
    • (1)Barnard’s Star, Polaris, Sirius, Rigel .
    • (2)Aldebaran, the Sun, Rigel, Procyon B .
    • (3)Rigel, Polaris, Aldebaran, Barnard’s Star .
    • (4)Procyon B, Alpha Centauri, Polaris, Betelgeuse.
  • Regents Answer
    • (1)Barnard’s Star, Polaris, Sirius, Rigel .
  • Star Life Cycles
    • Stars are born in a cloud of gas and dust, called a nebula .
    • Most stars remain as main sequence stars, until their hydrogen fuel is depleted
    • An average star, like the sun, would go through the Red Giant phase, eventually becoming a White Dwarf.
    • A large star would become a Supergiant, then explode as a supernova. The result may be a neutron star, pulsar or black hole.
  •  
    • The sun is a star .
    • A ball of hot glowing gases.
    • It gets hotter as you go deeper.
    • Central force that has a high influence on planets orbits.
    • Without the sun’s energy and heat there would be no life on Earth.
    • It holds everything in place by its gravity .
    • It contains about 99% of the mass of the solar system.
    Sun
  • Sun http://en.wikipedia.org/wiki/Image:Sun920607.jpg Mythology The Sun God. Greeks Called it Hellos Mass 333 400 times the mass of the Earth Diameter 1 392 000 km (109 x Earth’s diameter) Gravity 28 times that on Earth Surface Temperature 6000°C (average). From 4500 to 2000000°C up to 15000000°C in the core. Period of rotation (day) Equator 26 Earth days, poles 37 Earth days Tilt of axis 122°
  • Our Solar System
  •  
  • Solar System Components
    • The Solar System includes:
      • The Sun, a medium size, middle-aged star
      • The eight planets and associated moons
      • Asteroids – chunks of rock found mostly in a belt between Mars and Jupiter
      • Comets – mass of frozen gas and rock
      • These are considered celestial objects which appear in the sky during day and night.
  • Formation of the Solar System
    • 4.6 Billion years ago a large cloud of gas, ice & dust existed
    • Began to contract & slowly rotate
      • Contraction increased density & rotation
      • Gravity began to pull material toward the center
      • Density increases = increased rotation & gravity
      • Begins to form disk with large center
      • Central mass begins to heat up due to contraction
        • Temperatures reach 10 million 0 K
        • Hydrogen atoms begin to fuse together forming Helium
        • Fusion occurs, driving the formation of our Sun
      • The material outside the central mass forms planets
  •  
  • The Parts of Our Solar System
    • The sun is the center of the Solar System
      • Inner Planets: Also called Terrestrial planets: first four planets. They are solid, rock like structures
      • Asteroid belt : band of rocks orbiting the sun
      • Outer Planets: Also called Jovian planets: The 4 planets farthest from the sun
        • 4 are made up of mainly lighter element gases
        • Last two are frozen materials
  • Two Kinds of Planets Planets of our solar system can be divided into two very different kinds: Terrestrial (earthlike) planets: Mercury, Venus, Earth, Mars Jovian (Jupiter-like) planets: Jupiter, Saturn, Uranus, Neptune 0
  • Size of Terrestrial Planets Compared to Jovian Planets
  • Terrestrial Planets Four inner planets of the solar system Relatively small in size and mass (Earth is the largest and most massive) Rocky surface Surface of Venus can not be seen directly from Earth because of its dense cloud cover . 0
  • The Jovian Planets Much larger in mass and size than terrestrial planets Much lower average density All have rings (not only Saturn!) Mostly gas ; no solid surface 0
  • Asteroids The total mass of all the asteroids is less than that of the Moon. -rocky objects with round or irregular shapes lie in a belt between Mars and Jupiter
  • The Asteroid Belt Pluto Neptune Uranus Saturn Jupiter Mars (Distances and times reproduced to scale) 0 Most asteroids orbit the sun in a wide zone between the orbits of Mars and Jupiter.
