Deep Space Explorer User's Guide


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Deep Space Explorer User's Guide

  2. 2. Canada Inc. 284 Richmond St. E. Suite 300 Toronto, ON M5A 1P4, Canada ©1993-2001 Canada, Inc. All rights reserved. and the logo are trademarks of, Inc. Deep Space Explorer, Starry Night, and the Starry Night logo are trademarks of Canada, Inc. Microsoft and Windows are trademarks of Microsoft. Apple, Macintosh, and QuickTime are registered trademarks of Apple Computer, Inc. Special thanks to Luke Kilpatrick for images on page 13 and page 32 and to Brent Tully for help in writing parts of chapter 4, “The Tully Collection”. Printed in Canada.
  3. 3. Table of Contents Introduction Welcome ................................................ 5 Outline Of This User’s Guide .................... 6 Special Fonts .......................................... 6 Installation ............................................. 7 Starting Deep Space Explorer ................... 8 Registering ............................................. 8 Updates .................................................. 8 Getting Help ........................................... 9 Starry Night Products .............................. 9 Basics Where am I? ......................................... 11 Heads-Up Display .................................. 11 Moving Around ...................................... 13 Elevation Buttons .................................. 13 Location Scroller ................................... 15 Returning Home .................................... 15 Location Exercises ................................. 15 Concentric Spheres ............................... 17 Navigation Bar ...................................... 17 Viewing Movies ..................................... 18 Media Player Controls ............................ 20 Exploring .............................................. 20 Objects Types of Objects ................................... 21 Finding Objects ..................................... 22 Getting Information ............................... 22 Onscreen Info (Galaxies) ....................... 24
  4. 4. 4 Deep Space Explorer User’s Guide Onscreen Info (Stars) ............................ 26 Onscreen Info (Extrasolar Planets) ......... 27 Internet Database ................................. 28 The Tully Collection Galaxy Distance .................................... 29 What’s In And What’s Out ...................... 30 Supergalactic Co-ordinates ..................... 31 Co-ordinate System Guides .................... 32 Groups and Filaments ............................ 33 Extragalactic Structure ........................... 34 Altering the Look Galaxy Drawing Options ......................... 37 Labels .................................................. 39 Creating Multimedia Files ..................................................... 41 Images ................................................. 42 Making Movies ...................................... 43 Spaceship Mode Piloting the Spaceship ............................ 48 Spaceship Tips & Tricks ......................... 49 Glossary...............................................51 FAQ QuickTime ............................................ 53 Registration Number ............................. 54 Installation Problems ............................. 55 Updates/Upgrades ................................. 55 General Run-Time Problems ................... 55 Internet Database ................................. 56 Multimedia ............................................ 57 Stars .................................................... 58 Index.....................................................59
  5. 5. Chapter 1 Introduction Welcome Welcome to Deep Space Explorer, the perfect tool for discovering the wonders of our universe. Deep Space Explorer will help you learn about the structure of our universe and the many strange and amazing creatures it contains, from glowing galaxies to the dark centers of black holes. No more are you trapped on Earth, seeing only those few stars and galaxies in our local neighbourhood. With Deep Space Explorer, you can leave the cradle of humanity behind and rocket through our solar system, into the heart of the Milky Way galaxy, and even farther into the dark reaches of intergalactic space. You can put yourself at the helm of a mighty starship, navigating through the universe faster than the speed of light. Thank you for purchasing Deep Space Explorer. Enjoy the program!
  6. 6. 6 Deep Space Explorer User’s Guide Outline Of This User’s Guide Space Explorer which simulates piloting a spaceship. All users of Deep Space Explorer should read chapters 1 and 2 of this User’s Guide Appendix A: “Glossary” defines some of to get a basic grasp of how to use the the specialized terms used in this User’s program. After this, you may want to Guide. explore on your own and only refer to the User’s Guide if you have questions about a Appendix B: “FAQ” is a list of the specific feature, or you may wish to read questions most commonly asked by users the entire User’s Guide cover to cover. of Deep Space Explorer and answers to Below is a brief summary of each chapter these questions. in the User’s Guide. Chapter 1: “Introduction” tells you how to Special Fonts get Deep Space Explorer up and running Three special fonts are used throughout for the first time. the text: Chapter 2: “Basics” covers the most 1) Command Font: This font is used to important features in the program. indicate a button, keystroke, or menu Chapter 3: “Objects” describes the choice. different types of celestial bodies included Example: Click the Home button to restore in Deep Space Explorer and the your default settings. information you can learn about each body. 2) File Font: This font indicates a folder or file, either on your hard drive or Chapter 4: “The Tully Collection” goes the Deep Space Explorer CD. File and into more detail about the new galaxy folder names are always enclosed in database at the heart of Deep Space quotations. Explorer and how you can use this database to study the large-scale structure Example: Locate the “Manual.pdf” file of our universe. on the CD. Chapter 5: “Altering the Look” shows you 3) Glossary font: A word displayed in this how to modify the look of Deep Space font is defined in the “Glossary” on Explorer to suit your own taste. page 51. Chapter 6: “Creating Multimedia” shows Example: One of the more common how save files and make videos and galaxy types is the elliptical galaxy. images using Deep Space Explorer. Chapter 7: “Spaceship Mode” describes the controls for the special mode in Deep
  7. 7. Introduction 7 Installation Explorer will not work unless you choose this option. At some point in the To run Deep Space Explorer, you need to installation, you may also be asked if install two programs: Deep Space you want to register QuickTime Pro. Explorer and QuickTime. If you already This is a more advanced version of have QuickTime 5.0.2 or later on your QuickTime not included with Deep computer, you do not need to install it Space Explorer. Leave this window again. To install Deep Space Explorer and completely blank and hit the Next QuickTime, follow the installation button to continue installing the regular instructions below. version of QuickTime. If you encounter Windows: an error message when installing QuickTime, please see “QuickTime” 1 Insert the compact disc in the CD-ROM on page 53. Once you have drive. A window will pop up onscreen successfully installed QuickTime, with the options “Install QuickTime 4” proceed to step 3. and “Install Deep Space Explorer”. 3 Choose “Install Deep Space Explorer” from the onscreen menu and follow the instructions that appear. If you encounter problems, please see “Installation Problems” on page 55. A successful installation will place a Deep Space Explorer icon on your desktop. Macintosh: 1 Insert the compact disk into the CD- ROM drive. 2 Open the “Read Me First” file for instructions and late-breaking product and compatibility information. 3 Drag the “Deep Space Explorer” folder from the CD to your hard disk. 2 Choose “Install QuickTime 4” from the onscreen menu and follow the instructions that appear. You will be asked to select an installation option for QuickTime. Make sure that you choose the “Recommended Install” option! Certain features in Deep Space
  8. 8. 8 Deep Space Explorer User’s Guide Starting Deep Space Explorer Otherwise, you can complete and return the registration form to us. Once you have installed Deep Space Explorer, you can start it as follows: Registering makes it possible for us to Windows: Double-click the Deep Space notify you of any upgrades, bug fixes, or Explorer icon on your desktop or click the plug-ins as they become available. You Start button on your desktop and then may also be eligible for reduced prices on choose other space and astronomy programs Programs->Deep Space Explorer->Deep written by If you ever need Space Explorer. to change any of your registration information, visit Macintosh: Double-click the Deep Space Explorer icon in the “Deep Space Explorer” folder. Updates Registering To make sure you have the latest version of Deep Space Explorer, you can choose A unique registration number for your Help->Check For Updates from the Deep copy of Deep Space Explorer is printed on Space Explorer menu. This will take you the last inside page of this User’s Guide. to the “Updates” section of our website. When you run Deep Space Explorer for the first time, you will need to enter this number to open the program. You should also register your copy of Deep Space Explorer with If you have Internet access, just click the Register Online button to do this.
