4-H MOTTO 4-H PLEDGE 4-H GRACE. Learn to do by doing.

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2 4-H MOTTO Learn to do by doing. 4-H PLEDGE I pledge My HEAD to clearer thinking, My HEART to greater loyalty, My HANDS to larger service, My HEALTH to better living, For my club, my community and my country. 4-H GRACE (Tune of Auld Lang Syne) We thank thee, Lord, for blessings great On this, our own fair land. Teach us to serve thee joyfully, With head, heart, health and hand. This project was developed through funds provided by the Canadian Agricultural Adaptation Program (CAAP). No portion of this manual may be reproduced without written permission from the Saskatchewan 4-H Council, phone , info@4-h.sk.ca. Developed: December Writer: Paul Lehmkuhl

3 Table of Contents Introduction Overview... 1 Achievement Requirements for this Project... 1 Chapter 1 What is Astronomy? Astronomy is a Science... 2 Astronomy vs. Astrology... 2 Why Learn about Astronomy?... 3 Understanding the Importance of Light... 3 Where we are in the Universe... 5 Looking Back into Time... 6 Safety and Precautions in Astronomy... 6 Chapter 2 Using Your Telescope Types of Telescopes... 8 How Telescopes Work Tips for Purchasing a Telescope Mounting and Tracking Understanding the Magnitude Scale for Brightness General Guidelines for Using your Telescope Weather and Light Pollution Binocular Astronomy Chapter 3 Tools and Online Links Astronomy Apps Taking Pictures of Astronomical Objects Online Links Chapter 4 The Constellations What are the Constellations? Navigating Around the Sky How to Find Some Common Constellations Chapter 5 The Moon What is the Moon? Phases of the Moon Harvest Moon... 43

4 Tips for Observing the Moon Eclipses Chapter 6 The Solar System Getting to Know the Sun and the Planets Finding Planets with your Telescope Asteroids, Comets, Meteors and Meteorites Aurora Borealis Chapter 7 What are Stars? How Stars are Born, Live and Die Different Types of Stars Finding Stars to Observe with your Telescope Chapter 8 What Else is Out There? Galaxies Star Clusters Nebulae Finding Galaxies, Star Clusters and Nebulae with your Telescope Chapter 9 Astronomy and Agriculture Constellations and Agriculture Seasons and the Sun Observatories in your Area Dark Sky Areas Royal Astronomical Society of Canada Chapter 10 Careers in Astronomy How to Become an Astronomer What do Astronomers do? Glossary of Definitions... 86

5 Introduction Overview Have you ever looked up at the night sky and wondered what's out there? Have you ever asked yourself "What are the stars and planets made of? Where do stars come from? What are the constellations and how do I find them? Why does the Moon go through phases? Are there planets out there beyond the Earth that contain life? These are only a few of the questions that astronomy digs into. If you find these questions interesting then this 4-H Project is for you! This reference book will guide you through the science of astronomy and by the end you will be able to navigate around the sky; you'll know how to use a telescope; and you'll have a strong understanding of the characteristics of various objects that are out there in our universe. Achievement Requirements for this Project A completed record book Complete at least two discussion activities Complete at least two research activities Complete at least two concept activities Complete at least two build activities Complete at least two navigation observation sheets Complete at least two solar system observation sheets Complete at least two star observation sheets Complete at least two deep sky object observation sheets Astronomy Reference Book 1

6 Chapter 1 What is Astronomy? Astronomy is a Science For thousands of years people have looked up at the night sky and wondered what is out there. Ancient civilizations from all over the world recognized that the universe is structured, ordered and that there are regular patterns that occur. We can attribute our current understanding of the universe to the ancient Greeks who laid the foundation for the science of astronomy. Greek philosophers realized that we could understand the patterns in the universe by using logic, reason and mathematics. A simple example of a regular pattern in the world is the seasons. The seasons change throughout the year from winter to spring to summer to fall and back to winter. We will see in a later chapter that the seasons change due to the tilt of the Earth as it orbits around the Sun. If we recognize a pattern in the universe, then we can try to figure out why it happens. This process of figuring out why something happens in the world is called the scientific method. The science of astronomy makes use of the scientific method to explain how the universe works. Astronomy vs. Astrology Without having a background in astronomy it is easy to confuse astronomy with astrology. Astronomy is a rigorous science that follows the scientific method. Some questions that an astronomer might ask are: Where did the Earth, planets and stars come from? What is happening on the other planets? What is going on inside the Sun? What happens when a star dies? What is light? What is space and time? Why does the moon go through phases? Why do the seasons occur? What is the difference between a meteor, a meteorite, an asteroid and a comet? Is there life on other planets beyond the Earth? How big is the universe and is there an edge? How old is the universe? 2 Astronomy Reference Book