  • Asteroids
      • Believed to be a planet that never formed
      • Range in size from dust to almost Moon size
      • Photographed by Galileo probe
        • Some Named Asteroids:
          • Ceres: 940 km (Largest known)
          • Pallas: 523 km
          • Vesta: 501 km
          • Juno: 244 km
          • Gaspra & Ida
  •  
  •  
  • only visible when they are close to the sun
  • Comets Mostly objects in highly elliptical orbits, occasionally coming close to the sun. Icy nucleus, which evaporates and gets blown into space by solar wind pressure. 0
  • Comet Information:
    • Comet Composition:
      • Dust, rock, frozen methane, ammonia, and water
      • Comets normally look like dirty snowballs
      • When they get close to stars, they change
        • They begin to vaporize & Glow
        • Forms a coma (tail) from the nucleus (head)
          • Coma: glowing trail of particles
          • Always points away from the star
      • Comets eventually break up into space debris
    • Oort Cloud: large collection of comets beyond Pluto
  • shooting stars
  • Meteoroids Small (  m – mm sized) dust grains throughout the solar system If they collide with Earth, they evaporate in the atmosphere . Visible as streaks of light (“shooting stars”): meteors . 0
  •  
  • LARGEST METEORITE TO HIT EARTH – Namibia, Africa
  • Meteoroids, Meteors, & Meteorites
    • Meteoroids: chunks of rock
      • Randomly moving through space
      • Usually leftover comet or asteroid debris
    • Meteor: Meteoroid that enters Earth’s atmosphere
      • Heat up & begin to glow = shooting star
      • Most burn up before reaching the surface
      • Many meteors at one time = meteor shower
    • Meteorite: Meteor that does not totally burn up, & strikes the Earth’s surface
      • Impact creates a crater
  • Cosmic Collision Video Clip
  • The Planets
  • http://solarsystem.jpl.nasa.gov/multimedia/gallery/solarsys_scale.jpg (Distance between objects not to scale)
  • How small are we? source: Celestia (application) (Distance between objects not to scale) Earth
  • How small are we? source: Celestia (application) (Distance between objects not to scale) Earth
  • Relative distance of planets
    • Sun = 1300mm diameter (blown up garbage bag)
    • Mercury = 4.5mm (coffee bean) 54m from Sun
    • Venus = 11.3mm (small blueberry) 101m from Sun
    • Earth = 11.9mm (small blueberry) 139m from Sun
    • Mars = 6mm (pea) 213m from Sun
    image source: Google Earth
  • Relative distance of planets
    • Jupiter = 133.5mm (large grapefruit) 727m from Sun
    • Saturn = 112.5mm (large orange) 1332m from Sun
    • Uranus = 47.7mm (Kiwi) 2681m from the Sun
    • Neptune = 46.2mm (nectarine) 4200m from the Sun
    • Pluto = 2mm (grain of rice) 5522m from the Sun
    image source: Google Earth
  • Relative distance of planets
    • Jupiter = 133.5mm (large grapefruit) 727m from Sun
    • Saturn = 112.5mm (large orange) 1332m from Sun
    • Uranus = 47.7mm (Kiwi) 2681m from the Sun
    • Neptune = 46.2mm (nectarine) 4200m from the Sun
    • Pluto = 2mm (grain of rice) 5522m from the Sun
    image source: Google Earth
    • A planet is a body that is in orbit around the Sun, has enough mass for its self-gravity to overcome forces (nearly round) shape, and clears the neighborhood around its orbit.
    • Planet order (closest to the sun to furthest):
    • MERCURY
    • VENUS
    • EARTH
    • MARS
    • JUPITOR
    • SATURN
    • URANUS
    • NEPTUNE
    PLANETS
    • Position: Closest planet to the Sun.
    • Atmosphere: Like Earth’s moon, very little.
    • Landscape: Many craters, a little ice. Cliffs and valleys present.
    • Temperatures: Super-heated by the sun in the day. At night temperatures reach hundreds of degrees below freezing. (Not as warm as you would think).
    • Year (Full rotation around the sun): 88 days.
    • Moons: 0
    • Rings: 0
    Mercury
  • Mercury http://en.wikipedia.org/wiki/Image:Reprocessed_Mariner_10_image_of_Mercury.jpg Mythology God of travel, commerce and thieves Mass 0.056 times that of Earth Moons None Diameter 4878 km ( = 0.38 x Earth’s diameter) Surface Similar to Earth’s moon Gravity 0.38 times that on Earth Surface Temperature – 170°C to 430°C Period of rotation (day) 59 Earth days Tilt of axis 0° Distance from Sun 0.39 AU (58 million kilometres) Time to orbit Sun (year) 88 Earth days
    • Position: 2 nd planet from the sun.