  9. 9. Introduction 9 Getting Help Starry Night Products An electronic version of this User’s Guide Deep Space Explorer is only one in a line was installed on your computer when you of astronomy products made by installed Deep Space Explorer. You can We also produce the Starry access this User’s Guide by choosing Night family of astronomy software Help->Manual from the menu. products, which are designed to help you with stargazing and ground-based If you have technical questions which are astronomy. More information on these not answered in this manual, please check products is available at our website, our online Deep Space Explorer technical support FAQ by choosing Help->On-line Help from the menu. If you still have questions, e-mail us at
  10. 10. 10 Deep Space Explorer User’s Guide
  11. 11. Chapter 2 Basics Where am I? When you start Deep Space Explorer, you will see a black sky filled with points of light. Each one of those points is a galaxy, made up of billions of stars. The bright spiral galaxy directly in front of you? That’s our own Milky Way. Your starting point in Deep Space Explorer is just outside the Milky Way, 700 000 light years from home. Your distance from the sun is always shown along the bottom of the screen. Look closely and you will see that a few other galaxies also appear as detailed images, not dots. These are relatively nearby galaxies. Read on to learn how to move around this strange new world. Heads-Up Display Point the mouse at any object you see onscreen. This activates Deep Space Explorer’s Heads-up Display (HUD). You can use the HUD at any time to identify an object. Three pieces of information will come up. Object Name: The name of the object. Usually this name will be the object’s number in an astronomical catalog. However, if you are
  12. 12. 12 Deep Space Explorer User’s Guide pointing at a star, planet or named galaxy, Earth than star B, making it appear these will be identified by name. brighter. If we were located on an extrasolar planet orbiting Polaris, star B Magnitude: An object’s magnitude is a might have the lower apparent magnitude measure of its brightness. The confusing and appear brighter than star A. thing is that the brighter an object is, the lower its magnitude is. An object with Planets within our solar system do not magnitude -5 is much brighter than an have a fixed apparent magnitude (as seen object with magnitude 0, which is much from Earth). This is because the brightness brighter than an object with magnitude 5. of these planets changes as the planets Magnitude is calculated differently for move around the sun. Instead of the galaxies, planets and stars. apparent magnitude as seen from Earth, Deep Space Explorer shows you the For galaxies, Deep Space Explorer shows apparent magnitude as seen from your the absolute magnitude, which is a current position. As you move closer to the measure of the galaxy’s intrinsic planet, its apparent magnitude will brightness. The largest galaxies (including decrease, meaning that it is getting our Milky Way) have magnitudes -21 or brighter. As you move away from the -22. The smallest dwarf galaxies have planet and it gets dimmer, its apparent magnitudes of around -10. There is a magnitude will increase. complete range of galaxy magnitudes between these extremes. Distance: How far away you are from this object. This piece of information is For stars in our Milky Way, Deep Space dynamic- as you travel around in space Explorer shows the apparent magnitude and move closer to or farther away from (as seen from Earth). This compares the the object, its distance will change. You brightness of stars as seen from Earth. The may be unfamiliar with some of the brightest star in our sky is Sirius, which distance units: AU, LY, MLY. See has an apparent magnitude of -1.47. Any “Distances from Sun” on page 14 for star that has an apparent magnitude less definitions of these units. The distance to than 6 will be visible from Earth on a dark galaxies is not easy to measure. See night without the use of binoculars or a “Galaxy Distance” on page 29 to learn telescope. The key difference betwen how we measure these distances. apparent magnitude and absolute magnitude is that apparent magnitude depends on your location. If galaxy A has a lower absolute magnitude than galaxy B, we can say with certainty that galaxy A is intrinsically brighter than galaxy B. On the other hand, if star A has a lower apparent magnitude (as seen from Earth) than star B, it may be intrinsically brighter than star B, but it may not. It may just be closer to
  13. 13. Basics 13 Moving Around While your view of the Milky Way is very pretty, you didn’t buy Deep Space Explorer to look at a static image. You want to learn how to move about this magnificent universe of ours! There are three distinct tools for changing your location in Deep Space Explorer: 1 The Location Scroller tool. 2 The Elevation buttons. 3 The Spaceship button. Elevation Buttons Both the Location Scroller tool and the Elevation buttons adjust your position in These are the two buttons in the top left reference to a certain celestial object- this corner of your screen, immediately to the is the object you are centred on. By right of the Spaceship button. They control default, you are centred on the sun. In your elevation, which is the distance from “Getting Information” on page 22, you the object that you are centred on. will learn how to centre on a different Decrease Elevation object. Increase Elevation The elevation buttons change your distance from the centred object, while Each time you click one of these buttons, keeping your direction the same. The your elevation increases or decreases by location scroller tool does the opposite, 10 %. Test this out by clicking the Increase changing your direction, but keeping your Elevation button several times. The image distance from the object constant. One of the Milky Way should become smaller, way to think of this is to picture yourself at indicating that you are moving farther a point on the surface of an inflatable away from it. sphere, centered on the object. Using the Elevation buttons is like inflating or Your current elevation is always shown deflating the sphere, whereas using the along the bottom of the main screen. This Location Scroller tool is the equivalent of display updates when you use the moving around on the surface of the elevation buttons to increase or decrease sphere. your elevation.
  14. 14. 14 Deep Space Explorer User’s Guide Distances from Sun: Here are the For the distances to galaxies, even the light approximate distances of various objects year is not a large enough unit, so we use from the sun: mega light years, “MLY” for short. A mega light year is equal to one million light years. Name Distance from Sun Earth 1 AU Pluto 30 AU Nearest 4 LY Stars Center of 25 000 LY Milky Way Nearest 80 000 LY Galaxy Size of DSE 700 MLY dataset Edge of 13000 MLY Universe “AU” stands for astronomical unit, which is defined as the average distance between the earth and the sun. It is approximately 150 million kilometres (93 million miles). “LY” stands for light year, which is the distance that light travels in a year. Light travels at 300 thousand kilometres per second (186 thousand miles per second) so a light year is equal to this value multiplied by the number of seconds in a year. This is a huge number: 9.46 trillion kilometres (6 trillion miles).
