# [04] Seasons, Phases, and Eclipses (9/7/17)

Size: px
Start display at page:

Transcription

1 1 [04] Seasons, Phases, and Eclipses (9/7/17) Upcoming Items Homework #2 due next lecture. Read Ch. 3.3 and do the self-study quizzes for next lecture, and skim 2.4, 3.1, 3.2, &

2 2 LEARNING GOALS Chapters For this class, you should be able to predict seasonal changes based on a planet s tilt and orbit, and explain the contributing factors; identify a planet or moon's phase, and/or when it will be visible from your location, given its position relative to you and the Sun, and vice versa; describe the conditions needed for each type of eclipse to occur and explain why we do not see one involving the Moon each month.

3 3 PRACTICE ClassAction: Coordinates & Motions G2: Change to Earth Seasons G3: Season Contributor(s) G4: No Orbital Tilt G12: Sun s Rays G13: Sun Movement G14: Sun at Zenith Frequency G15: Effects of Tilt G30: Sun Rise/Set After Equinox C3: Sun Paths 1 C4: Sun Paths 2 D2: Seasons on Uranus

4 4 Which of the following does not change over the course of the Earth s orbit? A. The number of daylight hours in College Park. B. The angle at which sunlight hits the Earth s surface. C. The amount of the northern hemisphere that is illuminated. D. The amount of the Earth that is illuminated.

5 5 Which of the following changes the least over the course of a year? A. The number of daylight hours in College Park. B. The number of daylight hours in Equatorial Guinea. C. The number of daylight hours in Iceland. D. They all change the same amount. E. It s impossible to tell.

6 6 I (North tilted away) II NORTH III IV Sunlight (South tilted away) SOUTH Figures I IV show the Earth at four points in its orbit, each representing a different season. Arrange them in order of the year, starting with winter in the Northern hemisphere. A. III, I, IV, II. B. III, II, IV, I. C. IV, II, III, I. D. IV, I, III, II. E. More than one arrangement is possible.

7 7 PRACTICE ClassAction: Lunar Cycles G1: Identify Phase from Picture G3: Identify Lunar Position from Phase G5: Phases, Eclipses and Tides G6: Phase Evolution G8: Rising/Meridian/Setting Times G10: Types of Lunar Eclipses G13: Horizon Diagram: Identify Phase G14: Horizon Diagram: Identify Time C3: Earthrise on the Moon C4: Location of the Crescent Moon C7: Phases Visible

8 8 During a new moon, how much of the Moon s surface is illuminated by the Sun? A. None of it. B. A quarter of it. C. Half of it. D. All of it.

9 9 View looking down on North Pole DFS A B Sunlight Earth C D You look at the sky one night and see the Moon as it is shown in the figure. Which letter corresponds to the Moon s position relative to Earth? Answer: D

10 10 DFS (A) Moon FS (B) Sunlight DFS (C) Earth FS (D) View looking down on North Pole For the given position of the Moon relative to the Earth and Sun, what phase of the Moon would you see? Answer: B

11 11 Imagine that the Sun increased in size, and we are somehow still alive to observe it. It is big enough that the Moon can no longer fully eclipse it. Which of the following would compensate for the Sun s growth, leaving us able to see a total solar eclipse? I. Decrease the size of the Earth. II. Increase the size of the Moon. III. IV. A. II only. B. II, IV. C. II, III, IV. Further increase the size of the Sun. Increase the distance between the Earth and the Sun. V. Increase the distance between the Earth and the Moon. D. I, II, IV, V. E. III only.

12 The Seasons 12

13 13 Cause of Seasons Could changing distance of the Earth to the Sun explain the seasons by itself? That is, the Earth s orbit is not perfectly circular. When it is closer to the Sun, it gets a larger flux of radiation from the Sun; when it is farther away, it gets a smaller flux. Can that, by itself, produce the seasons?

14 14 Cause of Seasons Could changing distance of the Earth to the Sun explain the seasons by itself? That is, the Earth s orbit is not perfectly circular. When it is closer to the Sun, it gets a larger flux of radiation from the Sun; when it is farther away, it gets a smaller flux. Can that, by itself, produce the seasons? NO! If distance were all that mattered, we ve have identical seasons to Australia, and we don t. Something else has to play a role; in this class we ll quantify what that is.

15 15 Tilt! The basic idea Earth s axis tilted wrt orbit Over a year, angle of Sun s rays changes Thus the flux of energy on the Earth s surface changes This can change the average temperature on Earth over the year, and we can do a demo to show that the maximum flux will be different for the northern and southern hemisphere, which is what we observe. But still, distance has to matter at least a little, right? So we need to quantify which effect is more important.