    • Atmosphere: Thick enough to trap heat, hurricane winds, lightning, and acid clouds.
    • Landscape: Volcanoes and deformed mountains.
    • Temperatures: Intense heat.
    • Year (Full rotation around the sun): 225 Earth days.
    • Moons: 0
    • Rings: 0
    Venus
  • Venus http://en.wikipedia.org/wiki/Image:Venus-real.jpg Mythology Goddess of love and beauty Mass 0.815 times that of Earth Moons None Diameter 12 103 km ( = 0.95 x Earth’s diameter) Surface Extensive cratering, volcanic activity. Gravity 0.9 times that on Earth Surface Temperature 460°C Period of rotation (day) 243 Earth days Tilt of axis 30° Distance from Sun 0.72 AU (108 million kilometres) Time to orbit Sun (year) 225 Earth days
    • Position: 3rd planet from the sun.
    • Atmosphere: Suitable air pressure to have life. Air is made of oxygen.
    • Landscape: The only planet that has liquid on the surface, rocky, land formations.
    • Temperatures: Suitable for life. Ranges from locations on Earth.
    • Year (Full rotation around the sun): 365 Earth days.
    • Moons: 1
    • Rings: 0
    EARTH
  • Earth http://en.wikipedia.org/wiki/Image:The_Earth_seen_from_Apollo_17.jpg Mythology Gaia—mother Earth Mass 1.0 times that of Earth (5 980 000 000 000 000 000 000 000 kg) Moons One (‘the Moon’) Diameter 12 756 km Surface Two-thirds water, one-third land Gravity 1.0 times that on Earth Surface Temperature average 22°C Period of rotation (day) 1 Earth day Tilt of axis 23.5° Distance from Sun 1 AU (150 million kilometres) Time for light to reach Earth 8 minutes Time to orbit Sun (year) 365.25 Earth days
    • Position: 4th planet from the sun.
    • Atmosphere: Thinner air than Earth.
    • Landscape: Frozen water below the surface, rocky, dusty, and has craters.
    • Temperatures: Like Earth, but drier and colder
    • Year (Full rotation around the sun): 687 Earth days.
    • Moons: 2
    • Rings: 0
    Midnight sun on Mars Mars
  • Mars http://en.wikipedia.org/wiki/Image:2005-1103mars-full.jpg Mythology God of war Mass 0.107 times that of Earth Moons 2 (Phobos—diameter 23 km, Deimos—diameter 10 km) Diameter 6794 km ( = 0.53 xEarth’s diameter) Surface Soft red soil containing iron oxide (rust). Cratered regions, large volcanoes, a large canyon and possible dried-up water channels. Gravity 0.376 times that on Earth Surface Temperature – 120°C to 25°C Period of rotation (day) 1.03 Earth days Tilt of axis 25.2° Distance from Sun 1.52 AU (228 million kilometres) Time to orbit Sun (year) 687 Earth days Time to reach Mars 9 months
    • Position: 5th planet from the sun.
    • Atmosphere: Colorful clouds, until it is squished unto liquid. Cold and windy, giant storms.
    • Landscape: Thick super hot soup.
    • Temperatures: Extremely cold at clouds. Extremely hot and cold radiation.
    Jupiter
  • Jupiter http://en.wikipedia.org/wiki/Image:Jupiter.jpg Mythology Ruler of the Gods Mass 318 times that of Earth Moons At least 28 moons and four rings, including the four largest moons: Io, Ganymede, Europa and Callisto. These are known as the ‘Galilean’ moons. Diameter 142 984 km ( = 11.21 x Earth’s diameter) Surface Liquid hydrogen Gravity 2.525 times that on Earth Surface Temperature Cloud top –150°C Period of rotation (day) 9 hours 55 minutes Tilt of axis 3.1° Distance from Sun 5.2 AU (778 million kilometres) Time to orbit Sun (year) 11.8 Earth years
    • Position: 6th planet from the sun.
    • Atmosphere: Composed mostly of gas with no solid surface. Cloud strips.
    • Landscape: No solid surfaces, high pressures turn gas into liquids.
    • Temperatures: Rings made out of water ice, really cold.
