The Size & Shape of the Galaxy

Save this PDF as:
 WORD  PNG  TXT  JPG

Size: px
Start display at page:

Download "The Size & Shape of the Galaxy"

Transcription

1 name The Size & Shape of the Galaxy The whole lab consists of plotting two graphs. What s the catch? Aha visualizing and understanding what you have plotted of course! Form the Earth Science Picture of the day at The above picture is a schematic diagram of our current understanding of the shape and the size of the Milky Way. But if you look up at the night sky, the Milky Way looks very different, because we view it from inside itself. So determining the shape and size of our own Galaxy is quite a challenge. In this lab, you will analyze some of the original data of Shapley and Curtis. Both of them came up with some right and some wrong conclusions about the size and shape of our galaxy, the Milky Way. Their results led to new philosophical interpretations about our location, role and importance in the universe. Both of them used scientific methodology to prove their points. Your (final) task in this lab is to analyze their methods and to conclude for yourselves whether or not you can believe their interpretations. The Size & Shape of the Galaxy Lab 11 1

2 Part I The Milky Way according to Shapley The appropriate location of the center of the Milky Way was discovered by Harlow Shapley seventy years ago. Today, we have now located the center more precisely by observing at infrared and radio wavelengths (these can penetrate dust, thus eliminating the problem of extinction). Shapley s method is interesting nonetheless, and it is an example of how some thought and educated guessing can lead to a correct result. Shapley used globular clusters to define the skeleton of the Milky Way. Globular clusters are compact groups of stars, which are roughly spherical in shape. A globular cluster may contain a million stars and is therefore much brighter than a single star. Thus they can be spotted at large distances. Shapley reasoned that since globular clusters can be identified at great distances, he might be able to determine the edge and the center of our Galaxy. In this exercise you will repeat Shapley s study using the data on globular clusters given in Table 1. Your task is to make two plots, one of RA versus Dec, and another one with x versus z. However the real part of this exercise is visualizing and understanding what you have plotted, and drawing conclusions from those plots. Table 1 Globular Cluster Positions NAME RA DEC x (kpc) z (kpc) 1 NGC h 10.1m -64 o NGC h 07.6m +18 o NGC h 10.5m +18 o NGC h 23.7m -47 o M 5 15h 16.0m +02 o M 80 16h 14.1m -22 o M 13 16h 39.9m +36 o M 19 16h 59.5m -26 o NGC h 07.1m -26 o M 9 17h 16.2m -18 o NGC h 25.1m -05 o M 14 17h 35.0m -03 o NGC h 36.8m -63 o NGC h 46.8m -37 o NGC h 00.4m -30 o NGC h 04.4m -43 o M 28 18h 21.5m -24 o M 22 18h 33.3m -23 o NGC h 56.2m -36 o NGC h 06.4m -60 o M 56 19h 14.6m +30 o M 75 20h 03.2m -22 o Lab 11 The Size & Shape of the Galaxy

3 A Understanding and Visualizing the RA/Dec Plot 1) Write down the definitions of RA and dec and compare them to latitude and longitude. Base your answer on what you see in Figure 2. 2) Using the data in Table 1, make a plot of right ascension versus declination. (Plot your data into Figure 3. As in Figure 8, RA is along the x-axis and goes from 0 to 24 hours, Dec is on the y-axis and goes from +90 to 0 to 90 degrees.) 3) Visualize what you have drawn. Consult the Sky-Lab, the TOOLKIT and the plot below. You may want to orient the RA/dec plot in a similar fashion as the Figure below. Align the dec-axis in direction of the arrow pointing towards the North Celestial Sphere, and the RA-axis along the Celestial Equator. Declination Right Ascension Fig 2 The Size & Shape of the Galaxy Lab 11 3

4 4) Would you describe the distribution of clusters on the plot as random, or is there a pattern? 5) Now look at your plot and point in the direction in which you see most of the globular clusters. This is the general direction of the Galactic Center. Estimate the center of the distribution of the globular clusters. Also estimate (no calculation required just an educated estimate) the accuracy of determining this center. You have now determined the rough center of our Galaxy! RA = ± Dec = ± 6) Grab a Celestial Sphere from the shelf, and locate the position of the Galactic Center on the Celestial Sphere, i.e., locate the coordinates of RA and dec of the Galactic Center on the Celestial Sphere. In which constellation is the Galactic Center? The Galactic Center is in the constellation Most Celestial Spheres in the classroom have a drawing of the location of the Milky Way. Observe the Milky Way and convince yourself that your nominal position of the Galactic Center corresponds to the Center of the Milky Way on the Celestial Globe. 7) Orientate yourself. First answer the questions below, then show this to the instructor. a) In the classroom, locate the direction of North (e.g., Manhattan is northeast of Staten Island), then, using your fist, determine the position of Polaris (the altitude is 40 o ). Show your instructor the rough location of Polaris in the classroom. b) Also, show the location of the Celestial Equator in the classroom. c) Take the celestial sphere and orient it like you did in Sky-Lab-#1. [Position the Celestial Sphere so that the Zenith of a miniature person standing on the Globe in New York (see below) point to the same Zenith as you standing in the classroom (turn the Celestial Sphere until New York is at the top and pointing to the ceiling).] d) Locate the Galactic Center on the celestial sphere and point out where the Galactic Center would be projected onto the classroom wall. e) Does this location change throughout the day? f) If your answer is yes show your instructor how the Galactic Center appears to move the classroom. 4 Lab 11 The Size & Shape of the Galaxy

5 R.A. R.A. Dec Plot Dec = 90 o Dec Dec Dec Dec Dec =-90 o RA R.A.

6 8) Assuming you are in New York, make a drawing (label the Horizon, Celestial Equator and Polaris) for the moment of transit of the Galactic Center (i.e., turn the celestial sphere so that the Galactic Center reaches its highest possible altitude; the GC should then be on the Meridian). Now stand back and observe the shape of the rest of the Milky Way on the Celestial Sphere. Then draw in the disk of the Milky Way into the diagram below. Also draw the backside of the celestial sphere. Zenith NCP Fig 4 9) Now imagine that you slice this sphere open at RA=0 and you obtain plot 3. Compare this imaginary plot with plot 3. Observe the location of the entire disk of the Milky Way on the Celestial Sphere, and draw this disk into the RA/Dec Plot. How do the two plots compare? 10) Rotate the celestial sphere around its N-S axis and watch the path of the Galactic Center. Complete the diagram below (label the Zenith, Horizon, Celestial Equator and Polaris), showing this path throughout the night. Zenith NCP Fig 5