16 16 Getting Rid of a Misconception General comment: we are not blank slates ; instead, when we hear new information, we try to fit it into what we previously thought we knew. If what we originally thought was wrong, this can cause problems! In this case: some people think distance is the key. When they hear about tilt, they try to fit this into their previous view by believing that the main effect of tilt is that the part of the Earth tilted toward the Sun is closer to the Sun. Technically, yes! But the Earth s size is only about 1/20,000 of the Earth-Sun distance, so the difference is completely negligible.

17 17 The Central Role of Flux Anticipating a bit a discussion we ll have later in the semester... Other things being equal (note the caveat!), the average amount of radiation, per time, per area on Earth s surface where you are, is the most important quantity. This is called the flux. Thus we need to figure out the effect on the flux of (1) the changing distance of the Earth from the Sun, and (2) the tilt of the Earth s axis to the Earth s orbit, and compare the two to determine which is more important. This will also allow us to judge whether distance or tilt is more important on other planets!

18 18 Inverse Square Law for Light Suppose you have light coming out from a source (for example, the Sun!) As you go farther, the same amount of light is distributed over a larger area. Area of a sphere is 4πr 2 Thus light per area scales as 1/r 2 In a circular orbit, there is a constant distance, so no change In a very elliptical orbit, the change can be large From Wikipedia

19 19 What Does Tilt Actually Do? Take a sphere and hold it up to a distant light source. Even though the rays are all parallel to each other, they are distributed over a much larger area near the pole than near the equator. If the rays are tangent to the surface, the flux goes to zero! Can you see why? The Earth s rotation axis is tilted by 23.5 degrees relative to its orbit We ll work out what this means! /earthtilt_ d7be0b28f32ff16ca188865c.jpg?

20 20 Effect of Changing Distance We ll do some group questions to figure out the relative contribution of changing distance, versus Earth s tilt. We ll start with distance. At its farthest, Earth is 3.4% farther from the Sun than it is at its closest. In your groups: use the inverse square law to calculate how much the flux changes just due to the changing distance. Here how much would be in percent; that is, how many percent greater is the flux at the closest distance, compared with the flux at the farthest distance?

21 21 Effect of Tilt, Part 1 Suppose we have parallel rays incident on a sphere: q θ Group question: How does the area over which a bundle of rays is spread depend on θ? Note: the area has to go up for θ farther away from the equator. What should be the answer in the limit that θ=90 degrees?

22 22 Effect of Tilt, Part 2 Earth s axis is tilted relative to its orbit by 23.5 degrees. Thus as the Earth moves around the Sun, a given point on the Earth s surface presents different angles to the Sun s rays. Group Q: given that College Park is at 39 degrees latitude, what is the smallest angle it presents, at noon, to the Sun s rays? The largest? Finally: what does that imply about the flux variation due to tilt alone? Compare that with the distance effect.

23 23 How do we mark the progression of the seasons? We define 4 special points: A. Spring/vernal (March) equinox B. Summer (June) solstice C. Fall/autumnal (September) equinox D. Winter (December) solstice

24 24 Solstices and equinoxes recognized by Sun s path: Summer solstice: highest path, rise and set at most extreme north of due east. Winter solstice: lowest path, rise and set at most extreme south of due east. Equinoxes: Sun rises precisely due east and sets precisely due west.

25 25 Seasonal changes are more extreme at high latitudes Path of the Sun on the summer solstice at the Arctic Circle. Group Q: do same calculation as for College Park, but at 61 degrees north latitude (latitude of Anchorage, Alaska)

26 26 How does the orientation of Earth s axis change with time? Although the axis seems fixed on human time scales, it actually precesses over about 26,000 years.! Polaris won t always be the North Star!! Positions of equinoxes/solstices move. Earth s axis precesses like the axis of a spinning top.

27

28

29 29 Why do we see phases of the Moon? Half the Moon illuminated by Sun and half dark, always. We see a changing combination of the bright and dark faces as the Moon orbits.

30 30 Moon Phases: 29½-day Cycle } Moon visible in afternoon/evening. Gets fuller and rises later each day. } Moon visible in late night/morning. Gets less and sets later each day.

31 31 Thought Question It s 9 am. You look up in the sky and see a moon with half its face bright and half dark. What phase is it? A. First quarter. B. Waxing gibbous. C. Third quarter. D. Half moon.

32 32 Thought Question It s 9 am. You look up in the sky and see a moon with half its face bright and half dark. What phase is it? A. First quarter. B. Waxing gibbous. C. Third quarter. D. Half moon. Also called last quarter.

33 33 We see only one side of the Moon. Synchronous rotation: the Moon rotates exactly once with each orbit. This is why only one side is visible from Earth.

34 34 What causes eclipses? The Earth and Moon cast shadows. When either passes through the other s shadow, we have an eclipse.

35 35 When can eclipses occur? Lunar eclipses can occur only at full moon. Lunar eclipses can be penumbral, partial, or total. The next total lunar eclipse will occur Jan 20/21, 2019, and will be visible from College Park.