    Saturn
  • Saturn http://en.wikipedia.org/wiki/Image:Saturn_from_Cassini_Orbiter_%282007-01-19%29.jpg Mythology God of agriculture Mass 95.184 times that of Earth Moons At least 30 moons and rings in seven bands Diameter 120 536 km (= 9.45 x Earth’s diameter) Surface Liquid hydrogen Gravity 1.064 times that on Earth Surface Temperature – 180°C Period of rotation (day) 10 hours 39 minutes Tilt of axis 26.7° Distance from Sun 9.6 AU (1400 million kilometres) Time to orbit Sun (year) 29.5 Earth years
    • Position: 7 th planet from the sun.
    • Atmosphere: Gets thicker and thicker, until it is squished unto liquid. Cold and windy.
    • Landscape: Layer of superheated water and gases that form bright clouds.
    • Temperatures: Extremely cold at cloud tops and superheated towards the center.
    Uranus
  • Uranus http://en.wikipedia.org/wiki/Image:Uranusandrings.jpg Mythology Father of Saturn Mass 14.54 times that of Earth Moons At least 21 moons and 11 rings Diameter 51 200 km (= 4.01 x Earth’s diameter) Surface Likely to be frozen hydrogen and helium Gravity 0.903 times that on Earth Surface Temperature – 220°C Period of rotation (day) 17 hours 14 minutes Tilt of axis 98° Distance from Sun 19.2 AU (2875 million kilometres) Time to orbit Sun (year) 84 Earth years
    • Position: Furthest from the sun (Cannot see without a Telescope). 8 th planet.
    • Atmosphere: Very Windy, cold clouds, a layer of methane gas (giving it a blue color), storms as large Earth.
    • Landscape: Scientist think it may have an ocean of super hot lava.
    • Temperatures: Cold
    NEPTUNE
  • Neptune http://en.wikipedia.org/wiki/Image:Neptune.jpg Mythology God of the sea Mass 17.15 times that of Earth Moons 8 moons and 5 rings Diameter 49 528 km ( = 3.88 x Earth’s diameter) Surface Frozen hydrogen and helium Gravity 1.135 times that on Earth Surface Temperature – 220°C Period of rotation (day) 16 hours 7 minutes Tilt of axis 29.3° Distance from Sun 30.1 AU (4500 million kilometres) Time to orbit Sun (year) 165 Earth years
    • Pluto is NOT considered a planet anymore!
    • It is classified as a dwarf planet .
    • Temperatures: Extremely cold, covered with frost.
    • Year (Full rotation around the sun): 248 Earth years.
    • Moons: 3
    • Pluto is very hard to see, if with a really powerful teloscope.
    Think of Pluto as Disney’s dog, NOT a planet! Pluto
  • The planets to scale. The rings of the gas giants are not shown.
  • http://www.solarviews.com/cap/misc/obliquity.htm Comparing tilt of axis
  • Draw a line across the table between the terrestrial and jovian planets and label.
  • Which are more dense? Jovian or terrestrial
  • Which have more moons ? Jovian or terrestrial
  • Which have longer periods of revolution? Jovian or terrestrial
  • Which are larger in size on average ? Jovian or terrestrial
  • Which planet has the longest day ? Venus
  • Which planet has the longest year? Neptune
  • Regents Question
    • Which object in our solar system has the greatest density?
    • Jupiter (3) the Moon
    • Earth (4) the Sun
  • Regents Answer
    • (2) the Earth
    • What is the solar system (what objects make up the Solar System?
    • Draw a diagram of planet placement and list the planets in order from the closest to the furthest from the sun.
    • When did the solar system form?
    • When did the universe form?
    • What is the difference between the Jovian and Terrestrial planets?
    • What is the difference between a meteor, meteoroid, and meteorite?
    • What is your favorite planet and why?
