AST 2010 Descriptive Astronomy Study Guide – Exam I Department of Physics and Astronomy Wayne State University 1

Introduction and overview Identify the most significant structures in the universe: Earth, planets, Sun, solar system, stars, galaxy, clusters and superclusters.. Understand the basics of the scientific method and scientific protocol Understand numbers in astronomy: astronomical units, powers of ten, MKS system, scientific notation

A first look at the Sky Identify the key objects populating the day and night sky.Describe how the Sun and stars move through the sky during day and night.Explain the notions of horizon and cardinal directions. Define the notions of constellation and asterism Recognize selected famous asterisms such as the Big Dipper, the Summer Triangle, and the Swan. Know basic facts about constellations

Cycles of the Sun and Planets Explain what is meant by Zodiac. Characterize the orbits of the planets Distinguish and explain the notions of opposition and conjunction in the context of the motion of planets in the solar system. Explain why transits and eclipses of the planets by the Sun (or the Moon) are very rare. AST 2010: Chapter 4 4

Shape of the Earth Describe the two observations and arguments used by the Greek philosopher Aristotle to establish that the Earth has the shape of a sphere Discuss few methods you could use to verify that the Earth is indeed round, i.e. approximately in the form of a sphere.

Mapping the Earth and the Celestial Sphere Describe the coordinate system commonly used by geographers to identify locations on the surface of the Earth. Explain, identify, and draw latitudes, longitudes, equator, and meridians on a terrestrial globe and on maps.Identify the location of the Prime Meridian, and explain its role in cartography.Identify the western, eastern, northern and southern hemispheres Explain the notion of projection used by geographers to draw maps of the earth. Find sites or locations of interest based on the latitude and longitude•Describe the altitude-azimuth coordinate system used by astronomers to measure the position of objects in the sky from a given location on Earth. Explain why astronomers have found it necessary to invent the celestial coordinate system.Describe the celestial coordinate system used by astronomers to express the position of objects on the celestial sphere. Find stars or other celestial objects on a celestial map based on their declination and right ascension.

The Apparent Motion of the Sun Describe the trajectory of the Sun in the sky throughout the day, and how it changes throughout the year; and more specifically it rises and sets, and how these positions evolve throughout the year as viewed from different locations on Earth. Explain the notion of ecliptic Explain the significance of the Arctic and Antarctic circles, and the tropic of Cancer and tropic of Capricorns. Discuss how the path of the Sun in the sky enabled ancient astronomers to predict the passage of the seasons.

Distance and Size of the Sun and Moon Explain how Aristarchus of Samos used the shadow of the Earth on the Moon during an eclipse to estimate the size of the Moon and its distance from Earth. Explain how he also determined the distance and size of the Sun Discuss the arguments set forth by Aristarchus and Aristotle in favor of heliocentric and geocentric views of the world.

Sizing the Earth Understand and discuss the method used by Eratosthenes to determine the diameter of the Earth.

Measuring the size of celestial bodies Explain how one can use similar triangles to measure the height or size of distance objects. Apply the basic proportionality between the sides of similar triangles to determine the size of distant objects.

The apparent motion of planets Explain the origin of the word "planet” Distinguish the planets based on their position in the sky, color, and brightness .Explain why Mercury and Venus can only been observed as evening or more "stars” Describe the model formulated by the ancient Greek EudoxusDescribe the regular and retrograde motions of planets in the sky. Describe in qualitative terms how Ptolemy explained observations of the retrograde motion of the planets. Explain the notions of deferent and epicycle. Distinguish and explain the difference between the geocentric and heliocentric models.

Copernicus, Tycho Brahe, Kepler, Galileo Understand what each individual major contributions are Understand the method(s) each of them used to arrive at the conclusions they published Understand the consequences of their discoveries

Lecture 1: Astronomical Motion: Inertia, Mass, and Force Lecture 2: Force, Acceleration, and Interaction Lecture 3: The Universal Law of Gravity Lecture 4: Measuring a Body’s Mass Using Orbital Motion AST 2010: Chapter 3

The Earth really moves! Stellar Parallax Foucault’s Pendulum AST 2010: Chapter 3

Lecture 1: Cycles of the Sun and Planets Explain what is meant by Zodiac. Characterize the orbits of the planets Distinguish and explain the notions of opposition and conjunction in the context of the motion of planets in the solar system. Explain why transits and eclipses of the planets by the Sun (or the Moon) are very rare. Explain what astronomers mean by obliquity. AST 2010: Chapter 4 15

Lecture 2: The Seasons Explain how the seasons are produced by the tilt of the Earth not by its eccentric orbit.Explain the significance of equinox and solstice. Explain how the seasons are defined. AST 2010: Pruneau: Version 1.0: Chapter 4: Lecture 2 16

Calendars Discuss in broad terms why and how our society has evolved to have a year composed of 12 months, and weeks of seven days. Contrast the western calendar with those based on the Muslim, Judaic, Chinese, and Mayan cultures. Identify and discuss the origins of the names given to weekdays and months. AST 2010: Chapter 4 17

Precession of the Earth Describe the notion of precession.Describe and characterize the precession of Earth’s rotation axis.Discuss the implications of the precession of Earth’s rotation axis relative to observations of celestial objects, the chronicling of time, and climate differences and changes. AST 2010: Chapter 4 18

Motion and Phases of the Moon, and eclipses Define and characterize the lunar month.Identify and describe the various phases of the Moon.Explain the various phases of the Moon in the context of the heliocentric model. Understand eclipses: how they happen and when they happen AST 2010: Chapter 4 19

AST 2010 Descriptive Astronomy Chapter 6Light and Telescopes The Nature of Light The Effect of Distance On Light The Nature of Matter The Chemical Elements Atomic Energies AST 2010: Chapter 6 20

The Colors of Visible Light White Light AST 2010 Descriptive Astronomy Chapter 6 Part 2: The Electromagnetic Spectrum The Colors of Visible Light White Light Infrared and Ultraviolet Radiation Energy Carried by Photons. Radio Waves High-Enrgy Radiation AST 2010: Chapter 6 21

AST 2010 Descriptive Astronomy Chapter 6 Part 3: Focusing Light Refracting Telescopes Reflecting Telescopes Reflectors vs Refractors Color Dispersion AST 2010: Chapter 6 22

Part 4: Telescope Resolution AST 2010 Descriptive Astronomy Chapter 6 Part 4: Telescope Resolution Resolution and Diffraction Calculating the Resolution of a Telescope Interferometers AST 2010: Chapter 6 23

Part 5: The Earth’s Atmosphere and Space Observatories AST 2010 Descriptive Astronomy Chapter 6 Part 5: The Earth’s Atmosphere and Space Observatories Atmospheric Absoprtion Atmospheric Refraction Observatories in Space Gamma Rays AST 2010: Chapter 6 24