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The Universe

The Universe. LO: Describe the Earth-Moon System SLE: Meet or exceed NGSS Checkpoint Quiz on the Moon and Earth:. 1.) What causes the moon to have phases, as seen from Earth? 2.) Name the phase shown at right  3.) Why can we only see one side of the moon from Earth?

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The Universe

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  1. The Universe

  2. LO: Describe the Earth-Moon System SLE: Meet or exceed NGSSCheckpoint Quiz on the Moon and Earth: 1.) What causes the moon to have phases, as seen from Earth? 2.) Name the phase shown at right  3.) Why can we only see one side of the moon from Earth? 4.) Explain the difference between a solar eclipse and a lunar eclipse. 5.) Why can solar eclipses only been observed on certain parts of the earth, and not all of Earth at once?

  3. LO: Describe the motion of the Earth and Moon SLE: Meet or exceed NGSS Checkpoint Quiz on Earth/Moon Motion: • Describe why the moon has phases, as seen from Earth. • Why does the earth have seasons? • Draw a diagram that shows the relative positions of the earth and sun during the four seasons. (Include the position of the earth’s axis.) • Among these cities, on December 22, which city has the greatest number of daylight hours: Seattle, Honolulu, or Sydney, Australia? • During which time of year is the South Pole in darkness all day long?

  4. LO: Describe historical models of the solar systemSLE: Meet or exceed NGSS Checkpoint Quiz on Models of the solar system: • What motivated ancient astronomers before the Greeks to study the stars and planets? • Who first proposed a geocentric model of the solar system? • Why did the Greeks reject Aristarchus’ model of the solar system? • List two of Galileo’s discoveries that provided evidence for the heliocentric model of the solar system. • Draw a basic diagram of Artistotle’s model of the solar system. Label the sun, the earth, the moon, and the stars. (The other planets don’t have to be in any particular order for this question.)

  5. Tools of Astronomy: Optical Telescopes: Use visible light to examine objects not visible to the naked eye. Types of optical telescopes: • Refracting: Uses two glass lenses connected by a tube. • Reflecting: uses mirror to gather light and concentrate it at a single location.

  6. Optical Telescopes in Space: On Earth, magnification in very large telescopes is limited because the atmosphere refracts light. To solve this problem, starting in the 1990s, robot telescopes have been placed in orbit above the atmosphere.

  7. Using Non-Visible Parts of the Electromagnetic Spectrum: Beginning in the early 1900’s, astronomers have used parts of the electromagnetic spectrum not usually detected by human senses, using these tools: • Radio telescopes: allows us to detect total energy produced by stars • Infrared photography: allows us to see into gas clouds • Spectroscopes: allow us to calculate the motion of stars and galaxies, and to determine the composition of stars and planets. • X-rays: allows us to detect very powerful events like supernovae and the creation of black holes.

  8. Using spectroscopes and optical telescopes, and a knowledge of the Doppler Effect, in 1922 American astronomer Edwin Hubble was able to discover that the universe is rapidly expanding.

  9. Homework: LO: Identify and describe tools used by modern astronomers. SLE: Meet or exceed NGSS • Read p. 8-13 • Respond to review questions on p. 13

  10. Moons of Our Solar System: Natural or man-made objects that orbit around planets are called satellites. If the satellite is large enough to have enough gravity to be spherical, it’s called a moon.

  11. Earth’s Moon: Features of Earth’s moon: Age: about 4.5 billion years (Earth is 4.6 billion years old) Composition: rock that is identical to Earth’s rock. Surface: Covered with low mountains, smooth plains and impact craters from meteors. Atmosphere: none Mass: 1/6 of Earth’s mass (16%) Surface temp: -170 to 134 C Period of rotation: 28 days Period of revolution: 28 days

  12. The origin of the moon: The rock found on the moon is chemically identical to the rock on Earth. Scientists currently believe that, early in Earth’s history, a massive asteroid collided with Earth. Some of Earth’s molten material was ejected into orbit around Earth, and when it cooled it became our moon.

  13. Phases of the moon:

  14. Eclipses: Lunar Eclipse: When the earth comes between the sun and the moon and casts its shadow on the surface of the moon. Solar Eclipse: When the moon comes between the earth and sun and casts its shadow on part of the earth.

  15. Moons of other planets: Mars: 2 moons, Phobos and Deimos Jupiter: 67 at last count. The most massive of these, Ganymede, Callisto, Io and Europa, were discovered by Galileo and are called Galilean satellites. Io is very close to Jupiter, and the gravitational tug causes it have almost constant volcanic eruptions.