7 B Visualizing the x/z Plot Shapely was correct in thinking that the distribution of globular clusters could reveal something about the Galaxy as a whole. He went one step further. He used the locations of the globular clusters to determine the distance to the Galactic Center. His result was surprisingly accurate and differed from the modern value by less than 10%. So, let s follow in his footsteps. The next step is to determine the distance to the clusters. Shapely did this by using RR Lyrae stars. These are variable stars, which have a relatively narrow range of luminosities. From the difference between the apparent magnitudes (measured from his photographic plates) and the absolute magnitudes (calculated from the luminosities), he calculated the distances (via: m - M = 5logd - 5). You have done this in the Photometry and the Spectroscopy Labs! So now we have the distances and the directions of the globular clusters and we can determine the 3- dimentional distributions of the globular clusters relative to us. However, we will use a different coordinate system that is based on galactic latitude and longitude rather than RA and Dec. The plane of the Galaxy is designated as 0 latitude. Why would we want to do this? RA and Dec is a messy coordinate system that depends on our orientation in space and the earth s rotation around its axis. The system based on galactic latitude and longitude is therefore simpler. However, it means that we have to transform the measured RA and DEC positions of the globular clusters and galactic latitude and longitude. To simplify things even further, let s express the galactic latitude and longitude in terms of x, y, and z coordinates. The advantage of this is that x, y, and z have units of parsecs (rather than angles which is the case with galactic latitude and longitude). So now the z-coordinate tells us how far above or below the galactic plane we are, and the x-coordinate tells us how far away from the origin (in this case from the Galactic Center) we are! This is illustrated below. The y-coordinate tells us where in the x-y plane (in the Galactic Disk) we would be found (actually, where along the gray circle we would be). But since we assume that the disk is a round circle (i.e., it is symmetric), we only need to worry about the distance from the center in the disk. Basically, we are only concerned about two quantities: x and z, i.e., how far above and below the Galactic Disk the globular clusters can be found, and far away from the Galactic Center they are. z-axis z is distance above or below the x-y plane y-axis x-axis x-y plane corresponds to disk of galaxy The Size & Shape of the Galaxy Lab 11 7

8 Maybe all this coordinate system stuff may sound confusing, but all you need to know is that they basically express the same thing locations in space. However we can nevertheless try to visualize how these different coordinate systems describe the locations of objects in space. The diagram below shows this. You can see the Galactic Disk (the x-y plane) and the Galactic Center. Imagine that there is also another coordinate: everything that is located either above or below this disk (the z-axis). You can also see the location of our Earth: it is in the Galactic Disk but some distance away from the Galactic Center. However when on Earth we describe what we see in the sky relative to the North Pole and the Equator. (The direction of the North Pole from the Earth is shown in red. Perpendicular to that is the Celestial Equator.) And looking up the sky we see the Milky Way (like below) in the plane of the Galaxy. z NCP x Galactic Plane Earth Fig 6 This figure is taken from Chaisson and McMIllian s book Astronomy Today The mathematical transformation from RA and Dec to galactic longitude and latitude and then to x and z is a little messy, so this step has been done for you. Table 1 lists the final values of x and z. Your next task is to make this plot, and determine our location (the Sun s location!) in the Galaxy, the distance to the Galactic Center, and the size and shape of our Galaxy. After you have plotted the globular clusters, you ll see why we bothered transforming between all these coordinate systems. 8 Lab 11 The Size & Shape of the Galaxy

9 Understanding the x/z Plot 1) Plot x against z. 2) In Plot 2, the x-axis points towards the Galactic Center (same arrow as in Figure 6); the z-axis is perpendicular to that, with positive numbers pointing up, and negative numbers pointing down. Visualize what you have plotted. Understand which additional information you obtain from this plot. Plot 1 only tells you about the directions in which you see the globular clusters (the globular clusters are draw onto the celestial sphere and you have no idea about their distances). Plot 2 tells you about real distances (in kilo-parsecs) of globular clusters; i.e., how far above and below the galactic plane they are located, and how far away they are from us. (Note that the third dimension, the y-axis, is collapsed into the plane of the disk of the galaxy we only know how far away from the galactic center the globular clusters are found, we do not know where in the disk they are. However this is not important right now when trying to visualize this plot.) 3) Label the x and z-axis in Figure 6. Compare Plot 2 to Figure 6. Position yourself into the origin of Plot 2 (i.e., at x=0, z=0) and point the x-axis towards the Galactic Center of Figure 6. The x-axis then shows you HOW FAR away each globular cluster is from you in the direction of the Galactic center. The z-axis tells you how far above or below the galactic plane that globular cluster is located. 4) Sketch the Galaxy. Identify the disk, the bulge, and the halo of the Galaxy. Clearly label each component. [Remember that this is a two-dimensional drawing: the y-axis is collapsed into the plane of the Galaxy (i.e., the y-axis has been eliminated); you are only looking at the x-z plane]. 5) Assume that the center of the Galaxy is in the center of the distribution of the globular clusters. Figure out where you could draw a line parallel to the z-axis (the vertical axis) such that equal numbers of clusters fall on each side of the line. So then, the z-coordinate of the center should be set to 0. Using a pen of a different color mark the new scale in your plot. 6) Most globular clusters are located in a narrow range above and below the galactic plane. Roughly how may kiloparsecs above and below the galactic place are those globular clusters (i.e., how thick is the disk of the Galaxy in kilo-parsecs)? Estimate the uncertainty in that number. Thickness of Galactic Disk = ± kpc 7) Measure the distance in kilo-parsecs from you to the central point in the distribution of the globular clusters. How many kilo-parsecs away is the center? Estimate the uncertainty in that number. Distance to Galactic Center = ± kpc 8) How far above or below the Disk of The Galaxy would you place our Solar System? Distance to Disk of the Galaxy = ± kpc The Size & Shape of the Galaxy Lab 11 9