36

37 37 When can eclipses occur? Solar eclipses can occur only at new moon. Solar eclipses can be partial, total, or annular. There was a total solar eclipse on Aug 21, 2017, visible across much of the United States!

38

39 39 Why don t we have an eclipse at every new and full moon? The Moon s orbit is tilted 5 to ecliptic plane So we have about two eclipse seasons each year, with a lunar eclipse at full moon and solar eclipse at new moon.

40 Another look 40

41 41 Summary: Two conditions must be met to have an eclipse 1. It must be full moon (for a lunar eclipse) or new moon (for a solar eclipse). AND 2. The Moon must be at or near one of the two points in its orbit where it crosses the ecliptic plane (its nodes).

42 42 LG Seasons, Phases, and Eclipses We have seasons because of Earth s tilt, which causes there to be more direct light for longer during summer. The phase of the Moon depends on the Moon-Earth-Sun angle, which also determines the rise/transit/set time. A lunar eclipse can occur when the Earth is between the Moon and the Sun. A solar eclipse can occur when the Moon is between the Earth and the Sun. Eclipses involving Earth s Moon occur only twice a year due to the Moon s orbital inclination to the ecliptic. Other bodies in the solar system can experience seasons, phases, and eclipses for the same reasons as us.

43 43 Next Time: The Great Debate! Will divide class into thirds: one third will argue for heliocentric model, one third for geocentric model, one third will judge. Will alternate brief points between sides until done. Ground rules are that no observations past the time of Copernicus can be used (thus, for example, no telescopic observations are allowed) Just for fun! Point will be to see that determination of better model is not easy.

### 2.2 The Reason for Seasons

2.2 The Reason for Seasons Our goals for learning: What causes the seasons? How does the orientation of Earth's axis change with time? Thought Question TRUE OR FALSE? Earth is closer to the Sun in summer

### Chapter 2 Discovering the Universe for Yourself

Chapter 2 Discovering the Universe for Yourself 2.1 Patterns in the Night Sky Our goals for learning: What does the universe look like from Earth? Why do stars rise and set? Why do the constellations we

### Chapter 2 Discovering the Universe for Yourself. What does the universe look like from Earth? Constellations. 2.1 Patterns in the Night Sky

Chapter 2 Discovering the Universe for Yourself 2.1 Patterns in the Night Sky Our goals for learning: What does the universe look like from Earth? Why do stars rise and set? Why do the constellations we

### Chapter 2 Lecture. The Cosmic Perspective Seventh Edition. Discovering the Universe for Yourself Pearson Education, Inc.

Chapter 2 Lecture The Cosmic Perspective Seventh Edition Discovering the Universe for Yourself Discovering the Universe for Yourself 2.1 Patterns in the Night Sky Our goals for learning: What does the

### Chapter 2 Discovering the Universe for Yourself. Copyright 2012 Pearson Education, Inc.

Chapter 2 Discovering the Universe for Yourself 1 2.1 Patterns in the Night Sky Our goals for learning: What does the universe look like from Earth? Why do stars rise and set? Why do the constellations

### Chapter 2 Discovering the Universe for Yourself

Chapter 2 Discovering the Universe for Yourself 2.1 Patterns in the Night Sky Our goals for learning: What does the universe look like from Earth? Why do stars rise and set? Why do the constellations we

### Observing the Universe for Yourself

Observing the Universe for Yourself Figure 6-20 Solar-System Formation What does the universe look like from Earth? With the naked eye, we can see more than 2,000 stars as well as the Milky Way. A constellation

### 2.1 Patterns in the Night Sky

2.1 Patterns in the Night Sky Our goals for learning: What are constellations? How do we locate objects in the sky? Why do stars rise and set? Why don t we see the same constellations throughout the year?

### The Cause of the Seasons

The Cause of the Seasons Summer Winter Seasons are caused by the Earth s axis tilt, not the distance from the Earth to the Sun! Axis tilt changes directness of sunlight during the year. Why Does Flux Sunlight

### The celestial sphere, the coordinates system, seasons, phases of the moon and eclipses. Chapters 2 and S1

The celestial sphere, the coordinates system, seasons, phases of the moon and eclipses Chapters 2 and S1 The celestial sphere and the coordinates system Chapter S1 How to find our way in the sky? Let s

### Dive into Saturn.

Dive into Saturn http://www.pbs.org/wgbh/nova/space/death-dive-to-saturn.html Read Ch. 3 By next class time Do practice online quiz 01 Axis tilt changes directness of sunlight during the year. Why Does

### Today. Tropics & Arctics Precession Phases of the Moon Eclipses. Ancient Astronomy. Lunar, Solar FIRST HOMEWORK DUE NEXT TIME

Today Tropics & Arctics Precession Phases of the Moon Eclipses Lunar, Solar Ancient Astronomy FIRST HOMEWORK DUE NEXT TIME Tropic: Latitude where the sun [just] reaches the zenith at noon on the summer