  15. 15. Basics 15 Location Scroller In the same way that you have used the Location Scroller to rotate your view of To use the Location Scroller tool, just click the Milky Way, you will be able to rotate and hold on any area of the sky and then other galaxies, and the faces of individual move the mouse around. You will see your planets. view of the sky rotate in the direction that you moved the mouse. Returning Home Practice using the Location Scroller to rotate your view of the Milky Way. You Where is home in a product should be able to view the galaxy face-on, like Deep Space Explorer? edge-on, or any state between these two Pressing the Home button extremes. returns you to the view that you get when you open the program, 700 000 light years from Earth, looking back at the Milky Way. If you are ever lost, just press the Home button to return to this familiar view. Location Exercises These two exercises will help you practice changing your location using the Location Scroller and the Elevation buttons. Example 1: Viewing our Solar System 1 Press the Home button. 2 Press the Decrease Elevation button several times, until your elevation is reduced to about 50 000 light years. You will see that we are zooming in on a cluster of stars in one of the Milky Way’s spiral arms. These are the stars in the neighbourhood of our own sun.
  16. 16. 16 Deep Space Explorer User’s Guide 3 Continue pressing the Decrease the stars that you saw in example 1. Elevation button until your elevation is You will notice that the galaxies are not about 1 light year. The disk of the spread evenly throughout the sky, but Milky Way will disappear as you move are clustered into densely populated inside it. Stars will fly by as you patches and strings, separated by voids continue moving closer to the sun. with no galaxies at all. Eventually, you will see a small glowing halo at the center of your 3 Keep pressing the Increase Elevation screen. This is the sun. button until your elevation is about 800 MLY. You will see that the galaxies are 4 Continue pressing the Decrease collapsing into the center of the screen. Elevation button until your elevation is You have reached the edge of the about 40 AU. You will see a number of dataset in Deep Space Explorer. Use loops drawn onscreen. These loops are the Location Scroller tool to rotate your the orbits of the planets. Use the view of the dataset and examine its Location Scroller to rotate your view of structure. these orbits. You will see that all the orbits can line up in one plane, with the 4 Continue pressing the Increase exception of one. The oddball planet is Elevation button. You have passed Pluto. beyond the dataset used in Deep Space Explorer, and the outlying areas of the 5 Continue pressing the Decrease universe are represented by concentric Elevation button until your elevation is spheres. These spheres are described in about 3 AU. You should be able to see the next section. Once you have 4 complete loops onscreen. Arranged in reached 14 000 MLY, you have reached order from closest to the sun out to the edge of the universe, and can travel farthest from the sun, these orbits no farther! represent Mercury, Venus, Earth and Mars. 5 Press the Home button to return to your original view. 6 Press the Home button to return to your original view. Example 2: Going to the Universe’s Edge 1 Press the Home button. 2 Press the Increase Elevation button until your elevation is about 50 MLY. You are flying away from the Milky Way, and it will shrink into nothingness. As in example 1, you will see little dots flying by you. However, these dots are individual galaxies, not
  17. 17. Basics 17 Concentric Spheres these shapes evolved into the familiar spiral and elliptical galaxies that we see Once you move more than one billion light today. years from Earth, you are farther from Earth than any of the galaxies included in CMB (11 billion light years): The oldest Deep Space Explorer. Looking this far out thing in the universe that astronomers can into space is equivalent to looking back see is the cosmic microwave background into time. If we look at a galaxy which is (CMB). This is radiation that is left over 4.5 billion light years from Earth, we are from when the universe was only 1 million actually seeing this galaxy as it looked 4.5 years old. billion years ago, when our Earth was Big Bang (14 billion light years): Our born. Deep Space Explorer represents universe began in a fireball known as the these distant reaches of the universe with Big Bang. Astronomers believe that the four different concentric spheres. Big Bang took place between 13 and 15 billion years ago. It is impossible to know what (if anything) existed before the Big Bang. Navigation Bar Along the left side of the main Deep Space Explorer window you will see five panes. This is the Navigation Bar. Click on a pane to show the options for that pane, and click the same pane again to collapse the Navigation Bar to its Galaxy Clusters (2 billion light years): minimum size, with no options present. The panes are as follows: This shows the massive clusters of galaxies that lie outside the database. Views: Multimedia movies that explain These clusters bend the light from even different topics about our universe. There more distant objects, letting us see farther are 19 different movies, and over an hour back into space and time. of video in total. Described in “Viewing Movies” on page 18. Young Galaxies (6 billion light years): As we look far back into space and time, we Labels: Options for labelling different see young galaxies which are still forming. types of objects and changing the look of These galaxies often have unusual shapes. these labels. Described in “Labels” on Astronomers are trying to determine how page 39.
  18. 18. 18 Deep Space Explorer User’s Guide Guides: Grids and reference markers to To see a list of the help show your position in space. multimedia clips, Described in click the Views pane “Co-ordinate System Guides” on page 32. in the navigation bar. Aside from a few Settings: General settings affecting the introductory clips, look of the galaxies displayed in Deep the movies are sorted Space Explorer. Described in in order of increasing “Galaxy Drawing Options” on page 37. distance from earth, Highlights: Options for highlighting the beginning with different galactic groups and filaments. topics like satellites Described in and the moon, and “Extragalactic Structure” on page 34. progressing to galaxies, black holes, and even the Big Viewing Movies Bang. Over an hour of multimedia clips are included with Deep Space Explorer. Nineteen different clips explore topics that range across the entire field of astronomy, from satellites to black holes. These videos Click on any clip, and the DSE media will help you learn more about the player will automatically open and begin universe, and will increase your enjoyment playing the clip. See “Media Player of Deep Space Explorer. Each clip is Controls” on page 20 for more information narrated by actress Chase Masterson, and on the controls in the media player. many clips feature expert commentary by astronomer Brent Tully.
  19. 19. Basics 19 Tip: You will not be able to view these The Grand Architecture: Voids, filaments movies unless the Deep Space Explorer and other large-scale structures that appear CD is in the CD-ROM drive. To learn how in the Tully Collection. to move the movies to your hard drive, see This Matter of Matter:The mysterious “Multimedia” on page 57. dark matter that makes up 90% of our Below is a brief description of each of the universe. movie clips: Collision/Construction: How mighty Your Universe: An introduction to Deep galaxies smash together to create beautiful Space Explorer, from the perspective of an new forms. intergalactic explorer travelling through Edge of the Known: New astronomy space. research projects that will allow us to look Know Your Place... The different sizes and even farther into space. distances of the important objects that Yesterday’s News: How our universe was make up our universe. different in the early years. From Radar to Redshift: How we measure The Dark Force: The lesser-known the distances to planets, stars and galaxies. companion of dark matter, dark energy is Rivers in the Sky: The satellites that orbit repsonsible for the expansion of our our Earth. universe. The Way of Things: How our universe has Earth, Moon, Sun: the Perfect Ballet: The how and why of solar eclipses. evolved and will evolve in the future. Birth of the Family of Sol: The origins of Earth and other planets. Jewels and Junk: Asteroids, comets, and other strange bodies in our solar system. Extrasolar Planets: The strange new worlds we have discovered around other stars. Galaxy: Home: The structure of our home galaxy, the Milky Way. Black Holes: All about black holes. The Tully Collection: The database of galaxies at the heart of Deep Space Explorer. Galactic Lives: The different types of galaxies in our universe.