10 9) From that plot, what diameter would you infer for the disk of the Galaxy? Diameter of Disk of Galaxy = ± kpc 10) What diameter would you infer for the halo of the Galaxy? Diameter of Halo of Galaxy = ± kpc 11) We now know that the interstellar dust obscures much of the Galaxy from our view. The true center of the Galaxy suffers from a level of extinction that makes it appear 30 magnitudes fainter in visible light than it would appear without any presence of dust (this is when infrared or radio observations come in handy). What about the globular clusters in (a) the Galactic Center, (b) in the Disk away from the Galactic Center, and (c) in the Halo? Do you think dust could distort those quantities equally? Give a sentence or two of justification for each of your answers. 12) Look at your answers in parts 6, 7, 8, and 9. Which of those quantities have the largest uncertainty, which ones the least? Explain. 13) You have just plotted some of Shapley s original data. Now think about the conclusions he came up with! He figured out the location of the Galactic Center, he figured out the distance to the Galactic center, and he also concluded that there is a Halo of globular clusters surrounding the disk of the Galaxy. Would you have trusted the conclusions he came up with??? 10 Lab 11 The Size & Shape of the Galaxy

11 "x-z" Plot 25 Distance in kpc of our Plane relative to Disk of Galaxy Earth Distance in kpc from us in Disk of Galaxy Mark and label the x and z-axis Label the Galactic Center The Size & Shape of the Galaxy Lab 11 11

12 Part II Distribution of Novae Let s compare the data on globular clusters to data on novae. The work has been done for you and the distribution of the novae have been plotted. Your task is to understand and interpret this plot. 1) Compare Figures 3 and 8 the distribution of globular clusters to the distribution of novae. a) Sketch the Milky Way onto Figure 8, the plot of the novae. b) Determine the position of the Galactic Center from Figure 8. Estimate the uncertainties. RA = ± Dec = ± c) Figure 8 seems to have an additional arc of points for right ascensions ranging from 0 to 12 hours. What is this? Is this some type of illusion, or was that omitted in Figure 3? Explain. d) Compare the distributions of globular clusters and novae. Is the bulge equally big? Comment. e) Is the disk equally thick? Comment. f) Mark the globular clusters and nova in the halo of Figures 3 AND 8. g) Are there equally many halo objects? Comment. 12 Lab 11 The Size & Shape of the Galaxy

13 2) Would you expect to derive the same overall shape of the Galaxy from both data? Explain 3) In the Pre-Lab you read about the Curtis-Shapley debate. Based on what you have plotted decide on who of the two is more right about the shape of the Galaxy. Explain your reasoning. 4) Good News There is no separate Lab Report! The Size & Shape of the Galaxy Lab 11 13

14 14 Lab 11 The Size & Shape of the Galaxy

Orientation to the Sky: Apparent Motions

Orientation to the Sky: Apparent Motions Chapter 2 Orientation to the Sky: Apparent Motions 2.1 Purpose The main goal of this lab is for you to gain an understanding of how the sky changes during the night and over the course of a year. We will

More information

CELESTIAL CLOCK - THE SUN, THE MOON, AND THE STARS

CELESTIAL CLOCK - THE SUN, THE MOON, AND THE STARS INTRODUCTION CELESTIAL CLOCK - THE SUN, THE MOON, AND THE STARS This is a scientific presentation to provide you with knowledge you can use to understand the sky above in relation to the earth. Before

More information

The Celestial Sphere. Questions for Today. The Celestial Sphere 1/18/10

The Celestial Sphere. Questions for Today. The Celestial Sphere 1/18/10 Lecture 3: Constellations and the Distances to the Stars Astro 2010 Prof. Tom Megeath Questions for Today How do the stars move in the sky? What causes the phases of the moon? What causes the seasons?

More information

Which month has larger and smaller day time?

Which month has larger and smaller day time? ACTIVITY-1 Which month has larger and smaller day time? Problem: Which month has larger and smaller day time? Aim: Finding out which month has larger and smaller duration of day in the Year 2006. Format

More information

12-3. Spherical groups of millions of stars found in the Milky Way are called: a) novas b) globular clusters X c) open clusters d) galactic clusters

12-3. Spherical groups of millions of stars found in the Milky Way are called: a) novas b) globular clusters X c) open clusters d) galactic clusters Chapter 12 Quiz, Nov. 28, 2012, Astro 162, Section 4 12-1. Where in our Galaxy has a supermassive (or galactic) black hole been observed? a) at the outer edge of the nuclear bulge b) in the nucleus X c)

More information

Solar Angles and Latitude

Solar Angles and Latitude Solar Angles and Latitude Objectives The student will understand that the sun is not directly overhead at noon in most latitudes. The student will research and discover the latitude ir classroom and calculate

More information

Using Photometric Data to Derive an HR Diagram for a Star Cluster

Using Photometric Data to Derive an HR Diagram for a Star Cluster Using Photometric Data to Derive an HR Diagram for a Star Cluster In In this Activity, we will investigate: 1. How to use photometric data for an open cluster to derive an H-R Diagram for the stars and

More information

Finding Stars and Constellations Earth & Sky

Finding Stars and Constellations Earth & Sky Finding Stars and Constellations Earth & Sky Name: Introduction If you carefully watched the night sky over a period of time, you would notice that it s not always the same. There are certain changes that

More information

AST101: Our Corner of the Universe Lab 2: The Sun and Phases of The Moon

AST101: Our Corner of the Universe Lab 2: The Sun and Phases of The Moon AST101: Our Corner of the Universe Lab 2: The Sun and Phases of The Moon Name: NetID (your SU email address, without the @syr.edu): Lab section number: 1 Introduction Objectives The first part of this

More information

Basic Coordinates & Seasons Student Guide

Basic Coordinates & Seasons Student Guide Name: Basic Coordinates & Seasons Student Guide There are three main sections to this module: terrestrial coordinates, celestial equatorial coordinates, and understanding how the ecliptic is related to

More information

THE STARRY SKY AST MESA COMMUNITY COLLEGE

THE STARRY SKY AST MESA COMMUNITY COLLEGE NAME: DATE: INTRODUCTION This lab exercise introduces the arrangement and motions of the stars, constellations, and other objects of the night sky. LEARNING GOALS Describe the motions of stars during a

More information

CELESTIAL MOTIONS. In Charlottesville we see Polaris 38 0 above the Northern horizon. Earth. Starry Vault

CELESTIAL MOTIONS. In Charlottesville we see Polaris 38 0 above the Northern horizon. Earth. Starry Vault CELESTIAL MOTIONS Stars appear to move counterclockwise on the surface of a huge sphere the Starry Vault, in their daily motions about Earth Polaris remains stationary. In Charlottesville we see Polaris

More information

Lecture 6: distribution of stars in. elliptical galaxies

Lecture 6: distribution of stars in. elliptical galaxies Lecture 6: distribution of stars in topics: elliptical galaxies examples of elliptical galaxies different classes of ellipticals equation for distribution of light actual distributions and more complex

More information

In studying the Milky Way, we have a classic problem of not being able to see the forest for the trees.