### Chapter 2 Lecture. The Cosmic Perspective Seventh Edition. Discovering the Universe for Yourself

Chapter 2 Lecture The Cosmic Perspective Seventh Edition Discovering the Universe for Yourself Discovering the Universe for Yourself 2.1 Patterns in the Night Sky Our goals for learning: What does the

### The Ecliptic on the Celestial. Sphere. The Celestial Sphere. Astronomy 210. Section 1 MWF Astronomy Building. celestial equator are not

Astronomy 210 Section 1 MWF 1500-1550 134 Astronomy Building This Class (Lecture 3): Lunar Phases Check Planetarium Schedule Next Class: HW1 Due Friday! Early Cosmology Music: We only Come out at Night

### Chapter 1 Image Slides. Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Chapter 1 Image Slides Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. CH. 1: CYCLES OF THE SKY CO a 1.1 The Celestial Sphere CO b The nearest star to us is about

### The Celestial Sphere. Chapter 1. Constellations. Models and Science. Constellations. Diurnal vs. Annular Motion 9/16/2010

The Celestial Sphere Chapter 1 Cycles of the Sky Vast distances to stars prevent us from sensing their true 3-D arrangement Naked eye observations treat all stars at the same distance, on a giant celestial

Academic Year 2017-2018 Second Term Science Revision Sheet Grade 6 Name: Grade Date: Section: Part A. Science Practice. Circle the letter of your answer. 1. When the moon is waxing, its lighted part appears

### Today. Solstices & Equinoxes Precession Phases of the Moon Eclipses. Ancient Astronomy. Lunar, Solar FIRST HOMEWORK DUE NEXT TIME

Today Solstices & Equinoxes Precession Phases of the Moon Eclipses Lunar, Solar Ancient Astronomy FIRST HOMEWORK DUE NEXT TIME Tropic: Latitude where the sun [just] reaches the zenith at noon on the summer

### Name: Date: 5. The bright stars Vega, Deneb, and Altair form A) the summer triangle. B) the winter triangle. C) the Big Dipper. D) Orion, the Hunter.

Name: Date: 1. If there are about 6000 stars in the entire sky that can be seen by the unaided human eye, about how many stars would be seen at a particular instant on a given dark night from a single

### Astronomy 115 Section 4 Week 2. Adam Fries SF State

Astronomy 115 Section 4 Week 2 Adam Fries SF State afries@sfsu.edu Important Notes: Homework #1 is Due at the beginning of class next time. Attendance Sheet is going around one last time! Homework Questions?

### Today FIRST HOMEWORK DUE NEXT TIME. Phases of the Moon. Eclipses. Lunar, Solar. Ancient Astronomy

Today FIRST HOMEWORK DUE NEXT TIME Phases of the Moon Eclipses Lunar, Solar Ancient Astronomy Tropic: Latitude where the sun [just] reaches the zenith at noon on the summer solstice Arctic/Antarctic Circle:

### Name: Exam 1, 9/30/05

Multiple Choice: Select the choice that best answers each question. Write your choice in the blank next to each number. (2 points each) 1. At the North Pole in mid-november, the sun rises at a. North of

### Appearance of the Sky Orientation Motion of sky Seasons Precession (?)

Today Appearance of the Sky Orientation Motion of sky Seasons Precession (?) The Celestial Sphere Stars at different distances all appear to lie on the celestial sphere. The ecliptic is the Sun s apparent

### Motions of the Earth

Motions of the Earth Our goals for learning: What are the main motions of the Earth in space? How do we see these motions on the ground? How does it affect our lives? How does the orientation of Earth's

### Discovering the Universe for Yourself

Constellations: region in the sky with well defined borders; the familiar patterns of stars merely help us locate these constellations. 88 names were chosen by the International Astronomical Union. Every

### 3) During retrograde motion a planet appears to be A) dimmer than usual. B) the same brightness as usual C) brighter than usual.

Descriptive Astronomy (ASTR 108) Exam 1 B February 17, 2010 Name: In each of the following multiple choice questions, select the best possible answer. In the line on the scan sheet corresponding to the

### 1) Kepler's third law allows us to find the average distance to a planet from observing its period of rotation on its axis.