  20. 20. 20 Deep Space Explorer User’s Guide Media Player Controls Exploring Deep Space Explorer has a unique media You will notice that each section in the player, the controls of which are quite Views pane also has an “Explore” listing. straight-forward. Click the icon to the left of the word “Explore” (this is a ‘+’ sign on Windows, and an arrow on the Macintosh) and the list expands. Clicking on any item in this list will change your view to show something interesting in Deep Space Explorer. Each item in the “Explore” list is a Deep Space Explorer file, not a movie. You will learn more about Deep Space Explorer files in “Files” on page 41. The key point to understand now is that you can use any of the program controls to adjust your view and explore further. Tip: If the original media player does not close when you press the “Increase/ Decrease Viewer Size” button, you need to adjust your QuickTime Player preferences. Open the QuickTime Player (on Windows, you do this by clicking the Start button on your desktop and choosing Programs- >QuickTime->QuickTime Player). Choose Edit->Preferences->Player Preferences and check the box reading “Open movies in new players”.
  21. 21. Chapter 3 Objects Types of Objects You’re probably wondering exactly what celestial objects are included in Deep Space Explorer. They fall into three major categories. Planets: All 9 planets in our solar system (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto), as well as the Sun. In addition all the major moons of these planets are included, such as Io, Titan, and Europa. Stars: The 30 000 brightest stars in the night sky (as seen from Earth). Every star that you can see in the sky with the naked eye is included, plus many stars that can only be seen with binoculars or a telescope. Most of these stars are within a few hundred light years of the Sun, but a few are as far as two thousand light years away. The data on these stars comes from the Hipparcos catalogue, which is the result of a recent mission by the European Space Agency. This mission measured the distances to these stars more accurately than they had ever been measured before, which allows us to calculate their position in 3-D space. Galaxies: The heart of Deep Space Explorer is a database of 28 000 nearby galaxies. These galaxies span an area approximately 700 million light years wide. This database is described in detail in “The Tully Collection” on page 29.
  22. 22. 22 Deep Space Explorer User’s Guide Finding Objects Getting Information To find any of the objects mentioned You learned how to find some basic above, just choose Edit->Find from the information about an object using the menu and type in the name of the object HUD in “Heads-Up Display” on page 11. you want to find. You can search for a star To get more information, point the cursor or galaxy by its name or catalogue number. at an object (you should see the cursor icon change to a pointer) and then right- Tip: If searching for an object by its click (Windows) or Ctrl-click (Macintosh). catalogue number, make sure you type in This opens up a contextual menu with the catalogue code. For example, to find specific options for the object you have Messier object 87, you would type “M87”, clicked on. The options in this menu are not just “87”. described below. Then press the Find button, and Deep Space Explorer will pan around and center on the object for you. You can control the panning speed by adjusting the “Panning Speed” slider in the File->Preferences menu.The next section shows you how to find out more about any object. Select: Selecting an object turns on the HUD information for that object, and this information remains onscreen even when you move the cursor away from the object. It is possible to select multiple objects by holding down the Shift key while right- clicking on a second (or third, or fourth...) object and selecting that object. If you do not hold down the Shift key when doing this, objects that you have previously selected will be deselected. To deselect all objects, choose Edit->Select None from the menu.
  23. 23. Objects 23 Centre: Centring an object places it in the Go There: This option automatically middle of the screen and also causes this changes your location to the object you object to become the new base about clicked on. It achieves the same purpose as which you move using the Elevation centring on the object and using the buttons or the Location Scroller tool. In Decrease Elevation button until the object “Moving Around” on page 13, we learned fills the screen, but it does this in an that both the Location Scroller tool and the animated fashion, simulating a “flight” to Elevation buttons adjust your position in the new object. As you fly through space, reference to the object you are centred on. your current distance from the object will Remember that by default, you are centred be shown along the bottom of the screen, on the Sun. If you centre on the along with your distance from the sun. Andromeda Galaxy, using the Elevation Centre Group: Each galaxy belongs to a buttons now change your distance relative larger group of galaxies. You can learn to the Andromeda Galaxy, not the Sun. more about groups in When you are centred on an object other “Groups and Filaments” on page 33. This than the sun, the bottom of the main screen option will place that group at the center of displays both your distance from the sun your screen. and your distance from the object you are centred on. Tip: The “Centre Group”, “Highlight Group”, Centre Filament” and “Highlight The Centre command can be used together Filament” options are only available for with the Location Scroller tool and the galaxies, not planets or stars. Elevation buttons to show you close-up 3-dimensional views of any object in Deep Highlight Group: This displays a special Space Explorer, as shown in the following marker for all other galaxies that are in the example. same group as the object you have clicked on. Example 1: Viewing Jupiter Centre Filament: Many (but not all) 1 Choose Edit->Find from the menu and galaxies can also be classified as type in “Jupiter”, then press the Find belonging to a filament. You can learn button. This will centre on Jupiter. more about filaments in 2 Use the Decrease Elevation button to “Groups and Filaments” on page 33. This zoom in until Jupiter almost fills the option centres on the filament containing screen. your object. Highlight Filament: This displays a special 3 Use the Location Scroller to adjust your marker for all galaxies belonging to the view of Jupiter, so that you can move same filament as the object you have around and see all sides of the planet. clicked on. You will see that half of the planet is lit up by the sun, while the other half is in shadow.