In studying the Milky Way, we have a classic problem of not being able to see the forest for the trees. In studying the Milky Way, we have a classic problem of not being able to see the forest for the trees. A panoramic painting of the Milky Way as seen from Earth, done by Knut Lundmark in the 1940 s. The

More information

Where on Earth are the daily solar altitudes higher and lower than Endicott?

Where on Earth are the daily solar altitudes higher and lower than Endicott? Where on Earth are the daily solar altitudes higher and lower than Endicott? In your notebooks, write RELATIONSHIPS between variables we tested CAUSE FIRST EFFECT SECOND EVIDENCE As you increase the time

More information

Coordinate Systems. Orbits and Rotation

Coordinate Systems. Orbits and Rotation Coordinate Systems Orbits and Rotation Earth orbit. The earth s orbit around the sun is nearly circular but not quite. It s actually an ellipse whose average distance from the sun is one AU (150 million

More information

Pre and post-visit activities - Navigating by the stars

Pre and post-visit activities - Navigating by the stars Pre and post-visit activities - Navigating by the stars Vocabulary List Adult Education at Scienceworks Pre-visit Activity 1: What is longitude and latitude? Activity 2: Using the Southern Cross to find

More information

Celestial Observations

Celestial Observations Celestial Observations Earth experiences two basic motions: Rotation West-to-East spinning of Earth on its axis (v rot = 1770 km/hr) (v rot Revolution orbit of Earth around the Sun (v orb = 108,000 km/hr)

More information

Stellarium a valuable resource for teaching astronomy in the classroom and beyond

Stellarium a valuable resource for teaching astronomy in the classroom and beyond Stellarium 1 Stellarium a valuable resource for teaching astronomy in the classroom and beyond Stephen Hughes Department of Physical and Chemical Sciences, Queensland University of Technology, Gardens

More information

EDMONDS COMMUNITY COLLEGE ASTRONOMY 100 Winter Quarter 2007 Sample Test # 1

EDMONDS COMMUNITY COLLEGE ASTRONOMY 100 Winter Quarter 2007 Sample Test # 1 Instructor: L. M. Khandro EDMONDS COMMUNITY COLLEGE ASTRONOMY 100 Winter Quarter 2007 Sample Test # 1 1. An arc second is a measure of a. time interval between oscillations of a standard clock b. time

More information

OBJECT: To become familiar with some of the motions of the stars, Sun, Moon and planets as seen from the surface of the Earth.

OBJECT: To become familiar with some of the motions of the stars, Sun, Moon and planets as seen from the surface of the Earth. INSIDE LAB 2: Celestial Motions OBJECT: To become familiar with some of the motions of the stars, Sun, Moon and planets as seen from the surface of the Earth. DISCUSSION: As seen from a point of view centered

More information

Celestial Sphere. Celestial Coordinates. Lecture 3: Motions of the Sun and Moon. ecliptic (path of Sun) ecliptic (path of Sun)

Celestial Sphere. Celestial Coordinates. Lecture 3: Motions of the Sun and Moon. ecliptic (path of Sun) ecliptic (path of Sun) Lecture 3: Motions of the and Moon ecliptic (path of ) ecliptic (path of ) The 23.5 degree tilt of Earth s spin axis relative to its orbital axis around the causes the seasons Celestial Sphere Celestial

More information

1. In the diagram below, the direct rays of the Sun are striking the Earth's surface at 23 º N. What is the date shown in the diagram?

1. In the diagram below, the direct rays of the Sun are striking the Earth's surface at 23 º N. What is the date shown in the diagram? 1. In the diagram below, the direct rays of the Sun are striking the Earth's surface at 23 º N. What is the date shown in the diagram? 5. During how many days of a calendar year is the Sun directly overhead

More information

Section 1.8 Coordinate Geometry

Section 1.8 Coordinate Geometry Section 1.8 Coordinate Geometry The Coordinate Plane Just as points on a line can be identified with real numbers to form the coordinate line, points in a plane can be identified with ordered pairs of

More information

The following words and their definitions should be addressed before completion of the reading:

The following words and their definitions should be addressed before completion of the reading: Seasons Vocabulary: The following words and their definitions should be addressed before completion of the reading: sphere any round object that has a surface that is the same distance from its center

More information

SECOND GRADE 1 WEEK LESSON PLANS AND ACTIVITIES

SECOND GRADE 1 WEEK LESSON PLANS AND ACTIVITIES SECOND GRADE 1 WEEK LESSON PLANS AND ACTIVITIES UNIVERSE CYCLE OVERVIEW OF SECOND GRADE UNIVERSE WEEK 1. PRE: Discovering stars. LAB: Analyzing the geometric pattern of constellations. POST: Exploring

More information

Origins of the Cosmos Summer 2016. Pre-course assessment

Origins of the Cosmos Summer 2016. Pre-course assessment Origins of the Cosmos Summer 2016 Pre-course assessment In order to grant two graduate credits for the workshop, we do require you to spend some hours before arriving at Penn State. We encourage all of

More information

COASTLINING THE ZODIAC

COASTLINING THE ZODIAC COASTLINING THE ZODIAC Astronomy books and skywatching guides offer a wide variety of charts for naked-eye observation of the skies. What works best for each person will depend on various factors such

More information

1-2. What is the name given to the path of the Sun as seen from Earth? a.) Equinox b.) Celestial equator c.) Solstice d.

