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Chapter 22outline
 

Chapter 22outline

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    Chapter 22outline Chapter 22outline Presentation Transcript

    • Chapter 22 Origin of Modern Astronomy
    • Early Astronomy
      • Earth is just one of eight major planets and 3 dwarf planets that orbit our sun.
      • Our sun is just one of perhaps 100 billion stars that make up our galaxy the Milky Way.
      • The Milky Way is just one of billions of galaxies.
      • Where does this knowledge come from??????????
    • Ancient Greeks
      • ___________ is the science that studies the universe. Astronomy deals with the properties of objects in space and the laws under which the universe operates.
      • “Golden Age” of early astronomy (600 B.C. – A.D. 150) was centered in ___________.
    • Greeks developed
      • The basics of ___________ and ___________
      • Measured the distances of the sun and moon
      • Aristotle determined that the Earth was round because it cast a round shadow on the moon. This theory was later abandoned.
      • ___________ first to calculate the circumference of the Earth…..
      • Describe his experiment and figure his mistakes.
    • Here is how he did it……….
    • 7.2 0 7.2 0
    • Then he calculated How much of a circle is ___________ ? ___________ The total distance was? 39,400 km. The actual distance is closer to 40,075 km.
    • Problems with the solution……
      • 1.
      • 2.
      • 3.
      • 4.
      • ___________ developed star catalogue. He determined the locations of 850 stars, which de divided into six groups according to their brightness.
      • He measured the length of the year to within minutes
      • He developed a method of predicting the times of lunar eclipses to within a few hours.
    • ___________ Model
      • ___________ centered solar system… outside the solar system the stars traveled within a hollow sphere called the celestial sphere.
    • ___________ Model
      • ___________ centered
      • Aristarchus (312 – 230 B.C.) first to believe in this model.
      • This model was later proposed by Copernicus (1473 – 1543) and proved by his student Galileo.
      • This model was not accepted originally.
    • Ptolemaic System
      • An attempt to explain planetary movement referred to as ___________ .
      • Retrograde motion is the ___________ of a planet.
      • How is this possible?
    • ___________ :
      • Concluded that Earth was a planet.
      • He proposed a heliocentric solar system model.
    • v
      • Built an observatory near Copenhagen.
      • He developed and used several instruments made of stone to make calculations.
      • Brahe made precise observations about Mars . Later in life he found and assistant by the name of Johannes Kepler.
    • ___________
      • Discovered three ___________.
      • Astronomical unit – distance from the Earth to the sun or 150,000 kilometers
    • Three Laws of Planetary Motion
      • All orbits are ___________ in shape
      • An ___________ is an almost perfect circle
      • ___________ Law
      • Each of these triangles are equal in area
      • Can you understand the Earth travels faster as it gets closer to the sun and slower as it moves away from the sun?
      • ___________ Law
      • This law ___________ ( its year) of any planet.
      • The base unit of measure is the distance from the Earth to the sun which equals 1 astronomical unit or (approx. 150, 000,000 km.)
      • Solar distances can be calculated when the periods of revolution (orbit) are known.
    • T 2 =d 3
      • Ex. Using Mars
      • Mars revolution equals 1.88 years
      • The square of this is 3.54
      • The cube root of this is 1.52
      • This means that Mars is 1.52 a.u. from the sun.
    • Using the formula another way…
      • If you take the distance in a.u. and cube it.
      • Then take the square root of that number, you will calculate the period of revolution of the orbiting body.
      • Ex. Jupiter is approx. 5 a.u. from the sun
      # 3 then take square root 5 3 = 125 125 = 11.3 years
    • ___________
      • His most important contributions were his descriptions of the behavior of moving objects.
      • 1609 Galileo heard of a Danish lens maker who had devised a system of lenses that could magnify objects.
      • Without ever seeing a telescope Galileo constructed his own.
      • With the aid of his telescope Galileo discovered:
      • 1. Four satellites orbiting Jupiter. Today these moons are called Galiliean moons. This discovery proved that objects were orbiting another body besides the Earth.
      • 2. Planets are circular disks. It was believed they were only points of light.