  24. 24. 24 Deep Space Explorer User’s Guide Show/Hide Info: This displays more more prominent galaxy catalogues are the information about the object in the top left NGC (New General Catalogue), IC (Index corner. All of these information fields are Catalogue), and PGC (Principal Galaxy described in “Onscreen Info (Galaxies)” Catalogue). on page 24. If information is already Object Type: This field lists the galaxy displayed in the top left corner, clicking this option again hides the info. type according to the revised Hubble sequence of galaxies, which is a method of Online Info: This option allows you to classifying galaxies according to their age, search our Internet database for more amount of interstellar gas, and rate of star information about the object. See formation. There is a continuum of “Internet Database” on page 28 to learn possibilities between galaxies with no gas how to use the Internet database. and only old stars at one extreme, and galaxies with lots of gas and a dominant component of young stars at the other Onscreen Info (Galaxies) extreme. You are probably familiar with Choosing Show Info from an object’s the difference between spiral and elliptical contextual menu displays information in galaxies, but there are 18 different galaxy the top left corner of the screen. The types. information shown is different for stars and galaxies. Elliptical galaxies have only very old stars and no interstellar gas or star formation regions. They are puffed up into rugby ball or helium balloon shapes. We can subdivide elliptical galaxies farther by how round they are. E- galaxies are almost perfectly spherical, whereas E+ galaxies are quite flattened. E0 galaxies are somewhere in-between. M87, the giant elliptical at the heart of the Virgo Cluster, is a classic example of an elliptical galaxy. Lenticular galaxies are a transition type between elliptical and spiral galaxies. For galaxies, the following information is They have a barely detectable disk, but displayed (in addition to the object’s otherwise resemble elliptical galaxies. magnitude and distance, which you Lenticular galaxies were forming new already now about): stars until quite recently. Lenticular galaxies are also known as S0 galaxies, Catalogue number: Most galaxies do not and we can subdivide them (in order of have a proper name, but are instead identified by their position in one or more increasing disk visibility) into S0-, S00, astronomical catalogues. Some of the
  25. 25. Objects 25 S0+, and S0a. Messier object M85 is a Im (some hints of structure) and I0 (no lenticular galaxy. structure at all). As with Sd and Sm galaxies, irregulars tend to be smaller Spiral galaxies are big galaxies with lots galaxies where gravity has not bound the of interstellar gas and star formation galaxy into a recognizable spiral pattern. regions. The gravitational force of billions Supergalactic X, Y, Z Co-ordinates: These of stars makes the galaxy rotate and three values define a galaxy’s position in flattens it into a thin disk which surrounds the supergalactic co-ordinate system, a central bulge. This disk contains bright explained in “Supergalactic Co-ordinates” spiral arms, where interstellar gas is on page 31. You can use an object’s compressed to form new stars. We can supergalactic co-ordinates to determine its subdivide spiral galaxies by the relative position in relation to the earth and sun. size of the central bulge and the tightness of the central arms. Sa galaxies (such as Galaxy Diameter/Thickness: Diameter is M104, the Sombrero Galaxy) have very the length of the galaxy in the plane of its tightly wound spiral arms and a large spiral arms, and thickness is the length of central bulge. Sc galaxies (such as M51, the galaxy in the plane perpendicular to its the Whirlpool Galaxy) have loose spiral arms. You will find that the diameter and arms and a much smaller central bulge. thickness of elliptical galaxies are similar, Intermediate betwen Sa and Sc galaxies while spiral galaxies will have a diameter are types Sab, Sb and Sbc. Our own Milky much greater than their thickness. Way is an Sc galaxy. Group ID: The ID number of the larger Some smaller galaxies do not fit into any group to which the galaxy belongs. See of the above categories. The reason is that “Groups and Filaments” on page 33 for gravity is less powerful in smaller more on groups. galaxies, and the galaxy does not spin as Filament ID: The ID number of the larger rapidly, so it is not compressed into as filament to which the galaxy belongs. See well-defined a shape as the larger Sa, Sb “Groups and Filaments” on page 33 for and Sc spirals. We use the classifications more on filaments. Not every galaxy Scd, Sd, Sdm, and Sm (in order of belongs to a defined filamentary structure, decreasing spiral structure) for spiral so not all galaxies will have this option in irregular galaxies, galaxies without much their onscreen info. of a central bulge or well-defined central arms, but still some semblance of spiral structure. These galaxies have lots of gas and star formation. The Large Magellanic Cloud is an example of an Sdm galaxy. Finally, there are the irregular galaxies, which show almost no spiral structure and have lots of “lumps” where star formation is occurring. We subdivide irregulars into
  26. 26. 26 Deep Space Explorer User’s Guide Onscreen Info (Stars) is on the reddish side of the spectrum. The more negative or positive a star’s B-V The info displayed onscreen when you value, the more blue or red it will appear. choose Show Info from a star’s contextual A star’s colour is directly related to its menu is quite different than the temperature: blue stars are hotter and red information shown for galaxies. stars are cooler. TYC number: The star’s number in the Tycho star catalogue. Variability: This indicates whether a star’s apparent magnitude (and, therefore, its brightness) varies with time, and by how much. Proper Motion: Stars are not fixed in space, and most are in fact moving quite rapidly. Because of their great distance from us, however, their positions appear For stars, the following fields are shown constant. Only on a timescale of hundreds (in addition to the object’s magnitude and or even thousands of years can we actually distance, which you already now about): see their position shift as seen from Earth. These fields describe how much the star’s HIP number: The star’s number in the earth-based co-ordinates are shifting each HIPPARCOS star catalogue. year due to the star’s movement. Bayer: The star’s Bayer catalog letter, if Temperature: This is the star’s surface any. The Bayer letter is from the Greek temperature, given in degrees Kelvin (to alphabet. The brightest star in a given get a star’s temperature in Celsius, just constellation is named Alpha (the first subtract 273 from its temperature in letter in the Greek alphabet), the second Kelvins). The sun has a temperature of brightest is named Beta, and so on. about 5700 K. Flamsteed/other: This gives the star’s Luminosity: Luminosity measures the light Flamsteed number, if any. The Flamsteed output of a star, in comparison with the system orders stars not by brightness, but sun. by their position relative to the western boundary of the constellation they are in. Absolute magnitude: Another method of The star closest to the constellation’s quantifying the light output of a star, and western edge is labelled 1. therefore its intrinsic brightness. The lower the absolute magnitude, the brighter B-V colour: This is a way of measuring a the star. You will note that all stars have star’s colour. An average star has a B-V absolute magnitudes much larger than value of around 0. If a star has a negative even the smallest galaxy, indicating that B-V value it is on the bluish side of the spectrum. If it has a positive B-V value it
  27. 27. Objects 27 every galaxy is intrinsically much brighter orbit with eccentricity close to 1 is than a star. extremely stretched out. Radius: This measures the star’s radius, in Inclination: how much the orbit is tilted, terms of the sun’s radius. Red giant stars relative to our view from Earth. An can be hundreds of times larger than the inclination of 0 means that we are seeing sun. the orbit edge-on, and an inclination of 90 means that we are seeing the orbit face-on. Double/multiple: This field indicates whether a star is part of a multiple star Radius: the size of the planet, again system. About half the stars in the sky are relative to Jupiter. part of a multiple star system. Note: Some stars have more than one extrasolar planet. If this is the case, the Onscreen Info (Extrasolar star’s onscreen info shows the info for the Planets) largest extrasolar planet. Certain stars in Deep Space Explorer are special because they contain their own planets. See “Show Extrasolar planets” on page 39 to learn how to identify these special stars. If you choose Show Info for a star that has extrasolar planets, you will see a few pieces of additional information: Mass: the mass of the extrasolar planet. All the extrasolar planets discovered to date have been very heavy, so masses are given in terms of Jupiter masses, not Earth masses. Semi-major axis: the average distance of the planet from its star. Distances are given in astronomical units (remember that 1 AU is the distance from Earth to the sun). You will find that most extrasolar planets are much closer to their parent star than Earth is to the sun. Period: the time that it takes the extrasolar planet to revolve once around its parent star. Eccentricity: eccentricity measures how close an orbit is to a circle. An orbit with eccentricity 0 is perfectly circular, and an
  28. 28. 28 Deep Space Explorer User’s Guide Internet Database Some of the links in our Internet database will appear for all objects (these may be Selecting Online Info from an object’s changed if better sources become contextual menu brings up a page on our available). These links are described Internet database which has a listing of below. web links which have more information about the object. The left side of the page Digitized Sky Survey: The Digitized Sky will also give you the option of searching Survey (DSS) is a collection of images other sites on the Internet, both general- obtained with two Schmidt telescopes and purpose search engines and astronomy- converted into digital format by the Space specific pages, for information on your Telescope Science Institute. The digitized object. data allows the user to generate an image of any area in the sky. Clicking this link on our webpage will automatically generate a DSS image of the object you originally clicked on in Deep Space Explorer. HEASARC Astrobrowse: Clicking this link will search dozens of astronomy databases for information on your object. A new window will open with each database being searched listed on the left side. When the search for that database has been completed, a green “happy-face” icon will appear beside the name of the database. You can then click the name of the database to retrieve the information. Example 2: Finding Web Pages for the Moon 1 Choose Edit->Find and type in “moon” to center on the moon. 2 Right-click or Ctrl-click on the moon and choose Online Info from the contextual menu. At this point your browser should go to our Internet database and retrieve a page that contains several links to places on the Internet with more information about the Moon. Click on any of these links to read interesting facts and trivia about the Moon, and to see lots of pictures and figures.