    Review Questions and Concepts:
  • Planetary Orbits Pluto Neptune Uranus Saturn Jupiter Mars Earth Venus Mercury Do Now: Make 3 observations about this animation (Distances and times reproduced to scale) 0
  • http://solarsystem.jpl.nasa.gov/multimedia/gallery/vis_orb.jpg
  • http://solarsystem.jpl.nasa.gov/multimedia/gallery/outer_orb.jpg
  • How the planets move
    • The four innermost planets orbit the Sun in almost circular orbits
    • The larger outer planets move in more elliptical or oval orbits
    • All planets move in the same plane (a large imaginary flat surface)
  • Planetary Orbits Pluto Neptune Uranus Saturn Jupiter Mars Earth Venus Mercury All planets in almost circular (elliptical) orbits around the sun, in approx. the same plane (ecliptic). Sense of revolution: counter-clockwise Sense of rotation: counter-clockwise (with exception of Venus, Uranus, and Pluto) Orbits generally inclined by no more than 3.4 o Exceptions: Mercury (7 o ) Pluto (17.2 o ) (Distances and times reproduced to scale) 0
  •  
  • Planetary Orbits Tipped over by more than 90 0 Mercury and Pluto: Unusually highly inclined orbits 0
  • Orbits
    • Revolution – the movement of an object around another object
    • Orbit – the path taken by a revolving object
    • Celestial objects have elliptical orbits
  • Elliptical Orbit
    • A circle has one central point, called a focus.
    • Ellipses have two points, called foci .
  • Eccentricity
    • The eccentricity of an ellipse is how much it varies from a true circle.
    • The smaller the number, the closer the orbit is to a perfect circle.
    • Formula for eccentricity:
      • Eccentricity = distance between foci
      • length of major axis
  • Calculate the eccentricity of the ellipse below: Formula: eccentricity = distance between foci length of major axis length of major axis
  • Regents Question
    • Which object is located at one foci of the elliptical orbit of Mars?
    • (1)the Sun (3)Earth
    • (2) Betelgeuse (4)Jupiter
  • Regents Answer
    • (1)the Sun
  • Regents Question
    • The bar graph below shows one planetary characteristic, identified as X, plotted for the planets of our solar system.
    • Which characteristic of the planets in our solar system is represented by X?
    • (1)mass (3)eccentricity of orbit
    • (2)density (4)period of rotation
  • Regents Answer
    • (3)eccentricity of orbit
  • Regents Question
    • Which planet has the least distance between the two foci of its elliptical orbit?
    • (1)Venus (3)Mars
    • (2)Earth (4)Jupiter
  • Regents Answer
    • (1)Venus
  • Laws of Planetary Motion
    • Devised by German astronomerJohannes Kepler:
      • The planets move in elliptical orbits, with the Sun at one focus
      • The line joining the Sun and a planet sweeps equal areas in equal intervals of time
      • The square of the time of revolution (T²) is proportional to the planet’s mean distance from the Sun (R³)
  • Kepler’s First Law
    • Planets move around sun in elliptical orbits.
    • Sun is at one focus point.
    • Flatness called eccentricity
    • Formula in ESRT.
    Sun Focus points Major axis Eccentricity = Distance between foci Length of major axis The smaller the number, the closer the orbit is to a perfect circle.
  • Kepler’s Second Law Area of orange section is equal. Distance along orbit is not the same. But the time covered is equal. Planets moves faster when closer to the Sun. Planet moves slower when farther away to the Sun. Caused by gravitational pull of the Sun. eccentricity website
  • Kepler's Third Law The greater the distance from the sun, the longer the period of revolution. Not drawn to scale. Earth – 150 mill. Km, 365 days Mars – 228 mill. km, 687 days
    • Two reasons
    • Longer orbits
    • Slower orbital velocities.
  • Orbital Energy
    • Gravitation – the force of attraction between 2 objects
    • Inertia – the tendency of an object in motion to continue in motion along a straight path
    • The interaction of gravity and inertia keep planets in orbit
  • Energy Transfer
    • Energy is transferred between potential and kinetic as a planet orbits the Sun.
  • Orbital Velocity
    • The Earth’s orbital velocity is highest when kinetic energy is the highest.
    • This occurs when the Earth is nearest to the Sun in its orbit.
  • When does a planet move slowest in its orbit? When does a planet move fastest in its orbit? When furthest from Sun When closest to Sun
  • How are the orbits of the planets described? slightly, eccentric ellipse eccentricity website
  • Which planet has the least perfectly circular orbit? Mercury
  • Which planet has the most perfectly circular orbit? Venus
  • Models of the Solar System
    • Based upon observations of the apparent motion of celestial objects.
    • Geocentric Model – Earth is the center of the solar system, and all objects revolve around it.