      • 3. Venus has phases just like the moon.
      • 4. The moon’s surface was not smooth.
      • 5. The sun had spots.
    • ___________
      • Scientists of the time wondered about two points:
      • 1. What causes a moving object to continue to move.
      • 2. What force keeps the bodies in space from traveling in a straight line out into space.
      • Although others had theorized the existence of such a force, Newton was the first to formulate and test the law of universal gravitation.
      • According to Newton, every body in the universe attracts every other body with a force that is directly proportional to their masses and inversely proportional to the square of the distance between their centers of mass.
      • Example: The gravitational force decreases with distance, so that two objects 3 kilometers apart have 32, or 9, times less gravitational attraction than if the same objects were 1 kilometer apart.
      • The greater the mass of the object, the greater is its gravitational force.
      • (discuss the difference between mass and weight)
      • ___________ being the total amount of matter an object contains.
      • ___________ is the force of gravity upon an object.
      • Earth moves forward in its orbit about 30 kilometers per second.
      • During the same second, the force of gravity pulls it towards the sun about 0.5 centimeters.
      • Newton concluded that it is the combination of Earth’s forward motion and its “falling” motion that defines its orbit.
    • Newton’s laws of Gravity
      • An ___________ (force) in motion will stay in motion until another ___________ (force) acts upon it.
      • The larger the mass, means that it will have stronger gravity . (used to calculate escape velocities)
      • For every action there is an ___________ & ___________ reaction
    • The Earth-Moon-Sun System
      • Stonehenge……. Lets take a look
    • Motions of Earth
      • The two main motions of Earth are ___________ (spin) and ___________ (orbit) .
    • Revolution is ……..
      • is the motion of a body, such as a planet or moon, along a path around some point in space.
      • Earth’s average speed is 107,000 kilometers per hour.
      • Our average distance from the sun is 150,000,000 kilometers. However, all orbits are elliptical so….
      • Earth’s ___________ is when the Earth is closest to the sun about 147,000,000 kilometers. This occurs on January 3rd each year.
      • Earth’s ___________ is when Earth is at is farthest point from the sun about 152,000,000 kilometers. This occurs on July 4th each year.
      • Is this why we have seasons????????
      • The apparent annual path of the sun against the backdrop of the celestial sphere is called the ___________.
      • The planets and moon travel along the same plane as Earth, so their paths on the ___________ lie near the ecliptic.
    •  
    • Earth’s axis ……
      • is tilted on this plane ___________ to the ecliptic.
      • This tilt creates ___________.
      • When the apparent position of the sun is plotted on the celestial sphere over a period of a year’s time, its path intersects the celestial equator at two points.
      • These intersect points are spring (March 20 or 21) and fall (Sept. 22 or 23).
      • When the sun is 23.5 0 north of the equator…..
      • ___________ occurs.
      • When the sun is 23.5 0 south of the equator…..
      • ___________ occurs.
    • Procession
      • The Earth has another very slow motion called procession, which is a slight movement, over 26,000 years.
      • The Earth’s axis traces a circle in space similar to the wobble of a spinning top.
      • At the present time the northern axis points to Polaris, which is referred to as the North Star.
      • In the year 14,000 our northern axis will point to Vega, which will then become our north star.
      • Then in the year 28,000 Polaris will again be our north star.
    •  
    • Rotation …….
      • Rotation results in day and night.
      • It has become a standard of measuring time.
      • Each rotation equals about 24 hours.
      • Notice that it says about 24 hours!
      • ___________ is the time it takes for the Earth to make one complete rotation (360 degrees) with respect to a star other than our sun.
      • A sidereal day is equal to ___________ hours ___________ minutes and ___________ seconds .
    •  
      • ___________ is good for determining time.
      • Sidereal is used to determine the ___________ Earth is to be at the beginning of each season.
    • Earth-Sun Motion
      • The Earth, sun, and the rest of the solar system travel through space at a speed of 20 kilometers per second towards the star, Vega.
      • Our solar system also revolves around the galaxy.
      • The trip takes 230 million years and travels at speeds approaching 250 kilometers per second.