1-2. What is the name given to the path of the Sun as seen from Earth? a.) Equinox b.) Celestial equator c.) Solstice d. Chapter 1 1-1. How long does it take the Earth to orbit the Sun? a.) one sidereal day b.) one month c.) one year X d.) one hour 1-2. What is the name given to the path of the Sun as seen from Earth? a.)

More information

Full credit for this chapter to Prof. Leonard Bachman of the University of Houston

Full credit for this chapter to Prof. Leonard Bachman of the University of Houston Chapter 6: SOLAR GEOMETRY Full credit for this chapter to Prof. Leonard Bachman of the University of Houston SOLAR GEOMETRY AS A DETERMINING FACTOR OF HEAT GAIN, SHADING AND THE POTENTIAL OF DAYLIGHT PENETRATION...

More information

Distribution of Globular Clusters and Young Star Groups on the Sky. x x x

Distribution of Globular Clusters and Young Star Groups on the Sky. x x x PENN STATE ASTRONOMY LABORATORY è 11 THE STRUCTURE OF THE MILKY WAY GALAXY I. Objective In this lab, yu will learn that we live in the Milky Way Galay. Our slar system and all the stars yu can see with

More information

A Dialogue Box. dialogue box.

A Dialogue Box. dialogue box. The Sky An introduction and review 1. Open TheSky (version 6, the blue icon). The screen should show the view of the sky looking due south. Even if the sun is above the horizon, the sky will look black

More information

First Discoveries. Asteroids

First Discoveries. Asteroids First Discoveries The Sloan Digital Sky Survey began operating on June 8, 1998. Since that time, SDSS scientists have been hard at work analyzing data and drawing conclusions. This page describes seven

More information

Experiment 5: Magnetic Fields of a Bar Magnet and of the Earth

Experiment 5: Magnetic Fields of a Bar Magnet and of the Earth MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Physics 8.02 Spring 2005 Experiment 5: Magnetic Fields of a Bar Magnet and of the Earth OBJECTIVES 1. To examine the magnetic field associated with a

More information

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

Chapter 2 Review Clickers. The Cosmic Perspective Seventh Edition. Discovering the Universe for Yourself Pearson Education, Inc. Review Clickers The Cosmic Perspective Seventh Edition Discovering the Universe for Yourself The sky is divided into 88 zones called a) degrees. b) tropics. c) constellations. d) signs. The sky is divided

More information

Solar System. 1. The diagram below represents a simple geocentric model. Which object is represented by the letter X?

Solar System. 1. The diagram below represents a simple geocentric model. Which object is represented by the letter X? Solar System 1. The diagram below represents a simple geocentric model. Which object is represented by the letter X? A) Earth B) Sun C) Moon D) Polaris 2. Which object orbits Earth in both the Earth-centered

More information

Precise Polar Alignment (Drift Alignment)

Precise Polar Alignment (Drift Alignment) Precise Polar Alignment (Drift Alignment) OCA AstroImagers Boot Camp March 23, 2006 Dick Greenwald 1 Overview Basics Definition Why drift align? Basic polar alignment methods Error sources Precise polar

More information

The Seasons on a Planet like Earth

The Seasons on a Planet like Earth The Seasons on a Planet like Earth As the Earth travels around the Sun, it moves in a giant circle 300 million kilometers across. (Well, it is actually a giant ellipse but the shape is so close to that

More information

Newton s Law of Gravity

Newton s Law of Gravity Gravitational Potential Energy On Earth, depends on: object s mass (m) strength of gravity (g) distance object could potentially fall Gravitational Potential Energy In space, an object or gas cloud has

More information

Douglas Adams The Hitchhikers Guide to the Galaxy

Douglas Adams The Hitchhikers Guide to the Galaxy There is a theory which states that if ever anybody discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable.

More information

HR Diagram Student Guide

HR Diagram Student Guide Name: HR Diagram Student Guide Background Information Work through the background sections on Spectral Classification, Luminosity, and the Hertzsprung-Russell Diagram. Then complete the following questions

More information

Lunar Phase Simulator Student Guide

Lunar Phase Simulator Student Guide Name: Lunar Phase Simulator Student Guide Part I: Background Material Answer the following questions after reviewing the background pages for the simulator. Page 1 Introduction to Moon Phases Is there

More information

APPENDIX D: SOLAR RADIATION

APPENDIX D: SOLAR RADIATION APPENDIX D: SOLAR RADIATION The sun is the source of most energy on the earth and is a primary factor in determining the thermal environment of a locality. It is important for engineers to have a working

More information

SUPPLEMENT 2. ESTIMATING THE EPOCHS OF THE GCC AND GA

SUPPLEMENT 2. ESTIMATING THE EPOCHS OF THE GCC AND GA Crucifying the Earth on the Galactic Cross. upplement 2 1 UPPLEMENT 2. ETIMATING THE EPOCH OF THE GCC AND GA 2.1. OLAR YTEM AND GALACTIC PARAMETER Coordinate ystems. In the Equatorial and al coordinate

More information

Exercise 5.0 LUNAR MOTION, ELONGATION, AND PHASES

Exercise 5.0 LUNAR MOTION, ELONGATION, AND PHASES Exercise 5.0 LUNAR MOTION, ELONGATION, AND PHASES I. Introduction The Moon's revolution in orbit around the center of gravity (barycenter) of the Earth- Moon System results in an apparent motion of the

More information

Observing the Constellations of the Zodiac

Observing the Constellations of the Zodiac Observing the Constellations of the Zodiac Activity UCIObs 3 Grade Level: 8 12 Source: Copyright (2009) by Tammy Smecker Hane. Contact tsmecker@uci.edu with any questions. Standards:This activity addresses

More information

Lecture 8 : Coordinate Geometry. The coordinate plane The points on a line can be referenced if we choose an origin and a unit of 20

Lecture 8 : Coordinate Geometry. The coordinate plane The points on a line can be referenced if we choose an origin and a unit of 20 Lecture 8 : Coordinate Geometry The coordinate plane The points on a line can be referenced if we choose an origin and a unit of 0 distance on the axis and give each point an identity on the corresponding

More information

The Four Seasons. A Warm Up Exercise. A Warm Up Exercise. A Warm Up Exercise. The Moon s Phases

The Four Seasons. A Warm Up Exercise. A Warm Up Exercise. A Warm Up Exercise. The Moon s Phases The Four Seasons A Warm Up Exercise What fraction of the Moon s surface is illuminated by the Sun (except during a lunar eclipse)? a) Between zero and one-half b) The whole surface c) Always half d) Depends

More information

Tropical Horticulture: Lecture 2

Tropical Horticulture: Lecture 2 Lecture 2 Theory of the Tropics Earth & Solar Geometry, Celestial Mechanics The geometrical relationship between the earth and sun is responsible for the earth s climates. The two principal movements of

More information

TELESCOPE AS TIME MACHINE

TELESCOPE AS TIME MACHINE TELESCOPE AS TIME MACHINE Read this article about NASA s latest high-tech space telescope. Then, have fun doing one or both of the word puzzles that use the important words in the article. A TELESCOPE

More information

Reasons for Seasons. Question: TRUE OR FALSE. Question: TRUE OR FALSE? What causes the seasons? What causes the seasons?