7 In other words, astronomy studies the universe on a large scale. Astronomers are interested in what is going on out there in the universe and they apply the scientific method to find these things out. Astrology, on the other hand is not grounded in the scientific method. Astrology also assumes that there is a connection between astronomical events and the human world. For example, an astrologer might claim that a particular configuration of the planets would allow her to predict the future. This makes the assumption that there is some connection between planetary configurations and human beings. In the science of astronomy, there is no evidence to support that there is any connection between the planets and what goes on in the lives of human beings. Why Learn about Astronomy? Astronomy can make you feel connected to the universe in a deep way. By studying the night sky we begin to understand where we came from and our place within the universe. We often get caught up in everyday life and we neglect the big picture. When you study astronomy it takes you on a trip beyond the Earth, beyond the solar system and even beyond our galaxy. Understanding the Importance of Light Light is one of the most important aspects of astronomy. Everything that we can see in the night sky, whether it is a star, a planet or a galaxy, emits light. If an object did not emit light then we would not know it was there. Objects such as stars, galaxies and nebulae generate their own light whereas planets and the moon reflect sunlight and do not create their own light. Human eyes are capable of seeing only a tiny fraction of the entire light spectrum. Light is not just what we can see; the light spectrum also includes microwaves, radio waves, infrared light, x- rays and gamma rays. The difference between visible light and x-rays for example is that x-rays are oscillating at a much higher frequency and they have a smaller wavelength than visible light. Radio waves on the other hand have a much longer wavelength and smaller frequency than visible light. The human eye can only see in visible wavelengths but we have developed the technology that has allowed us to see and use light from other parts of the spectrum. For example, we use radio waves for FM and AM radio. We use x-rays for checking for cavities when we visit the dentist, and we use microwaves for heating up food. Using certain technology, astronomers are able to see in other wavelengths besides the visible part of the spectrum. The following diagram shows the light spectrum and the relative sizes of the different wavelengths of light: Astronomy Reference Book 3

8 Light spectrum with relative sizes of wavelengths, Wikipedia, Inductiveload, NASA, 2007 What is Light-Speed? Light travels at the staggering speed of 300,000 kilometres per second. To put this into perspective, light could travel seven and a half times around the Earth in just one second. When you turn on a lamp the light seems to hit your eye instantly. In reality, the light is travelling extremely fast to hit your eyeball so it only appears to turn on in no time at all. The distance between your eye and a light bulb is very small so the light hits your eye within a tiny fraction of a second. What is a Light Year? The universe is so big that Astronomers talk about light years when describing the distance to stars, galaxies and other far away objects. A light year is the distance that light can travel in one year. If we want to find out the distance of a light year in kilometres we would need to multiply the speed of light by the number of seconds in one year. Think about it this way, if you are driving in a car at 100km/hr and you want to know how far you have gone in two hours, you would just multiply your speed by the length of time that you were driving at that speed. 100km/hr multiplied by two hours gives 200km, so in two hours you would have travelled 200km. So what is the distance that light travels in one year? As we saw before, light travels at 300,000 kilometres per second. What we need to find out is how many seconds there are in a year and then multiply that by the speed of light. There are 365 days in a year, each day has 24 hours, each hour has 60 minutes and each minute has 60 seconds. So that means there are 365 x 24 x 4 Astronomy Reference Book

9 60 x 60 = 31,536,000 seconds in a year. Now multiply the speed of light by the number of seconds in a year and we get: 300,000 kilometers per hour x 31,536,000 seconds = 9,460,800,000,000 kilometres. That means that one light-year is equal to just under 10 trillion kilometres. The sun is eight light minutes away from the Earth, meaning that it takes 8 eight minutes for light to travel from the Sun to the Earth. If the sun were to suddenly explode, we would not know about it for eight minutes because it would take the light from the explosion that long to get here! Where we are in the Universe The universe is big... really big. To get us started in understanding where we are in the universe first consider this question: What is the closest star to us? If you answered the sun then you are correct. Sometimes people forget that the sun is in fact a star. Moving out from the sun there are the eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. The next closest star to the Earth is one called Proxima Centauri, located 4.2 light years away, meaning that if you could travel at light speed then it would still take 4.2 years to get there from the Earth. To find out the distance between the Earth and Proxima Centauri in kilometres we would take the distance of 1 light-year (10 trillion kilometres) and multiply this by 4.2, giving us roughly 40 trillion kilometres! The Milky Way galaxy contains billions of stars beyond the sun. If you are in an area that is very dark, away from city lights, you can easily see the Milky Way with your naked eye. It looks like a thick band of stars running from one end of the horizon to the other. Astronomy Reference Book 5