  29. 29. Chapter 4 The Tully Collection The heart of Deep Space Explorer is a 3-D database of 28 000 nearby galaxies. This database was compiled by astronomer Brent Tully and colleagues, hence it is referred to in this guide as the Tully Collection. This chapter describes how you can use the controls of Deep Space Explorer to organize and make sense of this database. Galaxy Distance The galaxy database in Deep Space Explorer is very special because it shows the 3-D position in space of each galaxy, not just the galaxy’s position as seen from Earth. To convert a galaxy’s apparent position in our night sky into a 3-D position, we need to know the distance to the galaxy. This can be calculated by measuring the light that comes from a galaxy. Galaxies which are moving toward us will produce a light curve that is slightly bluer than usual, while galaxies moving away from us will be slightly redder. This phenomenon is known as the Doppler shift, and the specific case of objects appearing redder because they are moving away from us is known as “redshift”. Scientists can calculate the speed of any galaxy in this way. With the exception of a few galaxies close to our Milky Way, we find that ALL galaxies are red-shifted, which means they are moving away from us. The reason behind this is the overall expansion of the universe,
  30. 30. 30 Deep Space Explorer User’s Guide everything moving away from everything else. In fact, the faster a galaxy is moving away from us, the farther away it is. For every million light years of distance, a galaxy will move away from us 23 kilometres/second faster. So a galaxy 10 million years distant moves away from us at a speed of 230 kilometres/second, while a galaxy twice as far away moves twice as fast, 460 kilometres/second. We can use this technique to measure the distance to galaxies. What’s In And What’s Out Even within this volume there are serious The 28 000 galaxies in Deep Space aspects of incompleteness. The most Explorer are only an infinitesmal fraction obvious is the bite taken out of the data in of those known to exist in our universe. the plane of our Milky Way. Thick dust How did we decide what to put in the regions in the plane of the Milky Way database and what to leave out? The block the light from distant galaxies. database of galaxies fills a box with Radio waves and x-rays can penetrate dimensions of 700 million light years on these dust regions more easily than visible each side, with Earth at the center. light, so new research programs using Galaxies inside this volume were included these methods are having some success in the database, and more distant galaxies locating galaxies along the plane of the outside the boundaries were left out. The Milky Way. However, there is still a gap of boundary was chosen because, frankly, at about 10 degrees coincident with the larger distances our ignorance is too great. Galactic plane where there is almost no Currently, information exists in only information about the universe beyond our selected patches about the distribution of galaxy. distant galaxies. In most directions, current surveys become very incomplete There is a second obvious incompleteness beyond the boundary of the volume in the data. Only those galaxies which are explored here. In Deep Space Explorer, bright enought to be seen and measured you can turn on a bounding box for the from earth can be included in the database. Tully Collection by checking the option A galaxy’s brightness depends on two “Show bounding box around entire things: how much light it emits (known as dataset” in the Guides pane. intrinsic luminosity) and how far away it is from Earth. The intrinsic luminosity of galaxies varies by a factor of ten thousand or more, from tiny dwarfs with only a few million stars to giant ellipticals 100 times
  31. 31. The Tully Collection 31 larger than our Milky Way. Obviously, Supergalactic Co-ordinates these giant ellipticals can be much farther away from earth and still be visible. Tiny So how can we define an object’s 3- dwarfs are only visible if they are very dimensional position within the Tully nearby, intermediate brightness galaxies Collection? Deep Space Explorer uses a are included to intermediate distances, and special supergalactic co-ordinate system giant galaxies are included to the distance for this purpose. It turns out that a large boundary of the data base. This sampling fraction of the nearest few thousand artifact explains why the database includes galaxies are concentratred in a narrow lots of dwarf galaxies in our vicinity but band, as seen from Earth. We define the few at large distances. center of this band as the supergalactic equator. Example 1: Viewing the Tully Collection We can then define 3 co-ordinates in 1 Press the Home button relation to this equator: supergalactic X, supergalactic Y, and supergalactic Z. 2 Use the Increase Elevation button to These co-ordinates usually have units of blast off until you are about 800 MLY mega light years (MLY). The co-ordinates above the sun. You should see the of galaxies relatively close to Earth are dataset begin to collapse into a box-like sometimes given in units of light years shape. (ly). Remember that one MLY equals one 3 Turn on the boundaries of this box by million ly. The supergalactic X and opening the Guides pane and checking supergalactic Y axes are both in the plane the box that reads “Show bounding box of the supergalactic equator (and around entire dataset”. This will show perpendicular to each other), while the you the exact edge of the Tully supergalactic Z axis is perpendicular to collection. this plane. 4 Use the Location Scroller tool to rotate your view of the Tully collection. You should see a slice through the middle of the bounding box that contains very few galaxies. This is the plane of the Milky Way, where we have been unable to identify many galaxies due to obscuration of the distant galaxies by dust.
