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Prentice Hall EARTH SCIENCE. Tarbuck Lutgens. . Using figure 3 on page 616 answer the following questions What is the main difference between these two models of the solar system? How do changing models of the solar system demonstrate the self-correcting nature of science?. STARTER.
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PrenticeHallEARTH SCIENCE TarbuckLutgens
Using figure 3 on page 616 answer the following questions What is the main difference between these two models of the solar system? How do changing models of the solar system demonstrate the self-correcting nature of science? STARTER
22.1 Early Astronomy Key Concepts How does the geocentric model of the solar system differ from the heliocentric model? What were the accomplishments of early astronomers? Vocabulary astronomy, geocentric, heliocentric, retrograde motion, ellipse, astronomical unit (AU)
Ancient Greeks 22.1 Early Astronomy Astronomy is the science that studies the universe. It includes the observation and interpretation of celestial bodies and phenomena. The Greeks used philosophical arguments to explain natural phenomena. The Greeks also used some observational data.
Astrolabe Early astronomers often used instruments called astrolabes to track the positions on the sun and stars.
Calculating Earth’s Circumference This diagram shows the orientation of the sun’s rays at Syene (Aswan) and Alexandria in Egypt on June 21 when Erastothenes calculted Earth’s circumfrence.
Ancient Greeks 22.1 Early Astronomy Geocentric Model • In the ancient Greeks’ geocentric model, the moon, sun, and the known planets—Mercury, Venus, Mars, and Jupiter—orbit Earth. Heliocentric Model • In the heliocentric model, Earth and the other planets orbit the sun.
Geocentric and Heliocentric Models A Heliocentric Model of the Universe A Geocentric Model of the Universe
Ancient Greeks 22.1 Early Astronomy Ptolemaic System • Ptolemy created a model of the universe that accounted for the movement of the planets. • Retrograde motion is the apparent westward motion of the planets with respect to the stars.
Retrograde Motion When viewed from Earth, Mars moves eastward among the stars each day. Then periodically it appears to stop and reverse direction. This apparent movement, called retrograde motion occurs because Earth has a faster orbital speed than Mars and overtakes it.
Reading Checkpoint What is retrograde motion??
The Birth of Modern Astronomy 22.1 Early Astronomy Nicolaus Copernicus • Copernicus concluded that Earth is a planet. He proposed a model of the solar system with the sun at the center.
The Birth of Modern Astronomy 22.1 Early Astronomy Tycho Brahe • Tycho Brahe designed and built instruments to measure the locations of the heavenly bodies. Brahe’s observations, especially of Mars, were far more precise than any made previously.
The Birth of Modern Astronomy 22.1 Early Astronomy Johannes Kepler • Kepler discovered three laws of planetary motion: 1. Orbits of the planets are elliptical. 2. Planets revolve around the sun at varying speed. 3. There is a proportional relationship between a planet’s orbital period and its distance to the sun.
The Birth of Modern Astronomy 22.1 Early Astronomy Johannes Kepler • An ellipseis an oval-shaped path. • An astronomical unit (AU)is the average distance between Earth and the sun; it is about 150 million kilometers.
Planet Revolution A line connecting a planet to the sun would move in such a manner that equal areas are swept out in equal times. Thus, planets revolve slower when they are farther from the sun and faster when they are closer.
The Birth of Modern Astronomy 22.1 Early Astronomy Galileo Galilei • Galileo’s most important contributions were his descriptions of the behavior of moving objects. • He developed his own telescope and made important discoveries: 1. Four satellites, or moons, orbit Jupiter. 2. Planets are circular disks, not just points of light. 3. Venus has phases just like the moon. 4. The moon’s surface is not smooth. 5. The sun has sunspots, or dark regions.
The Solar System Model Evolves In the Ptolemaic system, the orbit of Venus lies between the sun and Earth. In the Copernicus system, Venus orbits the sun and all its phases are visible from Earth As Galileo observed, Venus goes through phases similar to the moon.
The Birth of Modern Astronomy 22.1 Early Astronomy Sir Isaac Newton • Although others had theorized the existence of gravitational force, Newton was the first to formulate and test the law of universal gravitation. Universal Gravitation • Gravitational force decreases with distance. • The greater the mass of an object, the greater is its gravitational force.
Gravity’s Influence on Orbits Without the influence of gravity, planets would move in a straight line out into space.
Create three review questions with answers from section 22.1. Hold you paper up so I can come by and check off when you are finished. Review of 22.1
I built instruments called pointers to measure the location of heavenly bodies. I came up with the most precise location of Mars than had ever been made. Who am I?
I was the first to formulate and test the Law of Universal Gravitation. Who am I?
I determined that Earth is a planet, not the center of the universe. Who am I?
I invented the telescope and made other discoveries such as: Planets are circular disks Venus has phases like the moon The moon’s surface is not smooth The are dark regions called sunspots Who am I?
I came up with the three laws of planetary motion. Who am I?
I came up with the concept of retrograde motion, which is the apparent westward drift of planets. Who am I?
I was credited for determining the circumference of Earth. Who am I?
I determined that the Earth was round because it always cast a curved shadow when it passed between the sun and the moon. Who am I?
A. built instruments called pointers to measure the location of heavenly bodies B. Earth is a planet, not the center of the solar system C. credited for finding the circumference of the Earth D. formulated and tested the Law of Universal Gravitation E. concluded the Earth is round F. retrograde motion G. 3 laws of planetary motion H. telescope, sunspots, planets are circular disks, discovered the moon’s surface is not smooth
22.2 The Earth-Moon-Sun System Key Concepts In what ways does Earth move? What causes the phases of the moon? Why are eclipses relatively rare events? Vocabulary Rotation, revolution, precession, perihelion, aphelion, perigee, apogee, phases of the moon, solar eclipse, lunar eclipse
Motions of Earth 22.2 The Earth–Moon–Sun System The two main motions of Earth are rotation and revolution. Precession is a third and very slow motion of Earth’s axis.
Motions of Earth 22.2 The Earth–Moon–Sun System Rotation • Rotation is the turning, or spinning, of a body on its axis. • Two measurements for rotation: 1. Mean solar day is the time interval from one noon to the next, about 24 hours. 2. Sidereal day is the time it takes for Earth to make one complete rotation (360º) with respect to a star other than the sun—23 hours, 56 minutes, 4 seconds.
Motions of Earth 22.2 The Earth–Moon–Sun System Revolution • Revolution is the motion of a body, such as a planet or moon, along a path around some point in space. • Perihelion is the time in January when Earth is closest to the sun. • Aphelion is the time in July when Earth is farthest from the sun.
Motions of Earth 22.2 The Earth–Moon–Sun System Earth’s Axis and Seasons • The plane of the ecliptic is an imaginary plane that connects Earth’s orbit with the celestial sphere. • Because of the inclination of Earth’s axis to the plane of the ecliptic, Earth has its yearly cycle of seasons. Spring Equinox- March 20 or 21 Autumn Equinox- September 22 or 23 Summer Solstice- June 21 or 22 Winter Solstice- December 21 or 22
Motions of Earth 22.2 The Earth–Moon–Sun System Precession • Precession traces out a cone over a period of 26,000 years. Earth–Sun Motion • The solar system speeds in the direction of the star Vega. • The sun revolves around the galaxy. • Earth is presently approaching one of its nearest galactic neighbors, the Great Galaxy in Andromeda.
Reading Checkpoint What is precession?
Motions of the Earth–Moon System 22.2 The Earth–Moon–Sun System Perigee is the point at which the moon is closest to Earth. Apogee is the point at which the moon is farthest from Earth.
