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Astronomy

Astronomy. 1.1.1 explain how the formation of the solar system created the sequence of bodies and the relative motion that defines our solar system explain the hierarchy of the solar system compared to the universe

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Astronomy

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  1. Astronomy

  2. 1.1.1 explain how the formation of the solar system created the sequence of bodies and the relative motion that defines our solar system • explain the hierarchy of the solar system compared to the universe • 1.1.2 explain how the relative motions of the earth, sun and moon cause ocean tides • explain the reason that Earth has four seasons based on the tilt of Earth’s axis of rotation and Earth’s motion relative to the sun • relate Earth’s initial formation to its present day spherical shape • 1.1.3 explain how the sun produces energy which is transferred to the Earth by radiation • 1.1.4 explain how incoming solar energy makes life possible on Earth

  3. 1.1.1 be able to describe the motions of precession and nutation & their effect on Earth’s orbit around the sun be able to describe Earth’s primary motions relative to those of the solar system and galaxy be able to demonstrate how bodies in space both create and are affected by the gravitational attraction of adjacent bodies resulting in elliptical orbits be able to explain barycenter 1.1.2 be able to demonstrate the relative positions of Earth to the sun during different seasons 1.1.3 identify combustion and burning objects describe, compare and contrast nuclear fusion and fission be able to explain the equilibrium between gravity and particle motion in the core of a star navigate the electromagnetic spectrum and identify features of associated wave energy 1.1.4 explain how the seasons are a result of the Earth’s tilted axis and the amount of solar energy that Earth receives

  4. The Sun-Earth-moon system

  5. Tools of Astronomy • Light – electromagnetic radiation • Visible light (what humans can see) • Infrared • Ultraviolet • Radio waves • Microwaves • X rays • Gamma rays

  6. Electromagnetic radiation is arranged by wavelength and frequency • Can be classified by either wavelength or frequency • Frequency and wavelength are related c = λf • c = speed of light = 3.0 x 108 m/s • f = frequency λ = wavelength

  7. Telescopes • 3 benefits: • Can attach different detectors to observe all wavelengths • Brings much more light into focus than the human eye • Allow use of specialized equipment • 2 types: • Refracting: use lenses to focus light • Reflecting: use mirrors to focus light

  8. Instruments in Space • Earth’s atmosphere blocks infrared (IR) radiation, ultraviolet (UV) radiation, X rays and gamma rays • Images from wavelengths that do pass through Earth’s atmosphere are blurred • Can allow for close-up observations and collection of samples

  9. THE MOON • Solid, rocky body • Radius is about 27% of Earth’s • Mass is about 1% of Earth’s • Age of the moon is about 3.1 to 3.8 billion yrs

  10. Formation of the Moon • 3 Theories • Capture Theory: during the formation of the solar system a large body got too close to the forming Earth and got trapped by gravitational pull • Simultaneous Formation: moon and Earth formed at the same time in the same area • Impact Theory: a Mars-sized object hit Earth about 4.5 billion yrs ago during the formation of the solar system

  11. Lunar Surface Features • Highlands • Maria • Impact craters • Ejecta and rays • Rilles • Regolith

  12. Sun-Moon-Earth Interactions • Daily Motion • Rotation of the Earth • 15o every hour • Annual Motion • Earth’s orbit along the ecliptic around the Sun • Earth’s tilt • Solstices • Equinoxes • Moon phases • Eclipses

  13. Earth’s Tilt • Earth’s axis is tilted about 23.5o relative to the ecliptic • This along with Earth’s orbit gives us seasons • Causes the Sun’s altitude to change throughout the year • Solstices • Equinoxes

  14. Solstices Summer Solstice – around June 21 Sun is directly overhead at Tropic of Cancer Winter Solstice – around December 21 Sun is directly overhead at Tropic of Capricorn

  15. Equinoxes • Autumnal Equinox – around September 21 • Sun is directly overhead at the equator • Vernal Equinox – around March 21 • Sun is directly overhead at the equator • Length of day and night are the same

  16. Phases of the Moon

  17. Tides • Effect of the Moon’s gravity on Earth • Occur every 12 hours Neap tides lower than normal because the Moon and sun are at right angles to each other Spring tides higher than normal because the Moon and Sun are aligned