  32. 32. 32 Deep Space Explorer User’s Guide of galaxies near the supergalactic equator. For example, the spiral Triangulum galaxy has supergalactic X,Y,Z, co-ordinates of (2.372,-1.456,0.004). Because the Z value is much smaller than the X and Y values, the Triangulum galaxy is almost exactly along the supergalactic equator. On the other hand, galaxies with large supergalactic Z values (relative to their supergalactic X and Y values) are far from the supergalactic equator. Co-ordinate System Guides You can find the position of any galaxy relative to the supergalactic So what do a galaxy’s supergalactic co- co-ordinate system ordinates tell us? Two key things: its using the options in distance from the sun, and its position the Guides pane. relative to the supergalactic equator. Check the box “Show grid and Galaxies with large supergalactic X, Y or axis labels” at the Z values are far from the sun, while bottom of this pane objects with small values are relatively to turn on the labels nearby. For example, the supergalactic for any of the co-ordinates of the Large Magellanic guides. Cloud (in units of MLY) are (-0.117, - 0.084, -0.098) while the supergalactic co- Tip: The supergalactic co-ordinate system ordinates of NGC 2484 are is centred on the sun, and you therefore (343.7, 305.6, -315.7). We can predict that need to be near the sun for the information NGC 2484 is much farther away from us from the guides in the Guides pane to be than the Large Magellanic Cloud, and this meaningful. When you want to use any of is indeed the case. The Large Magellanic these guides to find a galaxy’s position in Cloud is one of our nearest neighbours, at the supergalactic co-ordinate system, first a distance of 0.174 MLY. Compare this press the Home button to place yourself with NGC 248, which is at the edge of the above the Milky Way, and then use the Tully dataset, 557.9 MLY from the sun. Decrease Elevation button to lower yourself until you are within a few Objects with large supergalactic X and/or thousand light years of the sun. Y values (relative to their supergalactic Z values) are in the densely populated band
  33. 33. The Tully Collection 33 Equator, Meridian, Poles: These Auto drop references: If you have turned checkboxes turn on/off the supergalactic on the “large” reference axes, “auto drop” equator, meridian and poles, respectively. marks the 3-D position of the brightest The meridian is a line perpendicular to the three objects in the sky, relative to both the equator. If you turn these guides on when object you are centred on and the you are inside the Milky Way, you will supergalactic equator. If you select an find that the disk of the Milky Way (the object by right-clicking on it, its 3-D area of space where you see many bright position will also be marked. stars and a central bulge) is almost parallel to the supergalactic meridian (about 6 degrees away from parallel). If you click Groups and Filaments on the “Colour” bar in this section of the When you looked at the entire Tully Guides pane, you can change the colour of collection in these guides. “Viewing the Tully Collection” on Background Grid: This option draws a page 31, you probably noticed that the complete supergalactic grid, letting you galaxies were not randomly distributed see the poles, equator and other lines of throughout the cube, but formed patterns latitude and longitude. The “spacing” of clumps, strings, walls and voids. This is option controls how wide the spacing is evidence that galaxies are only between the lines of latitude and longitude components of even larger structures. We on the grid. You can choose from one of split these structures into two major three settings: fine, medium or coarse. divisions: groups and filaments. Clicking the “colour” rectangle lets you change the colour of the supergalactic Groups are gravitationally bound clumps grid. of galaxies. Membership can range from a few to a few thousand galaxies. Large Reference Axes: Use these controls to see groups are also known as clusters. how your current onscreen view of space is oriented with respect to the Filaments - or their kin walls, clouds, and supergalactic co-ordinate system. The arcs - are formations of galaxies in “small” option draws the three expanding space, which are not supergalactic co-ordinate axes in the upper necessarily gravitationally bound. These right corner (x in green, y in yellow, z in formations can be string-like or sheet-like. red). The “large” option draws a grid at the They can have curvature like a bow or like center of the screen representing the a sail. Filaments can be grouped together supergalactic equatorial plane, with the into even larger structures called filament three co-ordinate axes protruding from the families. center of the grid. The grid is always centred on the object that you are currently Groups and filaments are intimately centred on. Clicking the “Plane Colour” connected. Clusters - big groups - tend to rectangle lets you change the colour of the lie at nodes where filaments meet. The grid. filaments form a three-dimensional roadway connecting the urban centers of
  34. 34. 34 Deep Space Explorer User’s Guide the clusters and are dotted with village Extragalactic Structure groups. Some walls and arcs are wide expressways. Some filaments degenerate There are many filaments, walls, groups, into lanes or paths. Essentially all clusters, and voids to be explored in the filaments do connect to other filaments so Tully Collection. The principal tool for it is false to say that `you can't get there exploring these structural elements is the from here'. Between the filaments lie great Highlight pane in the navigation bar. The voids, regions of space millions of light pull-down menu lets you examine the years across that are empty of galaxies. database by one of five methods: filament family, filament name, filament ID, group A galaxy can belong to at most one group ID and galaxy type. and at most one filament. You can examine the group or filament to which Choosing any of any galaxy belongs by right-clicking on these categories will the galaxy and choosing Highlight ”xxx” display a list of all group or Highlight “xxx” filament. This will objects in the highlight all galaxies belonging to that category. You can group or filament. click on any object in the list to Note: if a galaxy does not belong to a highlight that group or filament, these options will not object. If you have appear in its contextual menu. “Show bounding box” checked, all The next section explains how we can use highlighted groups, groups and filaments to explore the large- filaments or scale structure of the Tully Collection. families, will be surrounded by a 3- dimensional box, letting you see the spatial area occupied by the group or filament. If you have “Show filament/group labels” checked, all highlighted objects will be labelled. The Deselect all button quickly turns off all highlighted objects. You will probably find that the most useful object category is “filament family”. Highlighting a family automatically highlights all the connected filaments in that family. Over a dozen filament families can be highlighted in Deep Space Explorer. When examining the large-scale structure of the Tully Collection, it is best
  35. 35. The Tully Collection 35 to begin about 800 MLY from Earth, with this region and it can be identified by a view similar to highlighting the `Great Attractor' family. “Viewing the Tully Collection” on page 31, so that you can see the position of There are great arcs of galaxies appended the family you are examining in relation to to the Great Attractor region. The most the entire database. You can then zoom in impressive is highlighted as the to examine the structure of the filament in `Pavo-Indus Arc', which arises out of the more detail. Centaurus Cluster region and the Norma Cluster, the latter buried in the zone that is Tip: You may wish to play with some of the obscured by the Milky Way. The options in the Settings pane (described in `Hydra-Cancer Arc' arises out of the “Galaxy Drawing Options” on page 37) to Hydra I Cluster. The `Milky Way Arc' produce the clearest view of the Tully emanates from the Centaurus and Norma Collection. This will make it easier to clusters vicinity and arches half way examine the structure of filament families. across the sky in close proximity to the plane of the Milky Way. Three gigantic structures dominate the cube that encloses the Tully Collection, The combination of the Great Attractor, and you can view any of these structures Pavo-Indus Arc, Hydra-Coma Arc, and by highlighting the appropriate filament Milky Way Arc families constitute the families. Local Supercluster Complex. We belong to the structure known as the The second gigantic structure in the Tully Local Supercluster complex. The part of Collection is known as the ‘Great Wall’ the complex closest to home, centred on family, and it is even more spectacular the Virgo Cluster, has been known for than our Local Supercluster Complex. The many decades and is called the Local Coma Cluster lies near the center of the Supercluster. Two orthogonal structures wall as we see it and the Hercules Cluster can be seen by highlighting alternatively lies near the edge. The Great Wall extends the ‘Supergalactic Equatorial Plane' family beyond the boundaries of the Tully and the `Local Supercluster Layered Wall' Collection, so we can only view part of it family. The `Virgo Flower Petal' family in Deep Space Explorer. shows how filaments connect into the nodal Virgo Cluster in 3-dimensions. The third major structure is seen by highlighting the combination of the About two decades ago astronomers began `Perseus-Pisces Arteries' and the to realize that the Local Supercluster is `Southern Wall'. The Perseus-Pisces just an appendage on a much larger Arteries are prominent twisted string-like structure centered on the Centaurus features. The Southern Wall is a huge Cluster. Everything in our local sheet-like arc. supercluster is moving towards this structure at a speed of 600 km/s. The name `Great Attractor' was coined to identify
  36. 36. 36 Deep Space Explorer User’s Guide You should use the structures mentioned This should help you visualize the 3-D above as a starting point for your structure of these two families. You explorations, not a complete guide. Many will notice that these structures are at of the regions in the Tully Collection have right angles to one other. not been studied in depth and there are plenty of structures remaining to be 8 Check the box for “Great Attractor” to discovered! turn on this major family. Example 2: Examining the Local Super- 9 Much of the Great Attractor will not be cluster Complex visible in your current view, so use the 1 Press the Home button to reset your Increase Elevation button until you are view. again 800 MLY from the sun. Check and uncheck the “Great Attractor” box 2 Use the Increase Elevation button to to see that it is a much larger filament increase your elevation until you are than the “Supergalactic Eq Plane” and about 800 MLY from the sun. You the “Local SC Layered Wall”. should now be able to see the entire Tully Collection. 10 Check the boxes for the “Pavo-Indus Arc”, the “Hydra-Cancer Arc”, and the 3 Press the Highlight pane in the “Milky Way Arc”. You have now Navigation bar. Make sure that “Show turned on all the filaments that bounding boxes” and “Show filament/ comprise the Local Supercluster group labels” are unchecked. Complex. Use the Location Scroller to rotate your view of this massive 4 Check the boxes for “Supergalactic Eq structure. Plane” and “Local SC Layered Wall”. These are the two structures of the local supercluster complex that are closest to home. 5 Use the Location Scroller to rotate your view of the Tully Collection. Note that all galaxies in these filaments are near the center of the dataset. 6 Use the Decrease Elevation buttons until you are about 300 MLY from the sun. 7 Practice alternately checking and unchecking the boxes for “Supergalactic EqPlane” and “Local SC Layered Wall”. Use the Location Scroller to frequently rotate your view.