Descriptive Astronomy (ASTR 108) Exam 1 A February 17, 2010 Name: In each of the following multiple choice questions, select the best possible answer. In the line on the scan sheet corresponding to the

### CHAPTER 2 Strand 1: Structure and Motion within the Solar System

CHAPTER 2 Strand 1: Structure and Motion within the Solar System Chapter Outline 2.1 EARTH, MOON, AND SUN SYSTEM (6.1.1) 2.2 GRAVITY AND INERTIA (6.1.2) 2.3 SCALE OF SOLAR SYSTEM (6.1.3) 2.4 REFERENCES

### Motion of the Sun. motion relative to the horizon. rises in the east, sets in the west on a daily basis. Basis for the unit of time, the DAY

Motion of the Sun motion relative to the horizon rises in the east, sets in the west on a daily basis Basis for the unit of time, the DAY noon: highest point of Sun in sky relative to the horizon 1 altitude:

### Name: Earth and Space Assessment Study Guide. Assessment Date : Term Rotation Revolution

Name: Earth and Space Assessment Study Guide Assessment Date : Earth s Rotation and Revolution Term Rotation Revolution Brief Definition Earth s Time to Complete One complete spin on an axis 24 hours (or

### Appearance of the Sky Orientation Motion of sky Seasons Precession (?)

Today Appearance of the Sky Orientation Motion of sky Seasons Precession (?) The Celestial Sphere Stars at different distances all appear to lie on the celestial sphere. The ecliptic is the Sun s apparent

### Practice Seasons Moon Quiz

1. Which diagram represents the tilt of Earth's axis relative to the Sun's rays on December 15? A) B) C) D) 2. The diagram below represents Earth in space on the first day of a season. 5. Base your answer

### Seasons. What causes the seasons?

Questions: Seasons What causes the seasons? How do we mark the progression of the seasons? What is the seasonal motion of the sun in the sky? What could cause the seasonal motion of the sun to change over

### Before you Sit. Please Pick-up: Blue Information Sheet for Evening Observing. 1 Red and 1 Blue ticket for Observing/ Planetarium

Before you Sit Please Pick-up: Blue Information Sheet for Evening Observing. 1 Red and 1 Blue ticket for Observing/ Planetarium Evening Observing Observing at the Brooks Observatory: Three different weeks

### Day, Night, Year, and Seasons

Welcome Astronomers to the Sun, Moon, and Earth! The relationship between the Sun, Moon, and Earth is very important to the existence of life on Earth. Our quest is to find out how their relationships

### The Sun-Earth-Moon System

Name The Sun-Earth-Moon System Section 28.3 The Sun-Earth-Moon System Date Main Idea Details Read the title of Section 3. List three things that might be discussed in this section. 1. 2. 3. Review Vocabulary

### TAKEN FROM HORIZONS 7TH EDITION CHAPTER 3 TUTORIAL QUIZ

TAKEN FROM HORIZONS 7TH EDITION CHAPTER 3 TUTORIAL QUIZ 1. When Neap tides are occurring, a. a person experiences the lowest tides close to sunset and sunrise. b. the Sun and the Moon are separated by

### Astronomy 11. No, this course isn t all about Star Wars

Astronomy 11 No, this course isn t all about Star Wars Earth s Rotation How fast are people on the equator moving? s=d/t =circumference/24 hours =(40,000 km)/24 hours =1670 km/h That s Mach 1.4! What

### Eclipses September 12th, 2013

Eclipses September 12th, 2013 Who was the favorite Star Wars character of the class? A) Obi-Wan B) Jar Jar C) Luke Skywalker D) Yoda News! Dark matter http://mcdonaldobservatory.org/news/releases/2013/09/10

ASTR1010 Lecture 5 29 Jan 13 Today How the Sky Works: Stars, Seasons, Phases Announcements: Old-Fashioned Homework 1 released tonight on D2L, due ON PAPER next Tuesday at the start of class If you brought

### The Moon -Around the Earth and in the Sky

The Moon -Around the Earth and in the Sky Our goals for learning: Why do we see phases of the Moon? When do we see the phases of the Moon? What causes eclipses? Why do we see phases of the Moon? Lunar

### Welcome back. Scale. Week 2 Updates. PHYS 1302 Astronomy of the Solar System

Week 2 Updates Two in-class quizzes now completed Introductions List-serve Quick review of Chapter 1 Discuss Chapter 2 Chapter 3 next week (9/9). Welcome back Week 2 of PHYS 1302 Como se dice The h Syllabus:

### CHAPTER 2 A USER'S GUIDE TO THE SKY

CHAPTER 2 A USER'S GUIDE TO THE SKY MULTIPLE CHOICE 1. In one way of naming stars, a letter indicates its brightness relative to the other stars in the constellation. a. English b. Arabic c. Greek d. Cyrillic

### Seasons Motions of the Sun

ASTR1010 Lecture 6 31 Jan 13 Today How the Sky Works: Phases, Eclipses, Precession, Planets Announcements: Exam 1 Review sheets available up front Old-Fashioned Homework 1 emailed, due ON PAPER Tues SkyGazer

### Earth in Space. The Sun-Earth-Moon System

in Space The --Moon System What do you think? Read the two statements below and decide whether you agree or disagree with them. Place an A in the Before column if you agree with the statement or a D if

### November 20, NOTES ES Rotation, Rev, Tilt.notebook. vertically. night. night. counterclockwise. counterclockwise. East. Foucault.