    • Used epicycles (small sub-orbits) to explain retrograde (backward) motion of planets
  • Explain the difference between the geo- and helio-centric models of the solar system. Helio-centric Geo-centric Earth- centered Sun- centered
  • Models of the Solar System
    • Heliocentric Model – The Sun is at the center, and the planets revolve around it
    • The planets’ orbits are governed by Kepler’s Laws:
      • Elliptical orbits
      • Velocity changes during revolution
      • Planets further from Sun revolve slower
  • Geocentric vs. Heliocentric
  • Earth Motions
  • Shape of the Sky
    • Dome shaped
    • Latitude = Altitude of Polaris (N. star)
    • You at intersection of N-S, E-W line
    • Zenith- directly above 90°
  • Apparent Daily Motion
    • Celestial objects appear to move in the sky
    • This is due to the Earth’s rotation
    • Objects appear to move 15° per hour, because Earth rotates 360° in 24 hours. 360/24 = 15
  • Earth's Motions How long is one rotation of Earth? How long is one revolution of Earth? One day One year
  • Rotation Revolution Rising and Setting of the Sun Rising and Setting of the Moon The Seasons Changing Constellations Movement of Stars through the sky
  • Regents Question
    • Which observation provides the best evidence that Earth revolves around the Sun?
    • (1)The constellation Orion is only visible in the night sky for part of the year.
    • (2)The North Star, Polaris , is located above the North Pole for the entire year.
    • (3)The sun appears to move across Earth’s sky at a rate of 15 ○ /hr.
    • (4)The Coriolis effect causes Northern Hemisphere winds to curve to the right.
  • Regents Answer
    • (1)The constellation Orion is only visible in the night sky for part of the year.
  • How do you calculate Earth's rate of rotation? One rotation = 360° Time for one rotation = 24 hours 360° ÷ 24 = 15°/hr
  • Regents Question
    • Earth’s rate of rotation is approximately
    • (1)1 ○ per day (3) 180 ○ per day
    • (2)15 ○ per day (4) 360 ○ per day
  • Regents Answer
    • (1)15 ○ per day
  • Star trails looking North Polaris Stars are so far away the appear stationary (not moving). Why do they have this pattern? Earth is rotating.
  • Constellations are groupings of stars that make an imaginary image in the night sky. They have been named after mythological characters, people, animals and objects. In different parts of the world, people have made up different shapes out of the same groups of bright stars. It is like a game of connecting the dots. In the past constellations have became useful for navigating at night and for keeping track of the seasons.
  • Regents Question
    • Which object is closest to Earth?
    • (1)The Sun (3)the moon
    • (2)Venus (4)Mars
  • Regents Answer
    • (3)the moon
  • Apparent Solar Motion
    • The sun appears to move across the sky, like all celestial objects.
    • The sun’s apparent path in the sky varies by latitude and season.
  • Regents Question
    • If Earth’s axis were tilted less than 23.5 ○ , which seasonal average temperature change would occur in New York State?
    • (1)Spring and fall would be cooler.
    • (2)Spring and fall would be warmer.
    • (3)Winter would be cooler.
    • (4)Summer would be cooler.
  • Regents Answer
    • (4)Summer would be cooler.
  • How many degrees did the stars move from diagram 1 to diagram 2? 30° (2 hours x 15°)
  • How can you find Polaris? It’s the only one that didn’t move
  • What hemisphere must you be in? Why? Northern Because Polaris can only been seen in the North
  • What direction must you be looking? North
  • What direction do the stars appear to move?
  • What causes the stars appear to move?
  • Regents Question
    • In the Northern Hemisphere, planetary winds blowing from north to south are deflected, or curved, toward the west. This deflection is caused by the
    • (1)unequal heating of land and water surfaces.
    • (2)movement of low-pressure weather systems.
    • (3)orbiting of Earth around the Sun.
    • (4)spinning of Earth on its axis.
  • Regents Answer
    • (4) spinning of Earth on its axis.
  • Evidence for Rotation Foucault Pendulum Coriolis Effect
  • Regents Question
    • Earth’s rate of rotation is approximately
    • (1)1 ○ per day (3) 180 ○ per day
    • (2)15 ○ per day (4) 360 ○ per day
  • Regents Answer
    • (1)15 ○ per day
  • Regents Question
  • Regents Question
    • The diagram below shows how Earth is illuminated [lighted] by the Sun as viewed from above the North Pole.
    • In which orbital position would Earth be illuminated as shown?
    • (1)A (3) C
    • (2)B (4) D
  • Regents Answer
    • (1)A
  • Four Seasons Name the four seasons and their starting date.