Reasons for Seasons. Question: TRUE OR FALSE. Question: TRUE OR FALSE? What causes the seasons? What causes the seasons? Reasons for Seasons Question: TRUE OR FALSE? Earth is closer to the Sun in summer and farther from the Sun in winter. Question: TRUE OR FALSE? Earth is closer to the Sun in summer and farther from the

More information

SIERRA COLLEGE OBSERVATIONAL ASTRONOMY LABORATORY EXERCISE NUMBER III.F.a. TITLE: ASTEROID ASTROMETRY: BLINK IDENTIFICATION

SIERRA COLLEGE OBSERVATIONAL ASTRONOMY LABORATORY EXERCISE NUMBER III.F.a. TITLE: ASTEROID ASTROMETRY: BLINK IDENTIFICATION SIERRA COLLEGE OBSERVATIONAL ASTRONOMY LABORATORY EXERCISE NUMBER III.F.a. TITLE: ASTEROID ASTROMETRY: BLINK IDENTIFICATION DATE- PRINT NAME/S AND INITIAL BELOW: GROUP DAY- LOCATION OBJECTIVE: Use CCD

More information

EARTH'S MOTIONS. 2. The Coriolis effect is a result of Earth's A tilted axis B orbital shape C revolution D rotation

EARTH'S MOTIONS. 2. The Coriolis effect is a result of Earth's A tilted axis B orbital shape C revolution D rotation EARTH'S MOTIONS 1. Which hot spot location on Earth's surface usually receives the greatest intensity of insolation on June 21? A Iceland B Hawaii C Easter Island D Yellowstone 2. The Coriolis effect is

More information

Aileen A. O Donoghue Priest Associate Professor of Physics

Aileen A. O Donoghue Priest Associate Professor of Physics SOAR: The Sky in Motion y Life on the Tilted Teacup Ride Phases of the Moon Aileen A. O Donoghue Priest Associate Professor of Physics Kiva December 1997 October 27, 2009 Celestial Coordinates Right Ascension

More information

Sun Earth Relationships

Sun Earth Relationships 1 ESCI-61 Introduction to Photovoltaic Technology Sun Earth Relationships Ridha Hamidi, Ph.D. Spring (sun aims directly at equator) Winter (northern hemisphere tilts away from sun) 23.5 2 Solar radiation

More information

Motions of Earth, Moon, and Sun

Motions of Earth, Moon, and Sun Motions of Earth, Moon, and Sun Apparent Motions of Celestial Objects An apparent motion is a motion that an object appears to make. Apparent motions can be real or illusions. When you see a person spinning

More information

An Introduction to Astronomy and Cosmology. 1) Astronomy - an Observational Science

An Introduction to Astronomy and Cosmology. 1) Astronomy - an Observational Science An Introduction to Astronomy and Cosmology 1) Astronomy - an Observational Science Why study Astronomy 1 A fascinating subject in its own right. The origin and Evolution of the universe The Big Bang formation

More information

11.1. Objectives. Component Form of a Vector. Component Form of a Vector. Component Form of a Vector. Vectors and the Geometry of Space

11.1. Objectives. Component Form of a Vector. Component Form of a Vector. Component Form of a Vector. Vectors and the Geometry of Space 11 Vectors and the Geometry of Space 11.1 Vectors in the Plane Copyright Cengage Learning. All rights reserved. Copyright Cengage Learning. All rights reserved. 2 Objectives! Write the component form of

More information

Student Guide to the Lunar Phase Explorer Applet

Student Guide to the Lunar Phase Explorer Applet Nebraska Astronomy Applet Project Student Guide to the Lunar Phase Explorer Applet Pre-test in EDU Before working through the student guide, take the EDU pre-test and record your score at right. Background

More information

astronomy 2008 1. A planet was viewed from Earth for several hours. The diagrams below represent the appearance of the planet at four different times.

astronomy 2008 1. A planet was viewed from Earth for several hours. The diagrams below represent the appearance of the planet at four different times. 1. A planet was viewed from Earth for several hours. The diagrams below represent the appearance of the planet at four different times. 5. If the distance between the Earth and the Sun were increased,

More information

Science Standard 4 Earth in Space Grade Level Expectations

Science Standard 4 Earth in Space Grade Level Expectations Science Standard 4 Earth in Space Grade Level Expectations Science Standard 4 Earth in Space Our Solar System is a collection of gravitationally interacting bodies that include Earth and the Moon. Universal

More information

Size and Scale of the Universe

Size and Scale of the Universe Size and Scale of the Universe (Teacher Guide) Overview: The Universe is very, very big. But just how big it is and how we fit into the grand scheme can be quite difficult for a person to grasp. The distances

More information

Lesson 26: Reflection & Mirror Diagrams

Lesson 26: Reflection & Mirror Diagrams Lesson 26: Reflection & Mirror Diagrams The Law of Reflection There is nothing really mysterious about reflection, but some people try to make it more difficult than it really is. All EMR will reflect

More information

Worksheet Motion of the Sun and Moon

Worksheet Motion of the Sun and Moon Worksheet Motion of the Sun and Moon Apparent Motion of the Sun 1. The Earth makes one complete orbit around the Sun in one year. From the point of view of someone on the Earth this makes the Sun appear