NOTES ES, Rev,.notebook, and Rotates on an imaginary axis that runs from the to the South North Pole Pole vertically North The of the axis points to a point in space near day Pole Polaris night Responsible

### Practice Questions: Seasons #1

1. Seasonal changes on Earth are primarily caused by the A) parallelism of the Sun's axis as the Sun revolves around Earth B) changes in distance between Earth and the Sun C) elliptical shape of Earth's

### b. So at 12:00 p.m., are the shadows pointing in the direction you predicted? If they are not, you must explain this observation.

Astronomy 100 Name(s): Exercise 2: Timekeeping and astronomy The following exercise illustrates some basic ideas about time, and how our position in the solar system uniquely configures the measurement

### Day, Night & the Seasons. Lecture 2 1/21/2014

Day, Night & the Seasons Lecture 2 1/21/2014 Logistics The following students see me after class: A. Gonzalez, Chen Anyone who was not here on first day see me after class Pin Numbers - if you have not

### Earth is rotating on its own axis

Earth is rotating on its own axis 1 rotation every day (24 hours) Earth is rotating counterclockwise if you are looking at its North pole from other space. Earth is rotating clockwise if you are looking

### Chapter 1: Discovering the Night Sky. The sky is divided into 88 unequal areas that we call constellations.

Chapter 1: Discovering the Night Sky Constellations: Recognizable patterns of the brighter stars that have been derived from ancient legends. Different cultures have associated the patterns with their

### The. Astronomy is full of cycles. Like the day, the month, & the year In this section we will try to understand these cycles.

Understanding The Sky Astronomy is full of cycles Like the day, the month, & the year In this section we will try to understand these cycles. For Example Why do we think of stars as nighttime objects?

### Announcements. Homework 1 posted on Compass

Announcements Homework 1 posted on Compass Ordinarily due by classtime next Friday Jan 27, but HW1 available on Compass until Jan 30 can submit answers for score more than once: persistence pays off! Register

### S CIENCE O VERVIEW. 59 Lesson Plan. Standards Benchmarks. Science Overview. Lesson Overview. Answer Key. Resources. My Angle on Cooling ME S S EN G ER

S CIENCE O VERVIEW There are many different ways to cope with being in the presence of a hot object. A familiar one is to move away from it so that you do not feel its heat as strongly. Another is to change

### PHYS 160 Astronomy Test #1 Fall 2017 Version B

PHYS 160 Astronomy Test #1 Fall 2017 Version B 1 I. True/False (1 point each) Circle the T if the statement is true, or F if the statement is false on your answer sheet. 1. An object has the same weight,

### Orbital Mechanics. CTLA Earth & Environmental Science

Orbital Mechanics CTLA Earth & Environmental Science The Earth Spherical body that is flattened near the poles due to centrifugal force (rotation of the Earth) 40,074 KM across at the Equator 40,0007 KM

### Time, coordinates and how the Sun and Moon move in the sky

Time, coordinates and how the Sun and Moon move in the sky Using the colors and magnitudes of quasars drawn from the SDSS Catalog Archive Server to distinguish quasars from stars using the light they emit

### Physical Science. Chapter 22 The Earth in Space

Physical Science Chapter 22 The Earth in Space Earth s Rotation Axis imaginary line passing through the North and South Pole Earth s axis is tilted at 23 ½ degrees Rotation: the Earth spinning on its axis

### Astronomy 122 Section 1 TR Outline. The Earth is Rotating. Question Digital Computer Laboratory

Astronomy 122 Section 1 TR 1300-1350 Outline 1320 Digital Computer Laboratory Leslie Looney Phone: 244-3615 Email: lwlw@wuiucw. wedu Office: Astro Building #218 Office Hours: T 10:30-11:30 a.m. or by appointment

### Summary Sheet #1 for Astronomy Main Lesson

Summary Sheet #1 for Astronomy Main Lesson From our perspective on earth The earth appears flat. We can see half the celestial sphere at any time. The earth s axis is always perpendicular to the equator.

### Physical Science. Chapter 22 The Earth in Space. Earth s Rotation

Physical Science Chapter 22 The Earth in Space Earth s Rotation Axis imaginary line passing through the North and South Pole Earth s axis is tilted at 23 ½ degrees Rotation: the Earth spinning on its axis

### The Earth-Moon-Sun System

chapter 7 The Earth-Moon-Sun System section 2 Time and Seasons What You ll Learn how to calculate time and date in different time zones how to distinguish rotation and revolution what causes seasons Before

### 1. The pictures below show the Sun at midday. Write winter, spring or summer under the correct picture.

Test 2 1. The pictures below show the Sun at midday. Write winter, spring or summer under the correct picture. 2. Look carefully at the phases of the Moon. Number them (1 to 4) in the order that you would

### Astronomy 100 Section 2 MWF Greg Hall

Astronomy 100 Section 2 MWF 1200-1300 100 Greg Hall Leslie Looney Phone: 217-244-3615 Email: lwl @ uiuc. edu Office: Astro Building #218 Office Hours: MTF 10:30-11:30 a.m. or by appointment Class Web Page

### (1) How does the annual average sun angle at solar noon (that is, the sun angle at noon averaged over a full year) depend on latitude?