10 Milky Way over Saskatchewan courtesy of Jeff Swick Beyond the Milky Way galaxy there are, you guessed it, billions of other galaxies spanning the whole universe. Each galaxy contains billions of stars all gravitationally attracted to one another. The nearest galaxy to us is one called the Andromeda Galaxy. Even though it is the closest to us, it is still 2.5 million light years away. That means that if you could travel at the speed of light, it would take you 2.5 million years to get there from the Earth! Surprisingly, the Andromeda Galaxy is an object that you can actually see with your naked eye on a dark, moonless night. In a later chapter we will see how you can navigate around the sky to find it. Looking Back into Time Astronomy might be the only science where you actually get to experience time travel. As we saw before, light travels at the staggering speed of 300,000 kilometres per second. In everyday life we do not notice the time that it takes light to get to our eyes because in everyday life we deal with relatively small distances. In Astronomy the effects of light speed become more obvious because anything we look at is so far away. For example, we know that the sun is eight light minutes away from the Earth, which means that you are seeing the sun as it was eight minutes ago, since it has taken light that long to reach your eye. You will never see the sun right now because the light from the sun has taken eight minutes to travel through space from the sun to your eye. Let us take this idea further. If you look at Proxima Centauri, the next closest star to the Earth, it is 4.2 light years away. When you look at Proxima Centauri you are seeing it as it was 4.2 years ago because it has taken light that long to reach your eye. Let us go even further. The Andromeda Galaxy as we saw is 2.5 million light years away, which is the nearest galaxy to our own. If you look at the Andromeda Galaxy you are seeing it as it was 2.5 million years ago because it has taken light that long to reach your eye as it travelled through space! Safety and Precautions in Astronomy Here are some tips on how to stay safe and be prepared when completing this project: Think about your goals. Plan your night of observing. Ensure that an adult is with you when you venture out to observe the sky. Be prepared Make a checklist of the things that you will need to take with you when you are observing. Examples are flashlight (with a red light bulb), pencil, eraser, binoculars, telescope accessories. Try to find a dark, safe place away from light pollution for observing. Watch your step in the dark. 6 Astronomy Reference Book

11 Bring a flashlight with you to make sure you can see where you are going in the dark (most astronomers use a flashlight with a red light bulb because your eyes will more easily adjust to the darkness). Never look directly at the sun and never point a telescope or binoculars at the sun! Dress warm! Even if it seems warm out, the temperature can drop quickly at night time so be aware that you should always dress warmer than you think is necessary. Especially if you live in an area where the temperature drops far below zero, make sure that you bundle up. Be safe online! If you are ever doing online research, or visiting chat rooms and blogs, never share any personal information. Be sure to tell your parent or guardian if you ever feel unsafe or uncomfortable online. Astronomy Reference Book 7

12 Chapter 2 Using Your Telescope Types of Telescopes There are two types of telescopes, refracting telescopes and reflecting telescopes. Refracting telescopes use glass lenses whereas, reflecting telescopes use mirrors rather than lenses. Refracting Telescopes A refracting telescope contains two lenses, an objective lens and an eyepiece lens. The objective lens is found near the end of the telescope tube and is responsible for gathering and focusing the incoming light from a star, planet or other object. The lens in the eyepiece then takes all that collected light and magnifies the image before it enters your eye. Refracting telescope cross section, WikiCommons, MesserWoland, 2006 Celestron Refracting Telescope, WikiCommons, fractal.scatter, Astronomy Reference Book

13 Reflecting Telescopes In a refracting telescope the light passes through two lenses before it hits your eye. A reflecting telescope, on the other hand contains two mirrors that reflect the light within the tube. The light is directed to the lens in the eyepiece where the image is magnified before it enters your eye. There are two main types of reflecting telescopes, Newtonian and Cassegrain. A Newtonian Reflecting Telescope has a curved primary mirror at the base of the telescope tube and the light is reflected to a flat secondary mirror further up the tube. The flat mirror is on an angle, which redirects the light into the eyepiece. The eyepiece is conveniently mounted on the side of the telescope that you can look through to see a magnified image. Newtonian reflector cross sections (dotted line is incoming light), Wikipedia, Tamasflex, 2009 Newtonian telescopes, WikiCommons, Analogue Kid, 2006 Astronomy Reference Book 9

