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Unit 3: To Infinity and Beyond! (Space Exploration)
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Space Alphabet In small groups, brainstorm words about space for each letter
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Topic 1: Our Human understanding of space
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Built to mark the summer & winter solstices
2300 BC Neolithic (Stonehenge) Built to mark the summer & winter solstices Sun (as seen from Earth) reaches its: -Southern (strongest) extreme = longest day -June 21 -Northern (weakest) extreme = shortest day -December 21
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2000 BC Aristotle Geocentric (__________-centered) model Earth Stars were attached to outermost sphere Model could forecast phases of the moon Model could not predict planetary motion
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AD Maya Chichen Itza Built to mark the spring and fall Equinox Length of day & night are equal March 21 = spring equinox September 22 = fall equinox
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1530 AD Copernicus Heliocentric (_________-centered) model Sun Able to explain planetary motion
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1600 AD Galileo Galilei New technology - telescope
Observations – mountains on moon, “bumps” on Saturn, spots on Sun Provided evidence to support Copernicus’ theory Still could not accurately predict planetary motion
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Orbits of planets were not circular – they were ellipses
1620 AD Kepler Orbits of planets were not circular – they were ellipses Explained planetary motion in Copernicus’ theory
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Stars A hot, glowing ball of hydrogen gas Gives off light energy
Vary greatly in their characteristics Mass, density, diameter, and color Color of a star depends on surface temperature Hot = blue Cooler = red
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Hertzsprung-Russell Diagram
Graph that compares the surface temperature and brightness of stars Stars fall into distinct groupings
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Life Stages of a Star How the Universe Works - Disk 1
Episode: Extreme Stars (~26.5min) 0:55-16:48 – nebulae, prostar, main sequence 23:40-29:05 – death of sun-like stars 29:06-34:14 – death of massive stars
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1) Nebula Stars are born in regions of space where there are huge accumulations of gas and dust Caused by gravitational attraction between atoms of gas and dust 75% hydrogen, 23% helium, 2% oxygen / nitrogen / carbon / silicon dust
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2) Prostar More material is collected Higher mass Temperature increases Starts to glow
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3) Main sequence Fusion Hydrogen changes to helium Interior of star gets hotter Core reaches °C Releases great quantities of energy and radiation Stars can be classified as SUN-LIKE or MASSIVE based on their mass
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4) Fuel starts to run out Helium starts to fuse with carbon and other elements Outer layers starts to expand and star becomes very bright Turns into: RED GIANT (sun-like) RED SUPER-GIANT (massive)
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6.2 billion years from now the Sun will have become a red giant star
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5) Fusion reaction stops
Core temperature is no longer hot enough to keep reaction going Sun-like star: Star becomes WHITE DWARF Star eventually fades until it is a cold, dark BLACK DWARF
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Gravity causes core to collapse on itself
Massive star: Gravity causes core to collapse on itself Supernova – explosion that marks the death of a massive star Neutron star – core that is left over; also called black hole supernova that was first observed around 1050 AD
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Sun-like star Black Dwarf Nebulae White Dwarf Red Giant Prostar
Supernova Red Super Giant Main Sequence Massive star Black hole (neutron star)
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Star groupings 1. Constellations Groupings of stars that form patterns 88 official constellations Ursa Major, Ursa Minor 2. Asterisms Distinctive star grouping that is not an official constellation Big Dipper
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3. Galaxies Groupings of millions or billions of stars, gas and dust held together by gravity Milky Way Spiral, Elliptical & Irregular galaxies
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Our Solar Neighborhood
Sun Sun-like star
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Solar wind Sun releases charged particles in every direction
Earth is protected by its magnetic field Results in the Northern lights
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Planets 2 distinct groups Inner or Terrestrial Outer or Jovian Smaller
Rocky Close to the Sun Mercury, Venus, Earth Mars Outer or Jovian Larger Gas giants Further from the Sun Jupiter, Saturn, Uranus, Neptune
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Discovered in 1930 Considered the 9th planet until 2006 Now classified as a dwarf planet
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Why? Too far from the sun to be Terrestrial Too small/rocky to be Jovian Additional objects have been discovered that are more massive Has a unique orbit Is inclined Intersects with Neptune’s orbit
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Characteristics of Planets
Smallest? Largest? Earth’s sister? “Red” planet? Can sustain life? Volcanoes? Rings? Hottest? Coldest? 400-yr storm? Closest to sun? Furthest from sun?
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Other Bodies Asteroids Small rocky bodies orbiting the Sun
Found mainly in a narrow belt that separates the Terrestrial and Jovian planets
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Comets “Dirty snowballs” Composed of dust and ice Bright center and long tail Tail is only visible when comet gets close to Sun Materials on comet are heated and gases are released
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Predictable orbits around the Sun
Halley’s Comet – visible every 76 years First seen in 240 BC, last seen in 1986 Next schedule return is 2062
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Meteoroids Small pieces of rocks flying through space with no particular path Usually only aware of as they pass through our atmosphere Meteor (shooting star) Pulled into our atmosphere by gravity Atmospheric friction causes it to give off light Meteorite Hits Earth’s surface
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Vastness of Distance & Time in Space
What unit would you use to measure the: Perimeter of your school? Width of a dime? Width of your desk? Distance from Edmonton to Calgary? Distance from Earth to Mars?