      • Galaxies are also in motion.
      • Earth is presently approaching the Great Galaxy in Andromeda.
    • Motions of the Earth-Moon System
      • Average distance to the moon is 384,401 kilometers.
      • ___________ (farthest point in its orbit) and ___________(closest point in its orbit).
      • Lunar phases are a result of the motion of the moon and the sunlight that is reflected from its surface.
    • Lunar Motions
      • The moon cycle of phases takes ___________ days .
      • One orbit of the moon around the earth takes ___________ days
      • One rotation on the moon takes ___________ days
      • Something doesn’t seem to add up!!!!!!!!!!!!!
      • What does this all mean????
      • If the orbit and rotation of the moon are the same (27.3 days), that means?
      • ___________
      • Why then does it take the moon longer to go through its phases?
      • It must “___________” to where the ___________ to be since the Earth is orbiting the sun.
    • Because the moon must catch up to the Earth each day, it rises 50 minutes later each night .
    • Phases of the Moon
      • Phases result from the motion of the moon and the sunlight that is reflected.
      • For the purposes of this class we will only use the following phases:
      • ___________ - dark
      • ___________ – lighted side grows larger
      • ___________
      • ___________ – shadowed side grows larger
    •  
    • Eclipses
      • Two types:
      • ________
      • ________
    •  
      • ________ occur with new moon phase
      • ________ occur with full moon .
      • During a new-moon or full moon phase, the moon’s orbit must cross the plane of the ecliptic for an eclipse to occur.
      • There are usually ________ that occur in two sets. One lunar and then a solar, then 6 months later another lunar and solar.
      • During any given year there are not more than ________ eclipses.
      • Solar eclipses last about 7 minutes in any given area.
      • The size of the shadow is approximately 275 kilometers wide or about the size of South Carolina. (FYI)
      • The next total solar eclipse will occur August 21, 2017.
    • Earth’s Moon
      • Moon characteristics:
      • Size 3475 kms. Or about ________ that of Earth
      • 6 Apollo missions landed on the moon between 1969 and 1972
      • Moon’s density is 3.3 which is less than the 5.5 of Earth rocks.
      • Gravity is ________ of Earth
    • Lunar Surface
      • No volcanism
      • ________ – most craters were produced by the impact of rapidly moving debris.
      • A meteoroid 3 meters in diameter can make a crater 150 meters wide.
      • Larger craters like Kepler and Copernicus were formed with the impact of bodies 1 kilometer or more in diameter.
      • ________ – debris splash marks near the crater.
    •  
    •  
    •  
    • Rays with craters
      • ________ – or mountain peaks.
      • The highest is near 8 kilometers in height or just 1 kilometer short of Mt. Everest.
    • ________ – (seas) name by Galileo
      • Relatively dark smooth areas on the moon’s surface.
      • Maria formed from ancient beds of basaltic lava, originated when asteroids punctured the lunar surface, letting magma bleed out.
      • These lava flows are often 30 meters thick.
      • Long channels called ________ are associated with maria. They may be the remains of ancient lava flows or lava tunnels then caved in.
    •  
      • ________ – lunar regolith, which is a soil like layer on the moon. It is composed of igneous rocks, glass beads, and fine lunar dust.
    •  
    • Lunar History
      • Most accepted lunar formation model:
      • The origin of the moon occurred when the solar system was forming, a body the size of Mars impacted the Earth.
      • A portion of the liquefied material entered Earth’s orbit where it combined to form the moon.
    • Evidence
      • 1. Ejected material would have been iron poor and so is the moon.
      • 2. The ejected material would have stayed in orbit long enough to loose its water.
    •  
      • The moon evolved in three stages:
      • The original crust meaning ________
      • maria basins
      • rayed craters
      • Continued impact of meteoroids combined with radioactive decayed materials, generated enough heat to melt the moon’s outer shell and possibly the inner as well.
      • The highland areas are estimated to be 4.5 billion years old.
      • The maria basins are younger than the highlands and in some places over lap some highland areas.
      • The last features to form were the rayed craters.
      • Most of the old craters are ray-less .