14 A Cassegrain reflecting telescope has a curved primary mirror at the base of the telescope and the light is reflected to a flat secondary mirror further up the tube. The light is then reflected back to the base of the tube through a slit in the primary mirror. The eyepiece is mounted at the base of the telescope that you can look through to see a magnified image. Cassegrain reflector cross section (red dotted line is incoming light), WikiCommons, Tamasflex Celestron Cassegrain reflector, WikiCommons, Staycoolandbegood, 2005 How Telescopes Work All telescopes have one thing in common; they make faraway objects look closer. To understand how a telescope does this, first think about your eye. The pupil is the part of your eye that lets a certain amount of light in. The lens it located behind the pupil and is responsible for focusing the light onto the retina. WikiCommons, BruceBlaus, Astronomy Reference Book

15 Light entering eye with lens focusing light onto retina, WikiCommons, Ruth Lawson, 2007 Your eye and a telescope are actually quite similar; they both let a certain amount of light in and they also focus the light. Think about a refracting telescope. The primary lens of a refracting telescope lets a certain amount of light go through and it also focuses the light. A telescope lens is much bigger than your pupil so a telescope can gather much more light compared to your eye. When you look through a telescope, all that light that is collected is directed into your eye. Essentially, a telescope makes your eye as big as the lens so you can see things that are very far away. The strength of a telescope depends on how much light it can collect. A telescope with a bigger objective lens or primary mirror will have more light gathering power than a telescope with a smaller lens or mirror. This is very important to think about when you are considering purchasing a telescope. Tips for Purchasing a Telescope If you are considering buying a telescope there are a few things to keep in mind before making a purchase. Magnification is not the Most Important Part Some department stores and camera shops may advertise that their telescopes have very high magnification power. Keep in mind that magnification is the least important part of getting a bright, well-resolved image out of your telescope. If you want to make the image bigger or smaller, all you need to do is change the eyepiece. Many telescope kits come with different eyepieces, or you can purchase them in addition to your telescope if you want to have the option of changing the magnification. Look for Light Gathering Power A primary aspect that you should look for in a telescope is light gathering power. In other words, better telescopes have a greater ability to collect light. Telescopes that have bigger objective Astronomy Reference Book 11

16 lenses or primary mirrors have a greater ability to collect light; we call this the aperture of the telescope. If you find a telescope that you like, be sure to look closely at the telescope specifications on the package or ask an attendant for more details about the telescope. The aperture of a telescope will tell you how much light gathering power a telescope has. Refractor or Reflector? Both refracting telescopes and reflecting telescopes have advantages and disadvantages. It comes down to personal preference for what type of telescope you should get. Generally, larger refracting telescopes will be more expensive than reflecting telescopes with the same aperture. Unless you are doing some very detailed observing, you will not see a big difference when you look through a refracting or a reflecting telescope. The nice thing about reflecting telescopes is that they are pretty compact since the light is reflected within the tube before it hits the eyepiece. Refracting telescopes on the other hand are generally not as compact as reflectors because they have to be longer than the focal length of the objective lens. Used Telescopes It is a great idea to consider buying a used telescope rather than a new one because it can save you hundreds of dollars. Many used telescopes that you can find online are as good as new so you can often find a quality telescope at a much cheaper price than buying new. Some websites to check out for used telescopes and other astronomical equipment in Canada are: Be Realistic It s important to understand that when you look through a telescope, it is not going to look like some astronomy photographs that you see in calendars, online or on television. Pictures like that were taken with long-exposure imaging techniques using very high-powered cameras and telescopes. When you look through a telescope, the image will be black and white, and sometimes you will see some colour, depending on the object you are looking at. Take a look at the difference between the two following pictures of the Orion Nebula. The picture on the left was taken by an amateur astronomer who took the time process the image to give it colour. The image on the right is similar to what you would see as you look through a modestly powered telescope. 12 Astronomy Reference Book