  16. Saturn: 62 moons at last count. One of them, Titan, is the largest moon in the solar system. Another moon, Enceladus, is covered in frozen water. Methane eruptions from Enceladus is probably the cause of Saturn’s rings.

  17. Homework: LO: Describe moons of our solar system SLE: Meet or exceed NGSS • Read p. 110-116 • Review questions p. 117

  18. LO: Describe the planets of our solar system. SLE: Meet or exceed NGSS Checkpoint quiz on moons and the solar system: • List the planets in order, starting from the sun and going outwards. • Which planets of the solar system are gas giants? • Draw and label all the phases of the moon, starting with a new moon and ending with a full moon. • Why can we never see the “back” side of the moon? • Describe the origins of the moon (the one that goes around the earth).

  19. LO: Describe the planets of our solar system: SLE: Meet or exceed NGSS Checkpoint Quiz on the Planets: 1.) Name the planet to the right. 2.) Why is Venus hotter than Mercury? 3.) What is Jupiter mostly made of? 4.) What is the main gas in Mars’s atmosphere? 5.) Name the planets of our solar system in order, starting from the sun and moving outward.

  20. Cause of Seasons on Earth:

  21. LO: Model features of the Earth-Moon-Sun planetary system SLE: Meet or exceed NGSS Modeling the motion of the Earth: • Draw a color diagram that shows the Earth’s motion around the sun. Place the earth’s axis correctly in its orbit, and show which part of the earth is in sunlight or darkness. Include the dates of the solstices and equinoxes. • Answer these questions about this model: • During what part of the year is the north pole in total darkness? • During what part of the year does the northern hemisphere have the greatest number of daylight hours? • On June 22, which city has shorter days, Mexico City, Seattle, or San Francisco? Why? • During which part of the year does the whole earth have about the same number of daylight hours? • On what day does Seattle have its shortest day?

  22. Human Space Exploration: Rockets: So far, rockets are the only vehicles that humans have made that can produce enough acceleration (for its mass) to escape Earth’s gravity. Escape Velocity: To escape the gravitational pull of the earth, an object must travel at a velocity of 11 km/s. Orbital Velocity: To maintain a sustainable orbit around the earth, an object must be traveling at a velocity of at least 8 km/s.

  23. How Rockets Work (Thank you, Isaac Newton):

  24. Artificial Satellites: Human-made satellites are launched into space by rockets, and perform many useful tasks: • Monitor weather patterns • Track movement of tectonic plates • GPS • Communications • Military surveillance • Monitor health of crops, forests and ocean ecosystems • Space Telescopes

  25. Types of Satellite Orbits: • Low Earth Orbit (LEO): The satellite travels a few hundred Km above the earth. This allows satellites to get clear images of Earth, but they are out of communication much of the time.

  26. Polar Orbit: A LEO that goes around the earth over the poles Geostationary Orbit (GSO): The satellite orbits the earth at the same speed as the earth’s rotation, so that it stays over the same spot all the time. GSOs are much higher than LEOs.

  27. Deep Space Probes: Except for the moon, all human exploration of space so far has been with robotic space probes. The first space probe was sent to the moon in 1959. By 2012, space probes had been sent to every planet in the solar system.

  28. Timeline of Human Space Exploration: • 1926: Robert Goddard (USA) launches first successful liquid fuel Rocket. • 1944: German V2 rocket becomes first manmade object to leave Earth’s atmosphere • 1957: USSR launches Sputnik, first artificial satellite into orbit around Earth.

  29. 1957: USSR launches first animal into orbit, the dog Laika • 1959: First space probe to the Moon, Luna 1 (also the first object to leave Earth orbit) • 1961: US launches first primate into space (Ham, a chimp) • 1961: USSR launches first human into orbit • 1963: First woman in space (USSR)

  30. 1969: First human on Moon (USA) 1971: First probe to Orbit Mars (Mariner 9, USA) 1974: First probe to Venus and Mercury (Mariner 10, USA) 1976: First probe lands on Mars (Viking, USA) 1986: First space station (Mir, USSR) 1991: First orbit of Jupiter (Galileo, USA) 1998: International space station launched 2012: First human-made object to leave the solar system (Voyager 1, USA) 2015: First probe to Pluto (New Horizons, USA)

  31. Obstacles to Human Deep Space Travel: Human deep space travel is very difficult and dangerous because: • Humans need water, air, air pressure, fuel warmth and food enough to last several years. • Small meteors can destroy any space ship humans are capable of building. • Weightlessness in deep space can cause permanent decay in muscles and bone mass • Long-term exposure to the sun’s radiation will eventually kill the travelers • Maintaining mental health will be difficult in a small, cramped space with a few other people for as long as several years.

