01Lab_Intro-to-Stellarium_2023_red

M ONTGOMERY C OLLEGE – R OCKVILLE A STRONOMY 101 ASTR101 Laboratory 1 - Introduction to Stellarium 1 Name: Aditya Rana The purpose of this exercise is to gain familiarity with the Stellarium 2 program and its many capabilities and features. Stellarium is a visually beautiful and powerful program that accurately displays the sky as seen from any place on Earth (or from any other planet!) at any time. It's easy to use, but also full of accurate astronomical information. If you have patience and follow the guidance in this and future assignments, by the end of the semester you will be experts at using this amazing program. You will want to keep and use Stellarium for years to come, as your personal planetarium and observatory. And the best thing about the program? It's free! If you’re not doing the laboratory on campus, or if you simply want to have Stellarium at home, you can download the program at www.stellarium.org . PART A Now let’s start the program. Double-click on the Stellarium icon (it shows a small crescent Moon and some stars above a horizon) that should now be on your computer’s desktop or in one of its menus. You are looking at the sky and the Southern horizon, as they appear right now, in a field outside Paris, France (the author of the program is French). Your location information is always listed in the Information Bar at the bottom of the screen. Our first task is to set our home location – this is the viewing location that the program will automatically use to display the sky every time it starts. For us, obviously, this will be Rockville . When you move your cursor to the lower left-hand corner of the screen, two menu bars appear - a horizontal one on the bottom of the screen and a vertical one on the left side of the screen. Each of these menu bars display some icons. When you click on any of these icons, a corresponding window opens up to control a particular part of the program. On the left-hand side vertical menu bar, click on the Location Window icon (it looks like a compass symbol). This will open the Location window. You can also simply press F6 to open the Location window if you have a Windows PC. 1 Last edit Spring 2022 (MC). 2 This lab is based on version 0.21.3 of Stellarium . If you are using and older or newer version, the GUIs may be slightly different. Please ask if you have questions. 1

ASTR101 L ABORATORY 1 In the Location window you will see a map of the Earth on the left and a list of locations on the right, below which is a search box (where the magnifying glass icon is) to enter a location. Type Rockville into the search box. Click on Rockville, United States when it appears in the list above. Once you've clicked on Rockville, your location is instantly switched to Rockville! Alternatively, you can enter the Latitude and Longitude of Rockville directly into the program, with the controls below the map. The Latitude of Rockville is 39° North , and the Longitude is 77° West . If you’re using your own computer, you can save this as the default location so that every time you start the program you will be observing the sky from Rockville. To do this, click on the Use current location as default box in the lower left-hand corner of the Location window to put a check mark in it, and then close the Location window by clicking on the X in the upper right-hand corner of the Location window. Stellarium can accurately show you exactly which stars, planets, nebulae, galaxies, asteroids and comets are in the sky at any time, give you information about them, and show you how they all change positions as time passes. It's a very exciting program, but it takes a bit of getting used to. If you ever need help within the program, click on the Question Mark button in the lower left edge (or press the F1 key), to open the Help window. You’re now ready to start exploring Stellarium ! First let’s look around the screen. You are looking at a view of the sky, with the ground below it. You are facing South (see the red “ S ” on the ground at the center? – that means “South”), and you should be located in Rockville, indicated by “ Earth , Rockville ” in the Information Ba r at the bottom of the screen. The time and date listed to the right in the Information Bar should match the local time (as long as your computer itself has the correct time!). If you’re doing this assignment during the day, the sky looks blue, as you would expect. If you’re doing it at night, the sky looks dark, and there are stars (and perhaps planets and the Moon) visible, again, as you would expect. Let’s start navigating around the program. The buttons on the two menu bars have icons that represent various functions of the program, and each opens a window that allows you to change various parameters of the program. The most important button is the Sky and viewing options window button, which has star and planet symbols on it. This button opens the View window, which has five sub-menus. Press the Sky and viewing options button to open the View menu. You can also open this menu by simply pressing the F4 key on a Windows PC. List five of the sub-menus accessible from the View Window. (There are more than five.) 2