  37. 37. Chapter 5 Altering the Look This chapter describes how you can customize Deep Space Explorer to look exactly how you want. Most of the tools discussed in this chapter are in the Settings pane and the Labels pane in the Navigation bar. Galaxy Drawing Options The 28 000 galaxy database was discussed in “The Tully Collection” on page 29. You have great control over how this database is displayed onscreen, in the Settings pane. Number of galaxies: This slider controls the number of galaxies drawn onscreen. The criteria for determining which galaxies to draw is their distance from your current position and their inherent brightness. When the slider is near the left edge, only the brighter galaxies are displayed. This is useful if you are simulating a flight through the universe, because the distant background galaxies are eliminated and it is easier to see the apparent motion of the nearby galaxies. Moving the slider all the way to the
  38. 38. 38 Deep Space Explorer User’s Guide right edge displays all 28 000 galaxies in Scale of close galaxies: When a galaxy is the database. This is useful if you are very close, it is represented by a full- examining filament families or other large- colour image instead of a dot. This slider scale structure in the database. lets you enlarge these galaxy images. The “correct” position of the slider is all the Use magnitude cutoffs: If you check this way to the left-this will draw galaxies the box, only those galaxies whose absolute proper size, and you will rarely see more magnitude lies within a certain range are than one or two galaxy images onscreen at displayed. Remember that absolute the same time. Moving the slider to the magnitude is a measure of a galaxy’s right allows you to see many galaxy inherent brightness, and therefore its size images at the same time, producing some and mass. Lower magnitudes correspond spectacular views. to brighter (and bigger) galaxies. You can set both an upper and a lower limiting Colour Saturation: Each different type of magnitude. For example, to quickly find galaxy is represented in Deep Space just the largest galaxies in the database, Explorer with its own colour image. The you could set the magnitude range from dots used to represent a distant galaxy are -21.0 to -30.0. This would display only the same colour as the full-size image. those galaxies brighter than magnitude Moving this slider to the right makes the -21.0 (the brightness of approximately 20 colour of the dots closer to that of the billion suns!). The Millky Way has a galaxy image, while moving the slider to magnitude of -21.12, so it would be the left strips away all colour distinctions shown, but the Large Magellanic Cloud until all galaxies are represented by white has a magnitude of -18.82, so it would not. dots. The advantage of having the slider far to the right is that you can quickly Example 1: Finding Dwarf Galaxies identify the galaxy type, for example, a 1 Press the Home button cluster of blue dots indicates a group of elliptical galaxies. The disadvantage is that 2 Click the Settings pane. the sky becomes gaudy and unrealistic- looking. 3 Check “Use magnitude cutoffs” and set Brightness: When a galaxy is too far away the “Brightest” value to around -15, and the “Dimmest” value to -10. Most for its image to be visible, Deep Space of the galaxies will disappear from your Explorer will represent its position in screen. space with a dot. This slider controls the brightness of these dots. The ideal position 4 Click the Labels pane and check the of this slider will depend on the brightness “Galaxy Labels” checkbox. All of the of your monitor and the lighting galaxies that are visible will be dwarf conditions in your computer room. galaxies, including the Sculptor Dwarf Moving this slider to the right makes the and the Pisces Dwarf. dots larger and brighter, while moving it to the left makes the dots smaller and dimmer.
  39. 39. Altering the Look 39 Example 2: Creating a “Hubble Deep Field” “Onscreen Info (Extrasolar Planets)” on view page 27 to learn how to get information on 1 Choose Edit->Find and type in “M87”, these extrasolar planets. then hit the Find button. M87 is a giant elliptical galaxy that lies at the heart of Labels the Virgo cluster, which is a dense collection of 2000 galaxies located 60 The Labels pane million light years from Earth. lets you customize the appearance of 2 Use the Decrease Elevation or Increase labels for stars, Elevation buttons to change your planets and elevation to about 6 MLY above M87. galaxies. You can control the number 3 Move the “Close galaxies” slider all the of objects to label, way to the right. You should see images and the label font, of many nearby galaxies pop into view. style, size and 4 Use the Location Scroller tool to rotate colour. your view around M87. Images of many galaxies will move in and out of view. You should be able to see several dozen images onscreen at the same time. 5 Check out this website for links to Turning labels on/off: Check the box Hubble Deep Field photos and note the marked “Galaxy Labels” to turn on labels similarities with the scene you just for galaxies, or uncheck the box to turn created using Deep Space Explorer: them off. Ditto for stars and planets. Font: Choose from any of the fonts in the hdf.html pull-down list. Show Extrasolar planets: This is the only Style: Choose from regular, bold, italic, or control in the Settings pane which does not bold italic. involve galaxies. Instead it involves stars in our own Milky Way known to have Size: Set the size of your labels. planetary systems. At the time of writing, Colour:Click on the coloured rectangle to over 60 extrasolar planets had been open a window that allows you to choose a discovered, and these are all included in new label colour. Deep Space Explorer. When you are positioned inside the Milky Way and you Number of Labels: Move the slider to the have “Show Extrasolar Planets” checked, right to draw labels for more objects, or to stars with planetary systems are marked the left to draw fewer labels. This is only with a special icon. See an option for stars and galaxies. For
  40. 40. 40 Deep Space Explorer User’s Guide planets, either all or none of the planets are labelled. Scale With Distance: An option for galaxies only, this connects label size with object distance. The closer a galaxy is to you, the larger its label will appear. This makes it easy to identify the nearest galaxies.