  18. Eclipses • Solar • Moon passes between the Earth and Sun • Lunar • Moon passes through the Earth’s shadow

  19. The Solar system

  20. Early Theories • Geocentric Model – theory that the Earth is the center of the solar system • Retrograde motion – when a planet appears to move in the opposite direction (east to west) • Heliocentric Model – developed by Nicolaus Copernicus in 1543 theory that the Sun is the center of the solar system • Tycho Brahe – late 1500s made many accurate observations of planetary positions used by other early astronomers

  21. Johannes Kepler • Developed three laws • Kepler’s 1st Law – planets orbit the Sun in an ellipse (oval shape) • Kepler’s 2nd Law – an imaginary line between a planet and the Sun covers the same amount of area in the same amount of time • Kepler’s 3rdLaw – the size of a planet’s ellipse is related to its orbital period P2 = a3 P = orbital period a = semimajor axis

  22. Galileo Galilei – 1st person to use a telescope • Discovered 4 moons around Jupiter • Isaac Newton – developed the law of universal gravitation F = G F = force (in Newtons) m1 & m2 = mass of the bodies (in kg) G = 6.6726 X 10-11 m3/kg/s2 r = distance between the bodies (in m) • Center of mass – balance point between two orbiting bodies • Between the Earth and the Sun this point is nearly on the Sun’s surface m1m2 r2

  23. Barycenter = center of mass Precession Nutation Rotation

  24. How the Solar System Formed • Collapsing interstellar cloud

  25. Terrestrial Planets • MERCURY Location: closest to the Sun Moons: no moons Atmosphere: very thin, mostly oxygen and sodium Surface: much like Earth’s moon Interior: solid nickel-iron core Day Length: 58.5 Earth days

  26. VENUS Location: 2nd planet from the Sun Moons: no moons Atmosphere: thick, mostly carbon dioxide Surface: relatively smooth due to lava flows Interior: liquid metal core Day Length: 243 Earth days

  27. EARTH Location: 3rd planet from the Sun Moons: one moon Atmosphere: thick, mostly oxygen and nitrogen Surface: life sustaining Interior: solid nickel-iron core Day Length: 24 hours

  28. MARS Location: 4th planet from the Sun Moons: 2 moons – Phobos, Deimos Atmosphere: thin & windy, mostly carbon dioxide Surface: craters in the south, plains in the north, ice caps at both poles Interior: solid nickel-iron core Day Length: almost 25 Earth hours

  29. Gas Giants • JUPITER Location: 5th planet from the Sun; has a ring Moons: 4 major – Io, Europa, Ganymede, Callisto Atmosphere: very thick, mostly hydrogen Surface: no true surface; gas & liquid gas Interior: may have an Earth sized solid core Day Length: 10 Earth hours

  30. SATURN Location: 6th planet from the Sun; has many rings Moons: 1 major - Titan Atmosphere: thick, mostly hydrogen Surface: no true surface, gas & liquid gas Interior: may have a small, solid core Day Length: nearly 11 Earth hours

  31. URANUS Location: 7th planet from the Sun; has 10 rings Moons: 2 major - Titania, Oberon Atmosphere: thick, mostly hydrogen Surface: no true surface, gas & liquid gas Interior: may have a small, solid core Day Length: 17 Earth hours

  32. NEPTUNE Location: 8th planet from the Sun; has 6 rings Moons: 1 major - Triton Atmosphere: thick, mostly hydrogen Surface: no true surface, gas & liquid gas Interior: may have a small, solid core Day Length: 16 Earth hours

  33. PLUTO – a planetoid Location: 9th from the Sun Moons: 1 moon - Charon Atmosphere: thin atmosphere of methane and nitrogen Surface: mix of ice and rock Interior: unknown Day Length: about 6 Earth days

  34. Galaxies and the Universe

  35. Our solar system is in the Milky Way Galaxy

  36. Most scientists believe that there is a massive black hole at the center of our galaxy • It is called Sagittarius A* • It is thought to be about 93 million miles across • It is thought to weigh about the same as 4 billion Suns

  37. Formation of the Universe • Age is about 13.5 billion years • Big Bang Theory (not the TV show) • Expansion of space and matter • Steady-state theory • Universe looks the same on large scales • New matter is created and added to the universe as it expands

  38. Death of the Universe • Big Crunch – universe stops expanding and then collapses back in on itself • Big Freeze – universe never stops expanding, becomes progressively too cold to support life • Flat Universe – universe stops eventually stops expanding and also becomes too cold for life • Big Rip – rate of expansion is increasing due to dark matter which will eventually tear the universe apart

  39. stars OUR SUN

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