ASTR101 L ABORATORY 1 the “Show Labels” box under “Options”? Now go to the SSO submenu. If they're not already checked, click on the boxes next to Solar System objects and Labels and Markers . Close the View menu. Now open the Date and Time window by clicking on its icon (a little clock) in the left-hand menu bar. By clicking on the arrows above or below each number in the Date and Time window, change the date and time to January 1, 2014 , at 4 PM in the afternoon. ( Stellarium uses “military time,” where 1PM = 13:00, 2PM = 14:00, etc.). What happens to the sky and the objects in the sky as the date and time change? The sun appears to set. Move forward in time by clicking on the upward arrow above the minutes in the Date and Time window. What happens to the sky as you move forward in time? Describe the movements. The sun sets to the west and sky darkens. Keep going forward with the minute button. What direction do the stars appear to move? The stars appear to move clockwise towards the west. Close the Date and Time window by clicking on the “x” in its upper right-hand corner. Press the Page Down button a few times (or CTRL and the Down Arrow key) on your computer as you watch the screen. What happens when you press Page Down (or CTRL and Down Arrow )?? The Camera FOV changes, it zooms out . What happens when you press Page Up (or CTRL and Up Arrow )? The Camera FOV changes, it zooms in. 4

ASTR101 L ABORATORY 1 Use the Date and Time window to go back to 4 PM. The Sun should be visible. Now press the A button your keyboard. This button is called the Atmosphere button. What happens when you press the A key? The sky disappears and the stars become visible. Are there any objects near the Sun? If so what do you see? Mercury, Moon , Venus Now let's start changing some settings in the program. One of the nice features of Stellarium is a series of simple keyboard commands that perform shortcuts. For example, to instantly change Stellarium to display the sky at the current time , just press the 8 key. Try it! Now change the time and date back to 12 Noon on today's date, using the Date and Time window. Use the “ A ” key to turn off the atmosphere on and off a few times. Leave the atmosphere on so that the sky is blue when the Sun is out. Now move forward in time until after sunset and the sky is dark. Now press the “ F” button on your keyboard. This is the Fog button. You may have to press it several times to notice what happens. Look carefully near the horizon. What happens? Fog disappears and the horizon becomes clearer. Now press the “ G” button on your keyboard a few times. This is the Ground button. What happens? The horizon disappears and the entire night sky becomes visible. Press the “G,” button again to turn the Ground back on. If you ever want to see what stars are out during the day, you can do it with Stellarium by simply pressing the “ A” key! Note that you can also turn the Ground , and Atmosphere on and off using their icons in the toolbar at the bottom of the screen. Suppose you wanted to look at a different part of the sky than the Southern horizon? No problem! There are many ways to “point” in a different direction. Perhaps the easiest one is to “grab” the sky and drag it. To do this, just click and hold the left mouse button down while dragging the mouse. As you do so, the sky is dragged. Try it. Let go of the sky and drag it again until you are looking at the Northern horizon. Now look at the Eastern & Western horizons. 5

ASTR101 L ABORATORY 1 To see this, center the Eastern horizon on the screen (by dragging the sky until the “ E ” is in the center of the screen), zoom in until the Field of View is about 30° (you may have to drag and recenter the “ E ” as you zoom to keep it from drifting off screen). Open the View window and Set the Landscape to “Garching”. Also make sure there are checks in the boxes next to Stars and Solar System Objects in the Sky and SSO sub-menus. Next set the Date and Time to September 22, 2021 at 12:25 AM . Remember, Stellarium uses military time, so 12:25 AM is 0:25. Close the window and simply watch the sky. Let the program run for at least 5 minutes. What object rises just slightly north of east at 12:26 AM? Bellatrix the amazon star Suppose you don't want to wait for things to happen in “real time.” Suppose you want to make the time pass faster. No problem. Reset the time to 12:20 AM , and this time look at the buttons at the right side of the bottom tool bar . These are the time control buttons. One looks like a triangle – like the “play” button in a DVD player. This is the Set normal time rate button. To the right of this is one that looks like an hourglass. This is the Set time to now button that automatically sets the time to the current time. Press it. Did the time and date change? To the right of this button is the “Fast Forward” button – it's two triangles. This is the Increase time speed button. Finally, the farthest button to the left is the Decrease time speed button. Each of these buttons has a keyboard shortcut – pressing the K key is the same as pressing the Set normal time rate button, pressing the 8 key is the same as pressing the Set Time to Now button, pressing the L key is the same as pressing the Increase time speed button, and pressing the J key is the same as pressing the Decrease time speed button. Reset the time and Date back to January 20, 2014 , at 10:04 PM . Press the Increase time speed button once (or simply press the “L” key on your keyboard). Watch the sky and look at the time in the Information Bar What do you notice about the way time is passing? Time is moving faster Press the Normal Time Rate button (or the K key) and reset the Date & Time again to the current time and date by pressing the 8 key. 7