(1) How does the annual average sun angle at solar noon (that is, the sun angle at noon averaged over a full year) depend on latitude? (A) * As latitude increases, average sun angle at solar noon decreases.

### Aim: What causes Seasons?

Notepack 28 Aim: What causes Seasons? Do Now: What is the difference between revolution and rotation? Earth s rotation The Earth rotates on its axis (imaginary vertical line around which Earth spins) every

### Viewed from Earth's north pole, the rotation of Earth and its moon are counter-clockwise.!

The Earth rotates around once in 24 hours The time it takes for the Earth to rotate completely around once is what we call a day. It's Earth's rotation that gives us night and day. Viewed from Earth's

### Astronomy Review. Use the following four pictures to answer questions 1-4.

Astronomy Review Use the following four pictures to answer questions 1-4. 1. Put an X through the pictures that are NOT possible. 2. Circle the picture that could be a lunar eclipse. 3. Triangle the picture

### Lecture 2: Motions of the Earth and Moon. Astronomy 111 Wednesday August 30, 2017

Lecture 2: Motions of the Earth and Moon Astronomy 111 Wednesday August 30, 2017 Reminders Online homework #1 due Monday at 3pm Labs start next week Motions of the Earth ASTR111 Lecture 2 Observation:

### Discovering the Universe for Yourself (Chapter 2) Years, Seasons, and Months: The Motions of Sun, Earth, and Moon

Discovering the Universe for Yourself (Chapter 2) Years, Seasons, and Months: The Motions of Sun, Earth, and Moon Based on Chapter 2 This material will be useful for understanding Chapters 3 and 4 on The

### Solar System Glossary. The point in an object s elliptical orbit farthest from the body it is orbiting

Solar System Glossary Apogee Atmosphere Asteroid Axis Autumn Barred spiral The point in an object s elliptical orbit farthest from the body it is orbiting The air that surrounds Earth and other planets

### Brock University. Test 1, May 2014 Number of pages: 9 Course: ASTR 1P01 Number of Students: 500 Date of Examination: May 21, 2014

Brock University Test 1, May 2014 Number of pages: 9 Course: ASTR 1P01 Number of Students: 500 Date of Examination: May 21, 2014 Number of hours: 50 min Time of Examination: 14:00 14:50 Instructor: B.Mitrović

### The Earth, Moon, and Sky. Lecture 5 1/31/2017

The Earth, Moon, and Sky Lecture 5 1/31/2017 From Last Time: Stable Orbits The type of orbit depends on the initial speed of the object Stable orbits are either circular or elliptical. Too slow and gravity

### The Sun-Earth-Moon System

chapter 311 section 1 Earth The Sun-Earth-Moon System Before You Read What do you already know about Earth s shape, its size, and how it moves? Write what you know on the lines below. What You ll Learn

### Astr 1050 Mon. Jan. 31, 2017

Astr 1050 Mon. Jan. 31, 2017 Finish Ch. 2: Eclipses & Planetary Motion Seasons Angular Size formula Eclipses Planetary Motion Reading: For Today: Finish Chapter 2 For Monday: Start Chapter 3 Homework on

### What causes the seasons? 2/11/09

2/11/09 We can recognize solstices and equinoxes by Sun s path across sky: Summer solstice: Highest path, rise and set at most extreme north of due east. Winter solstice: Lowest path, rise and set at most

### REVIEW CH #0. 1) Right ascension in the sky is very similar to latitude on the Earth. 1)

REVIEW CH #0 TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 1) Right ascension in the sky is very similar to latitude on the Earth. 1) 2) Latitude and right ascension

### Tutoring information, as announced in class

Announcements Register for Connect, register your iclickers - Register iclickers at https://www1.iclicker.com/ or REEF account profile - Purchase the REEF polling app, create an account, register and get

### Syllabus, Semester Project, Scales/Scale Models. Questions? One comment

Syllabus, Semester Project, Scales/Scale Models Questions? One comment Patterns in the Sky: Traxoline Cardinal Directions (N, S, E, W) Positions in the Sky ( high, low ) Meridian, Zenith, Horizon Noon

### Chapters 1, 2: Introduction, Earth and Sky

Chapters 1, 2: Introduction, Earth and Sky Orientation to the Universe - sizes and distances Frames of Reference: equator, ecliptic, horizon The Seasons Eclipses of the sun and moon Key Points The most

### Brock University. Test 1, September 2014 Number of pages: 9 Course: ASTR 1P01 Number of Students: 500 Date of Examination: September 29, 2014