More information

Section summaries. d = (x 2 x 1 ) 2 + (y 2 y 1 ) 2. 1 + y 2. x1 + x 2

Section summaries. d = (x 2 x 1 ) 2 + (y 2 y 1 ) 2. 1 + y 2. x1 + x 2 Chapter 2 Graphs Section summaries Section 2.1 The Distance and Midpoint Formulas You need to know the distance formula d = (x 2 x 1 ) 2 + (y 2 y 1 ) 2 and the midpoint formula ( x1 + x 2, y ) 1 + y 2

More information

Two vectors are equal if they have the same length and direction. They do not

Two vectors are equal if they have the same length and direction. They do not Vectors define vectors Some physical quantities, such as temperature, length, and mass, can be specified by a single number called a scalar. Other physical quantities, such as force and velocity, must

More information

For further information, and additional background on the American Meteorological Society s Education Program, please contact:

For further information, and additional background on the American Meteorological Society s Education Program, please contact: Project ATMOSPHERE This guide is one of a series produced by Project ATMOSPHERE, an initiative of the American Meteorological Society. Project ATMOSPHERE has created and trained a network of resource agents

More information

ASTR 115: Introduction to Astronomy. Stephen Kane

ASTR 115: Introduction to Astronomy. Stephen Kane ASTR 115: Introduction to Astronomy Stephen Kane ASTR 115: Introduction to Astronomy Textbook: The Essential Cosmic Perspective, 7th Edition Homework will be via the Mastering Astronomy web site: www.pearsonmastering.com

More information

Measuring Your Latitude from the Angle of the Sun at Noon

Measuring Your Latitude from the Angle of the Sun at Noon Measuring Your Latitude from the Angle of the Sun at Noon Background: You can measure your latitude in earth's northern hemisphere by finding out the altitude of the celestial equator from the southern

More information

Aphelion The point in the orbit of a planet or other celestial body where it is furthest from the Sun.

Aphelion The point in the orbit of a planet or other celestial body where it is furthest from the Sun. SKYTRACK Glossary of Terms Angular distance The angular separation between two objects in the sky as perceived by an observer, measured in angles. The angular separation between two celestial objects in

More information

Module 1 : A Crash Course in Vectors Lecture 2 : Coordinate Systems

Module 1 : A Crash Course in Vectors Lecture 2 : Coordinate Systems Module 1 : A Crash Course in Vectors Lecture 2 : Coordinate Systems Objectives In this lecture you will learn the following Define different coordinate systems like spherical polar and cylindrical coordinates

More information

Galaxy Classification and Evolution

Galaxy Classification and Evolution name Galaxy Classification and Evolution Galaxy Morphologies In order to study galaxies and their evolution in the universe, it is necessary to categorize them by some method. A classification scheme generally

More information

Exercise: Estimating the Mass of Jupiter Difficulty: Medium

Exercise: Estimating the Mass of Jupiter Difficulty: Medium Exercise: Estimating the Mass of Jupiter Difficulty: Medium OBJECTIVE The July / August observing notes for 010 state that Jupiter rises at dusk. The great planet is now starting its grand showing for

More information

ASTR 1030 Astronomy Lab 65 Celestial Motions CELESTIAL MOTIONS

ASTR 1030 Astronomy Lab 65 Celestial Motions CELESTIAL MOTIONS ASTR 1030 Astronomy Lab 65 Celestial Motions CELESTIAL MOTIONS SYNOPSIS: The objective of this lab is to become familiar with the apparent motions of the Sun, Moon, and stars in the Boulder sky. EQUIPMENT:

More information

Calculating Astronomical Unit from Venus Transit

Calculating Astronomical Unit from Venus Transit Calculating Astronomical Unit from Venus Transit A) Background 1) Parallaxes of the Sun (the horizontal parallaxes) By definition the parallaxes of the Sun is the angle β shown below: By trigonometry,

More information

lat/long/size&shape of Earth 1. Which statement provides the best evidence that Earth has a nearly spherical shape?

lat/long/size&shape of Earth 1. Which statement provides the best evidence that Earth has a nearly spherical shape? Name: Tuesday, September 23, 2008 lat/long/size&shape of Earth 1. Which statement provides the best evidence that Earth has a nearly spherical shape? 1. The Sun has a spherical shape. 3. Star trails photographed

More information

GOTOSTAR HAND CONTROLLER AND DUAL-AXIS DC SERVO-MOTOR DRIVER

GOTOSTAR HAND CONTROLLER AND DUAL-AXIS DC SERVO-MOTOR DRIVER GOTOSTAR HAND CONTROLLER AND DUAL-AXIS DC SERVO-MOTOR DRIVER The new GOTOSTAR hand controller and our specially designed dual-axis DC servomotor driver is our new patent product. The controlling accuracy

More information

SKINAKAS OBSERVATORY. Astronomy Projects for University Students PROJECT THE HERTZSPRUNG RUSSELL DIAGRAM

SKINAKAS OBSERVATORY. Astronomy Projects for University Students PROJECT THE HERTZSPRUNG RUSSELL DIAGRAM PROJECT 4 THE HERTZSPRUNG RUSSELL DIGRM Objective: The aim is to measure accurately the B and V magnitudes of several stars in the cluster, and plot them on a Colour Magnitude Diagram. The students will

More information

The Messier Objects As A Tool in Teaching Astronomy

The Messier Objects As A Tool in Teaching Astronomy The Messier Objects As A Tool in Teaching Astronomy Dr. Jesus Rodrigo F. Torres President, Rizal Technological University Individual Member, International Astronomical Union Chairman, Department of Astronomy,

More information

Artificial Satellites Earth & Sky

Artificial Satellites Earth & Sky Artificial Satellites Earth & Sky Name: Introduction In this lab, you will have the opportunity to find out when satellites may be visible from the RPI campus, and if any are visible during the activity,

More information

Motions of the Earth. Stuff everyone should know

Motions of the Earth. Stuff everyone should know Motions of the Earth Stuff everyone should know Earth Motions E W N W Noon E Why is there day and night? OR Why do the Sun and stars appear to move through the sky? Because the Earth rotates around its

More information

The Solar Journey: Modeling Features of the Local Bubble and Galactic Environment of the Sun

The Solar Journey: Modeling Features of the Local Bubble and Galactic Environment of the Sun The Solar Journey: Modeling Features of the Local Bubble and Galactic Environment of the Sun P.C. Frisch and A.J. Hanson Department of Astronomy and Astrophysics University of Chicago and Computer Science