ASTR101 L ABORATORY 1 What happens if you press the Increase time speed button two times? Minutes pass by as seconds. What happens if you press the Increase time speed button four times? Hours pass by as seconds. Press the Set normal time rate button (or press the K key) to return to normal time. Now press the Decrease time speed button (or press the J key). How is time passing now? Time Paused What happens if you press the Decrease time speed button two times? Time starts going backwards What happens if you press the Decrease time speed button three times? Time goes back in minutes. Each time you press the Increase time speed or Decrease time speed button, the time speed is changed by a factor of 10 times slower or faster. We can also step time forward in discrete units. For example, we can make time go forward by one hour or one day in one single jump. Let's do this. Press the Set time to now button (or press the 8 key) and the Set normal time rate button (or the K key) to make time go normally. Look at the Information Bar to see what day and time it is. Now press the CTRL and “=” (equals) keys on your keyboard and look at the Date & Time in the Information Bar again. What happened to the date and time when you press “ CTRL and = ”? Time goes forward by an hour. Now press CTRL and “-” (minus) keys on your keyboard and then look at the Date & Time . What happened to the date and time when you press “ CTRL and - ”? Time goes backward by an hour. Now press the “-” key on your keyboard, and then the “=“ key as you look at the Date & Time . 8

ASTR101 L ABORATORY 1 find when Mars sets, i.e. when it first goes below the western horizon. You will need to move the horizon so you’re facing southwest. What time does Mars rise on January 1, 2022? 5:34 am What time does Mars set on January 1, 2022? 2:45 pm Stellarium also has a useful function that allows you to find any object in the sky. To use it, click on the Search Window icon (the little magnifying glass) in the left-hand menu bar (or simply type CTRL-F or press the F3 key) to open the Search Window . Once the Search Window is open, simply type in the name of the object you're looking for in the box, and hit Enter . Stellarium will select that object, center it on the screen, and display its information in the upper left-hand corner. If the object is not in the sky at the moment, Stellarium will point at the ground, since that's where you would have to look to see it! To see the object in this case, you have to make the ground disappear. Do this by pressing the “ G ” key on your keyboard. Find the planet Jupiter . Center the planet with the space bar, then zoom in to it until you can see the planet as a disk. An easy way to do this is by simply pressing the “/” (“slash”) key. Do you see the four labeled dots to one side or another of Jupiter (their names are Io , Europa , Ganymede and Callisto )? What do you think these objects are? Jupiter’s Moons Let's look at one of the so-called “ Deep Sky ” objects. We'll find out later in the semester what this term means, but for now, let's just say they're exciting, far-away objects in the sky. Use the Search Window to find M31 . M31 is also known as the Andromeda Galaxy! Zoom in or out until the Andromeda Galaxy fills the screen! Describe the Andromeda Galaxy. From the disc image of the galaxy it looks bright in the middle with blue and brown lines around it. The “M” in M31 stands for Charles Messier, a famous astronomer from the 18th century. Try picking another “M” object by typing in another number (1-103) after M in the Search window. Zoom in to see your new Messier object up close. 10

ASTR101 L ABORATORY 1 Which object did you choose? M14 Describe your object. It is a star cluster with much Stars ground together in the deep space. Finally, close Stellarium by clicking on the Quit button at the right of the toolbar at the bottom of the screen. Whew! As you can see, Stellarium is a beautiful, powerful and complex program. We will make good use of it this semester, however it will take some getting used to! Don’t worry! Soon you will have mastered it. 11