Brock University Test 1, September 2014 Number of pages: 9 Course: ASTR 1P01 Number of Students: 500 Date of Examination: September 29, 2014 Number of hours: 50 min Time of Examination: 18:00 18:50 Instructor:

### 8 th Grade Earth, Moon and Sun Systems Review

8 th Grade Earth, Moon and Sun Systems Review #1 Click on the link to learn What causes Seasons? A #2 H G B D C What is season A in this diagram? E F A: Summer B: Fall C: Winter D: Spring D. Spring A #3

### STANDARD. S6E1 d. Explain the motion of objects in the day/night sky in terms of relative position.

STANDARD S6E1 d. Explain the motion of objects in the day/night sky in terms of relative position. S6E2 b. Explain the alignment of the earth, moon, and sun during solar and lunar eclipses. c. Relate the

### Phases of the Moon. Two perspectives: On Earth, or outside the Moon s orbit. More Phases. What if we zoom out? Phases of the Moon Demo 2/3/17

Phases of the Moon The Moon goes through a set of phases about once every month Month comes from the word moon Time period of the phases (from Full Moon to Full Moon) is 29.5 days. The different phases

### Brock University. Test 1, October 2016 Number of pages: 9 Course: ASTR 1P01 Number of Students: 500 Date of Examination: October 3, 2016

Brock University Test 1, October 2016 Number of pages: 9 Course: ASTR 1P01 Number of Students: 500 Date of Examination: October 3, 2016 Number of hours: 50 min Time of Examination: 17:00 17:50 Instructor:

### 2. Modern: A constellation is a region in the sky. Every object in the sky, whether we can see it or not, is part of a constellation.

6/14 10. Star Cluster size about 10 14 to 10 17 m importance: where stars are born composed of stars. 11. Galaxy size about 10 21 m importance: provide a stable environment for stars. Composed of stars.

### Name: Class: Date: ID: A

Name: Class: _ Date: _ Astro Quiz 2 (ch2) Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Star A has an apparent visual magnitude of 13.4 and star B has

### James T. Shipman Jerry D. Wilson Charles A. Higgins, Jr. Chapter 15 Place and Time

James T. Shipman Jerry D. Wilson Charles A. Higgins, Jr. Chapter 15 Place and Time Place & Time Read sections 15.5 and 15.6, but ignore the math. Concentrate on those sections that help explain the slides.

### Solar Noon The point at which the Sun is highest in the sky (and when shadows are shortest).

Solar Noon The point at which the Sun is highest in the sky (and when shadows are shortest). Rotation The movement of one object as it turns or spins around a central point or axis. Revolution The movement

### Astronomy 101: 9/18/2008

Astronomy 101: 9/18/2008 Announcements Pick up a golf ball at the front of the class or get one from Alex; you will need it for an in-class activity today. You will also need the question sheet from Alex.

### Discovering the Night Sky

Discovering the Night Sky Guiding Questions 1. What role did astronomy play in ancient civilizations? 2. Are the stars that make up a constellation actually close to one another? 3. Are the same stars

### Discovering the Night Sky

Guiding Questions Discovering the Night Sky 1. What role did astronomy play in ancient civilizations? 2. Are the stars that make up a constellation actually close to one another? 3. Are the same stars

### Astronomy 122 Section 1 TR Digital Computer Laboratory. Outline. Celestial Sphere. Motions in the Sky

Astronomy 122 Section 1 TR 1300-1350 1320 Digital Computer Laboratory Leslie Looney Phone: 244-3615 Email: lwlw@wuiucw. wedu Office: Astro Building #218 Office Hours: T 10:30-11:30 a.m. or by appointment

### Knowing the Heavens. Chapter Two. Guiding Questions. Naked-eye (unaided-eye) astronomy had an important place in ancient civilizations

Knowing the Heavens Chapter Two Guiding Questions 1. What role did astronomy play in ancient civilizations? 2. Are the stars that make up a constellation actually close to one another? 3. Are the same

### Earth, Sun, and Stars

Earth, Sun, and Stars Daily Patterns Earth Spins Earth is always moving, even though you don t feel it. One way Earth moves is by spinning around an imaginary line. One end of the line would come out of

### a. 0.5 AU b. 5 AU c. 50 AU d.* AU e AU

1 AST104 Sp04: WELCOME TO EXAM 1 Multiple Choice Questions: Mark the best answer choice. Read all answer choices before making selection. (No credit given when multiple answers are marked.) 1. A galaxy

### The Earth and the Sky

The Earth and the Sky In this class, we want to understand why the objects in the sky as seen from the Earth - appear as they do. Even though we haven t yet discussed the details, I am assuming that there

### Position 3. None - it is always above the horizon. Agree with student 2; star B never crosses horizon plane, so it can t rise or set.

Position 3 None - it is always above the horizon. N E W S Agree with student 2; star B never crosses horizon plane, so it can t rise or set. Imaginary plane No; the Earth blocks the view. Star A at position