    • Summer Solstice– June 21
    • Autumn Equinox– September 21
    • Winter Solstice– December 21
    • Spring Equinox – March 21
  • What changes do we observe during seasons? Sun’s altitude changes with the season. Highest – June 21, Lowest – Dec. 21, But NEVER overhead at our latitude.
  • What changes do we observe during seasons? Sun rise and Sun set positions change with the seasons. South of E/W in fall and winter. North of E/W in spring and summer. Sun rise in DC
  • What changes do we observe during seasons? Day length – Duration of Insolation Longest on Summer Solstice, June 21. Shortest on Winter Solstice, Dec. 21 12 hours on Equinox for all.
  • What changes do we observe during seasons? What to know about the Summer Solstice.
    • June 21, longest day of the year.
    • Sun at highest altitude at noon.
    • 24 hrs of daylight at North Pole.
    • Direct sun ray at 23.5° north latitude.
    • Sun rise – NE, Sun set - NW
  • What changes do we observe during seasons? What to know about the Winter Solstice.
    • Dec. 21, shortest day of the year.
    • Sun at lowest altitude at noon.
    • 24 hrs. of darkness at North Pole.
    • Direct sun ray at 23.5° south latitude.
    • Sun rise – SE , Sun set – SW
  • What changes do we observe during seasons? What to know about the Equinox.
    • Sept. 21 and March 21.
    • 12 hrs of daylight, 12 hrs of night.
    • Direct sun ray at Equator.
    • Sun rise – E, Sun set – W.
  • Is distance important to seasonal change? NO! Farthest away on July 4, Closest on Jan. 3. Earth’s orbit is an ellipse.
  • Reasons for the Seasons Video Clip
  • Regents Question
  • Regents Question
    • Which position of Earth represents the first day of summer in the Northern Hemisphere?
    • (1)A (3) C
    • (2)B (4) D
  • Regents Answer
    • (3) C
  • Regents Question
  • Regents Question
    • How many degrees will the Sun’s vertical rays shift on Earth’s surface as Earth travels from position C to position D?
    • (1)15 ○ (3) 47 ○
    • (2)23.5 ○ (4) 365 ○
  • Regents Answer
    • (2) 23.5 ○
  • The Moon
  • The Moon
    • The Moon is Earth’s only natural satellite
    • It is estimated to be about 4.5 billion years old
  • What are these? Why so many? Why is Earth not like this? Craters No atmosphere weathering, erosion, atmosphere
  • Features
    • The Moon’s interior is thought to have layers, similar to earth
    • The Moon’s surface is covered with craters, caused by meteor impacts.
  • The Moon’s Surface
    • Dark areas called Maria (from Latin mare, meaning sea). These are ancient lava flows.
    • Light areas are Lunar Highlands , which are mountain ranges made of lighter color rocks.
  • Moon Rocks
    • Rocks on the Moon are made of minerals similar to those on Earth.
  • Rotation and Revolution
    • The Moon’s periods of rotation and revolution are both 27.33 days. The result is that the same side of the Moon always faces Earth (the near side).
    • However, it takes 29.5 days for the Moon to completely revolve around the Earth
  • Why Two More Days? Moon’s orbit Earth moving around Sun. Earth Moon Moon has to revolve for 2 more days to get back to the new moon phase. This occurs because the Earth is revolving around the Sun.
  • Dark Side/Light Side
  • Changes in Shape
  • Phases of the Moon
  • Phases
    • Moon Phases are apparent changes in shape due to the position of the Moon in its orbit.
    • Phase names:
      • New
      • Crescent
      • Quarter
      • Gibbous
      • Full
    • Waxing – becoming more visible
    • Waning – becoming less visible
  • Phases Of The Moon
  • What causes the phases of the moon? The moon's revolution around Earth.
  • How long does one revolution of the moon take? 27.3 days How long does one rotation of the moon take? ESRTs p15
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  • Regents Question
    • Which sequence of Moon phases could be observed from Earth during a 2-week period?
  • Regents Answer
  • What phenomenon does this explain? We only ever see one side of the moon.