  32. LO: Describe how and why humans explore space SLE: Meet NGSS Checkpoint quiz on space exploration: • How fast do rockets need to go to escape Earth’s gravity? • Draw and label a diagram of the interior of a liquid fuel rocket. • List three uses for artificial satellites. • What is a geostationary orbit? • What is the name of the first human-made object to orbit the earth?

  33. LO: Identify ways that humans have explored space SLE: Meet or exceed NGSS Homework: • Read and take notes on p. 134-143 • Review questions p. 137 (due Monday)

  34. Life Cycle of Large and Small Stars:

  35. Homework: LO: Describe the life cycle of large and small stars SLE: Meet or exceed academic standards • Read p. 40-45 • Draw a color diagram of the life cycle large and small stars. Include a title (The Life Cycle of Stars), the name of each stage, a picture of the star at each stage, and 1-2 sentences about what happens to the star at each stage.

  36. How to find distances to stars: Method 1: Parallax: For nearby stars, the distance can be used by measuring the angle of shift of the star against a background of more distant stars, and then using trigonometric ratios to calculate the distance. This is very accurate, but only works for nearby stars (less than 30,000 light years away)

  37. Method 2: Cepheid variables: • A class of stars called Cepheid variables varies in light intensity in regular time intervals • The period of the light variability and the actual brightness of the star are directly proportional and are uniform among all of these kinds of stars. • Once the period is known, the apparent brightness of the star can be compared to the absolute brightness to calculate the distance to the star. • These stars can be used as “mile markers to estimate the distance to stars that are near the cepheid variable.

  38. LO: Describe the characteristics of starsSLE: Meet or exceed NGSS Checkpoint Quiz on Stars: • Describe the life cycle of a smaller star, like the sun. Name each stage of the life cycle, and give a brief, one-sentence description of what happens at each stage. (4 points) • List two ways that astronomers can tell how far away a star is. (2 points)

  39. Regions of Black Holes:

  40. LO: Describe characteristics of black holes. SLE: Meet or exceed NGSS Checkpoint Quiz on Black Holes: 1.) How are black holes formed? 2.) Why are black holes black? 3.) What is at the very center of a black hole? 4.) What is the “boundary” of a black hole, beyond which light cannot escape? 5.) Will the sun become a black hole at some point in the future? Why or why not?

  41. Cosmology: looking at the universe all at once Cosmology: the study of the structure, origin, and eventual fate of the universe as a whole. Two major cosmological theories: • Steady State Theory: The universe has always existed in more or less its current state, and always will. (most accepted until 1960s-1970s)) • Big Bang (Inflation) Theory: The universe began as a singularity, and suddenly expanded outwards (currently most accepted theory).

  42. Things to keep in mind about the Big Bang: • The Big Bang (inflation) began about 13.8 billion years ago, and is still occurring. • At the level of galaxies and smaller, gravity is a much stronger influence than inflation. • The universe is not expanding into a pre-existing space; space itself is expanding. (At the beginning of the big bang, the total volume of the universe was zero.)

  43. Evidence for the Big Bang: • Hubble‘s observations of the red shift of distant galaxies can only be explained by an expanding universe. • In the 1960s, two engineers (Arno Penzias and Robert Wilson) accidentally discovered background microwave radiation left over from the big bang: https://www.youtube.com/watch?v=1kqWWLpyMpY 3. Recent observations of older (more distant) galaxies reveal that they contain far fewer heavy elements than newer (closer) galaxies.

  44. Eventual Fate of the Universe: The eventual fate of the universe depends on the total amount of mass and energy in the cosmos: • If the mass is high and energy is low, gravity will eventually cause the exapansion to reverse itself (Big Crunch) • If current expansion continues (mass and energy both low), eventually the galaxies will grow too far apart, new stars will no longer form, and eventually the universe will dissolve into a spread-out expanse of black holes and gas remnants (Big Freeze) • If expansion accelerates (mass is low and energy high), most of the known universe will suddenly race out ahead of our event horizon (Big Rip). Most recent observations support the Big Rip.

  45. LO: Describe theories of the creation and end of the universe SLE: Meet or exceed NGSS Homework: • Read p. 50-53 • Review questions p. 53

  46. LO: Describe the origin and fate of the cosmos. SLE: Meet or exceed NGSS Checkpoint Quiz on the Big Bang: • Describe the Big Bang Theory. • List and describe two observations that give evidence of the Big Bang. • About how old is the universe? • What did astronomers think about the origin and fate of the universe before the Big bang theory was accepted? • Based on recent observations, which end of the universe is most likely: Big Crunch, Big Freeze, or Big Rip?

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