More information

AST 114 Spring 2016 Introduction to the Night Sky INTRODUCTION TO THE NIGHT SKY

AST 114 Spring 2016 Introduction to the Night Sky INTRODUCTION TO THE NIGHT SKY NAME: INTRODUCTION TO THE NIGHT SKY What will you learn in this Lab? This lab will introduce you to the layout of the night sky: constellations and stars, their names and the patterns they make, and the

More information

Astronomy 1140 Quiz 1 Review

Astronomy 1140 Quiz 1 Review Astronomy 1140 Quiz 1 Review Prof. Pradhan September 15, 2015 What is Science? 1. Explain the difference between astronomy and astrology. (a) Astrology: nonscience using zodiac sign to predict the future/personality

More information

Motions of Earth LEARNING GOALS

Motions of Earth LEARNING GOALS 2 Patterns in the Sky Motions of Earth The stars first found a special place in legend and mythology as the realm of gods and goddesses, holding sway over the lives of humankind. From these legends and

More information

Night Observing Project I OBSERVING THE NIGHT SKY THE CONSTELLATIONS

Night Observing Project I OBSERVING THE NIGHT SKY THE CONSTELLATIONS Night Lab #1 Page 1 Night Observing Project I OBSERVING THE NIGHT SKY THE CONSTELLATIONS Note - bring a pencil, eraser, a star chart/wheel/planisphere, and this exercise packet. A. Objectives Learn to

More information

Unit 1: Understanding the Universe

Unit 1: Understanding the Universe Write your name here Surname Other names Edexcel GCSE Centre Number Astronomy Unit 1: Understanding the Universe Candidate Number Wednesday 15 May 2013 Afternoon Time: 2 hours You must have: Calculator,

More information

Vector Notation: AB represents the vector from point A to point B on a graph. The vector can be computed by B A.

Vector Notation: AB represents the vector from point A to point B on a graph. The vector can be computed by B A. 1 Linear Transformations Prepared by: Robin Michelle King A transformation of an object is a change in position or dimension (or both) of the object. The resulting object after the transformation is called

More information

Stellar, solar, and lunar demonstrators

Stellar, solar, and lunar demonstrators Stellar, solar, and lunar demonstrators Rosa M. Ros, Francis Berthomieu International Astronomical Union, Technical University of Catalonia (Barcelona, España), CLEA (Nice, France) Summary This worksheet

More information

SCIENCE 101 DISTANCES IN ASTRONOMY LECTURE NOTES

SCIENCE 101 DISTANCES IN ASTRONOMY LECTURE NOTES SCIENCE 0 DISTANCES IN ASTRONOMY LECTURE NOTES Distances in the Solar System Distance to Venus can be obtained using radar ranging Send signal, determine how long it takes to return Radio waves move at

More information

1.7 Cylindrical and Spherical Coordinates

1.7 Cylindrical and Spherical Coordinates 56 CHAPTER 1. VECTORS AND THE GEOMETRY OF SPACE 1.7 Cylindrical and Spherical Coordinates 1.7.1 Review: Polar Coordinates The polar coordinate system is a two-dimensional coordinate system in which the

More information

Renewable Energy. Solar Power. Courseware Sample 86352-F0

Renewable Energy. Solar Power. Courseware Sample 86352-F0 Renewable Energy Solar Power Courseware Sample 86352-F0 A RENEWABLE ENERGY SOLAR POWER Courseware Sample by the staff of Lab-Volt Ltd. Copyright 2009 Lab-Volt Ltd. All rights reserved. No part of this

More information

Paper Airplanes & Scientific Methods

Paper Airplanes & Scientific Methods Paper Airplanes 1 Name Paper Airplanes & Scientific Methods Scientific Inquiry refers to the many different ways in which scientists investigate the world. Scientific investigations are done to answer

More information

165 points. Name Date Period. Column B a. Cepheid variables b. luminosity c. RR Lyrae variables d. Sagittarius e. variable stars

165 points. Name Date Period. Column B a. Cepheid variables b. luminosity c. RR Lyrae variables d. Sagittarius e. variable stars Name Date Period 30 GALAXIES AND THE UNIVERSE SECTION 30.1 The Milky Way Galaxy In your textbook, read about discovering the Milky Way. (20 points) For each item in Column A, write the letter of the matching

More information

Optical Illusions Essay Angela Wall EMAT 6690

Optical Illusions Essay Angela Wall EMAT 6690 Optical Illusions Essay Angela Wall EMAT 6690! Optical illusions are images that are visually perceived differently than how they actually appear in reality. These images can be very entertaining, but

More information

Populations and Components of the Milky Way

Populations and Components of the Milky Way Chapter 2 Populations and Components of the Milky Way Our perspective from within the Milky Way gives us an opportunity to study a disk galaxy in detail. At the same time, it s not always easy to relate

More information

The Sun. Solar radiation (Sun Earth-Relationships) The Sun. The Sun. Our Sun

The Sun. Solar radiation (Sun Earth-Relationships) The Sun. The Sun. Our Sun The Sun Solar Factoids (I) The sun, a medium-size star in the milky way galaxy, consisting of about 300 billion stars. (Sun Earth-Relationships) A gaseous sphere of radius about 695 500 km (about 109 times

More information

Chapter 1: Our Place in the Universe. 2005 Pearson Education Inc., publishing as Addison-Wesley

Chapter 1: Our Place in the Universe. 2005 Pearson Education Inc., publishing as Addison-Wesley Chapter 1: Our Place in the Universe Topics Our modern view of the universe The scale of the universe Cinema graphic tour of the local universe Spaceship earth 1.1 A Modern View of the Universe Our goals

More information

Dance of Earth and Moon

Dance of Earth and Moon Science Benchmark: 03 : 01 Earth orbits around the sun, and the moon orbits around Earth. Earth is spherical in shape and rotates on its axis to produce the night and day cycle. To people on Earth, this

More information

Latitude and Longitudes in Geodesy James R. Clynch February 2006

Latitude and Longitudes in Geodesy James R. Clynch February 2006 Latitude and Longitudes in Geodesy James R. Clynch February 2006 I. Latitude and Longitude on Spherical Earth Latitude and longitude are the grid lines you see on globes. For a spherical earth these are

More information