  • Why does the moon rise later each day? because as the Earth rotates, the moon revolves
  • What phase of the moon is this? New Gibbous New Crescent 3rd Quarter
  • How many hours is the moon visible each day? 12 hours Approximate Times of Moonrise and Moonset     moonrise     moonset new moon 06:00 AM 06:00 PM waxing crescent 09:00 AM 09:00 PM first quarter 12:00 PM 12:00 AM waxing gibbous 03:00 PM 03:00 AM full moon 06:00 PM 06:00 AM waning gibbous 09:00 PM 09:00 AM third quarter 12:00 AM 12:00 PM waning crescent 03:00 AM 03:00 PM new moon 06:00 AM 06:00 PM
  • What is "waxing"? more of the moon's surface can be seen
  • What is "waning"? less of the moon's surface can be seen
  • The phases of the moon are what type of event? Cyclic
  • Tides & Eclipses Astronomy
  • Tides
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  • What causes tides?
  • Moon’s Effect on Tides
    • Tides are the periodic rise and fall of the ocean surface
    • Tides are caused by the gravitational attraction of the Moon and the Sun on ocean water
    • High tide will occur when the Moon is overhead, as well as on the opposite side of the Earth.
  • Tides High High Low Low Caused by Moon’s gravity pulling Earth’s water. Two of each because the Earth rotates. Tides always High in line with Moon. Earth
  • Regents Question
    • The change in the tides as shown on the graph is primarily the result of
    • Earth’s rotation and the Moon’s revolution
    • Earth’s rotation and revolution
    • The Moon’s rotation and Earth’s revolution
    • The Moon’s rotation and revolution
  • Regents Answer
    • Earth’s rotation and the Moon’s revolution
  • During which phases of the moon do neap and spring tides occur?
  • Neap? 1st & 3rd Quarters
  • Spring? New or Full Moon
  • Phases and Tides
    • The alignment of the Moon with the Sun affect tides.
    • At the full and new moon phase, both are in line, causing a higher high tide and a lower low tide. This is called the Spring Tide.
    • At the quarter phases, the Sun and Moon work against each other, resulting in weaker tides, called Neap Tides.
  • Spring and Neap Tides Sun Sun Neap Tide Spring Tide Quarter Phase – not a large change from high to low tide. New and Full Phase – big change from high to low tide. Water being pulled in two directions. Moon and Sun’s gravity pulling in one direction. Earth Earth
  • How many tides a day? 2 high tides 2 low tides
  • Why are there not exactly 12 hours between tides? because the moon revolves around the Earth while the Earth rotates
  • Regents Question
    • What is the main reason that the gravitational attraction between Earth and the Moon changes each day?
    • Earth’s axis is tilted at 23.5 ○ .
    • Earth’s rotational speed varies with the seasons.
    • The moon has an elliptical orbit.
    • The moon has a spherical shape.
  • Regents Answer
    • The moon has an elliptical orbit.
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  • Eclipses and Conclusions Video Clip
  • Eclipses
    • An eclipse occurs when the Sun’s light is blocked from either the Earth or the Moon.
    • Since the orbit of the Earth and the Moon are along different planes, eclipses don’t happen frequently.
  • What’s the difference between solar and lunar eclipses? Solar Lunar Earth goes into moon’s shadow moon goes into Earth’s shadow
  • Solar Eclipse
    • Solar Eclipse – occurs when the Moon blocks the Sun’s rays from reaching Earth. It occurs only at new moon phase.
  • Solar Eclipse Sun’s Rays Penumbra Umbra
    • Only occurs during the new moon phase.
    • Only total eclipse if in the umbra. Only a few people see it.
    • Moon blocks light to the Earth. Occur less often than lunar.
    Solar Eclipse Photo
  • Lunar Eclipse
    • Lunar Eclipse – occurs when the Earth blocks the Sun’s rays from reaching the Moon. Only occurs at full moon phase.
  • Lunar Eclipse Umbra Penumbra Sun’s Rays
    • Can only occur during the full moon phase.
    • Earth blocks light to the moon.
    • Moon must be in Umbra for a Total Lunar Eclipse.
    • Does not occur that often, moon orbit is tilted.
    Every one on the night side sees the eclipse.
  • Solar Eclipse 2010
  • Solar Eclipses through 2020
  • Lunar Eclipse What phase? Full Moon
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  • Lunar Eclipse 2010
  • Why don’t we have solar and lunar eclipses every month? The moon’s orbit is tilted 5° from the Earth’s orbit.
  • Are We Alone?
  • Home Sweet Home You are here!