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Astronomical Unit (AU)
Used for measuring “local” space distances Inside our solar system 1 AU = km Average distance from center of Earth to center of the Sun
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Light Years Used to measure distances beyond our solar system Out to stars and galaxies Light travels km/s 1 light year = 9.5 trillion km (distance light travels in one year)
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Light from sun/stars doesn’t instantly reach Earth
You are seeing objects as they was at an earlier time We see the: Moon as it was ~1 second before Sun as it was ~8 minutes before Pluto as it was ~5 hours before Stars as they were ~ years ago Astronomers believe the Hubble Telescope has captured images that date back ~12 million years
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Tracking Celestial Objects
Sundials Measure the length of day & time Track the movement of the sun across the sky using shadows
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Device was aligned with the North Star
Merkhet Device was aligned with the North Star Second one was used to establish a N-S line Used to: Predict movement of stars/objects Tell night The word “merkhet” means “instrument of knowing,” May have been used in construction of temples and tombs to align structures in particular ways A merkhet includes a straight bar attached to a plumb line, a weighted line which can be used to establish a straight vertical line to the ground. To use the merkhet, the device was aligned with the North star, and a second merkhet would be used to establish a North-south meridian. This line could be used to align a structure, or as a reference point to track the movement of stars in the sky. By making note of when particular stars crossed the meridian, the user could determine the time.
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Used to measure a star’s height above the horizon
Quadrant Used to measure a star’s height above the horizon Top right – England, 1388
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Astrolabe Accurate charts of star positions
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Measure the angle between the Moon and any given star
Cross-staff Measure the angle between the Moon and any given star To measure the angle between two stars, an astronomer would place the staff just below one eye (drawing) and slide the cross-piece up and down. The cross-piece would have a pair of open sights sticking out perpendicular to the drawing at symmetric locations such as B and B' (often several pairs of sights, some spaced further apart than others). The astronomer would slide the cross-piece up and down, until sight B covered one of the stars and sight B' the other. For use at night, slits make convenient sights (see below). After that was achieved, the instrument would be lowered and the distance AC would be measured. Then if A was the angle between the staff and the direction of one star, from the definition of the tangent tanA = BC/AC The distance BC between the sight and the stick was already known to the astronomer--so, using a table of tangents, the angle denoted by A could be calculated. Since the instrument was symmetric, the angle between the directions of the stars was 2A.
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Telescope Increased viewing ability by magnifying light Able to see objects that are distant Able to see objects that are faint
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Position of Objects in Space
How can you accurately find and describe the position of an object in space? 1. How high in the sky is it? Altitude Horizon = 0 ° 90 ° = straight above you Zenith
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2. In which direction do you look?
Azimuth Compass direction (360° circle) Due north = 0° East = 90° South = 180° West = 270°
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Lab Activity 1: A Star’s Position
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8 4 2 3 7 5 1 6 Star ? ? Azimuth 75° 315° 285° 20° Altitude 5° 45° 80°
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Using Technology to Measure & Interpret Space
Suppose you are sending a probe to investigate Jupiter. How would you determine the distance to Jupiter to ensure that you have enough fuel? Triangulation and parallax are 2 ways of measuring distances indirectly
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Triangulation Measurement based on the geometry of a triangle
Can determine the distance to an object by measuring the angles between a baseline and the target
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How to measure 1. Measure off an accurate baseline 2. Select your object (opposite the baseline) 3. Stand at one endpoint & determine the inside angle between your sight line and the object 4. Repeat step 3 from the other endpoint 5. Make a scaled drawing 6. Mark a line perpendicular between the baseline and the object 7. Measure the scaled length of the perpendicular line & use scale to convert to real distance
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Examples Back wall = Earth Front wall = Jupiter Measure off baseline
Length = Target on Jupiter = Measure angles from each endpoint From endpoint A to target: From endpoint B to target:
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1 cm = 1 m
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What is the scale distance of the baseline?
What is the scale distance to the target? What is the real length of the baseline? What is the real distance to the target?
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1 cm = 10 AU 9 cm → 90 AU A B 13 cm → 130 AU
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1 cm = 5 light years 11.5 cm 57.5 light years 14.5 cm 72.5 light years
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How do you view an object from Earth from 2 different angles?
Parallax The apparent shift in position of object when it is viewed from 2 different places Astronomers use a star’s parallax to determine what angles to use when triangulating its position
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The longer the baseline, the more accurate the results
Longest baseline we can use from Earth is the diameter of Earth’s orbit
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Which are the best endpoints to use to determine the distance from Earth to the unknown star?
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Determining a Star’s Direction of Motion
Stars are not stationary How do we measure the distance to an object that is moving?
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Spectrum of Stars Way to visualize the different colors of light that are coming from a star Can break up the light coming from a star by passing it through a spectroscope Measures how much light is coming at each color
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The spectra often contain dark lines at particular colors
Means there is much less light coming from the star at that color Can use the information from these "spectral lines" to figure out what a star is made of Creates a fingerprint for individual stars
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Position of dark band in spectrum appear to shift as the star moves towards or away from Earth
Assume Earth is standing still
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Doppler Effect The apparent change in the frequency of a wave between an observer and a source as the source moves toward or away from the observer
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The Doppler Effect allows us to determine if stars are moving towards Earth or away from Earth and at what speed
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Star is moving toward Earth
Dark bands shift towards BLUE end of spectra Star is moving away from Earth Dark bands shift towards RED end of spectra Amount of shift = speed
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Spectrum Analysis
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hydrogen, oxygen, and aluminum
B) carbon, aluminum, and helium C) carbon, hydrogen, and oxygen D) oxygen and aluminum
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Blue light has a higher frequency than red light
Blue light has a higher frequency than red light. A Blue shift represents a celestial light source that is _____ Earth. A) moving away from B) moving beside C) rotating around D) moving towards
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