17 Orion Nebula courtesy of Jeff Swick Processed image of the Orion Nebula courtesy of Tenho Tuomi Mounting and Tracking Telescopes can be pretty heavy and awkward so if you buy a telescope it is important to consider also buying a telescope mount. There are two basic types of telescope mounts, altazimuth and equatorial. Whenever you point your telescope to an object in the sky, you need to keep in mind that the Earth is rotating, and so within minutes, the object you are looking at may have moved out of the field of view. Some telescope mounts come with a tracking motor that allows the telescope to stay fixed on any object you point the telescope to. Tracking drives are more common on equatorial mounts than altazimuth mounts. Let us take a look at these two types of mounts in more detail. Altazimuth Mount Altazimuth is short for altitude-azimuth mount. The altitude is how high an object is above the horizon and the azimuth is where along the horizon you are looking. Altitude and Azimuth coordinates, WikiCommons, TWCarlson, 2012 An altazimuth mount allows the telescope to rotate in a circle around the base (along the azimuth) and up and down along the altitude. You can think of the base of Astronomy Reference Book 13

18 an altazimuth mount as a compass bearing in that you can point the telescope in any direction whether it s north, east, south or west. Then, you can pan the telescope up and down across the sky which allows you to see any part of the sky while facing a particular direction. The primary advantage to altazimuth mounts is their simplicity. The disadvantage is that tracking motors are usually not suited for altazimuth mounts. Newtonian reflector and Altazimuth mount, Wikipedia, ECeDEE, 2005 Equatorial Mount Before we talk about an equatorial mount, we should first look at astronomical coordinates called right ascension and declination. Right ascension (RA) and declination (Dec.) are coordinates that tell you where astronomical objects are found in the sky. Stand up and point your hand out directly in front of you, now start rotating your body slowly in a circle. As you do this you are moving in right ascension (similar to longitude). Now stop rotating, keep your arm pointed out in front of you and move it slowly up toward the ceiling. You are now moving your arm in declination (similar to latitude). Like coordinates on the Earth that tell you where certain cities or countries are located, RA and Dec. are used to tell you where objects like stars, galaxies and other deep sky objects are located. An equatorial mount allows the telescope to move in two directions, left and right around a circle (which corresponds to the right ascension) and up and down (which corresponds to declination). RA and Dec. coordinates, Wikipedia, Tfr000, Astronomy Reference Book

19 With an equatorial mount, the telescope is set up such that the right ascension wheel is parallel with the Earth s rotation axis. At the same time the telescope is free to move in a circle along the same direction that the Earth is rotating. Equatorial mounts are convenient because it is possible to use a clock drive to rotate the telescope at the same rate that the Earth is rotating and in the opposite direction. This cancels out the rotation of the Earth and so any object you point the telescope to will stay fixed on that object. Newtonian reflector with equatorial mount, Wikipedia, Tamasflex, 2009 Some telescopes have the coordinates of various astronomical objects programmed within them. These telescopes have a keypad with a "GoTo" function that allows you to select the object you want to look at and the telescope will automatically point to that object - you just have to make sure that your telescope is calibrated at the start of your observing night. Most telescopes come with instructions that show you how to calibrate your telescope. Cassegrain telescope with equatorial Mount and GoTo, WikiCommons, Kapege.de, 2009 Astronomy Reference Book 15

20 Understanding the Magnitude Scale for Brightness Astronomers have created a scale that tells you how bright a star is relative to other stars. The scale runs from negative numbers to positive numbers. It may seem backwards but a more negative number means that the object is brighter. For example, the sun is the brightest object in the sky and has a visual magnitude of The full moon has a visual magnitude of -13. The moon has a less negative number because it is not as bright as the sun. Vega, a relatively bright star in the constellation Lyra has a visual magnitude of 0. For dimmer objects, we start to move into the positive numbers. The visual magnitude of Mars is 1.8, a positive number, which means that Mars is dimmer than Vega. Assuming perfect weather conditions and no light pollution, the dimmest that an average person can see with their naked eye is magnitude 6. Uranus has a magnitude of 5.3, so the average person would just barely be able to make out this planet with their naked eye. Any object with a magnitude greater than 6 will require the use of binoculars or a telescope to see. Keep this in mind as you read through this reference book because then you will have an idea of what objects you will be able to see with your naked eye and what objects you will need to use binoculars or a telescope to see. 16 Astronomy Reference Book

21 General Guidelines for Using your Telescope Parts of a Telescope The parts of a telescope are shown in the diagram below. It may be helpful to familiarize yourself with these parts before you read on: Steps to Using your Telescope This section will outline some general steps in using your telescope when locating objects. This list is not comprehensive and there may be additional steps to consider depending on what you are observing and your specific telescope and mount. 1. Pick an object that you want to observe. Newtonian reflector telescope with equatorial mount, WikiCommons, Rogilbert, Ensure that the magnitude is reasonable (probably not dimmer than magnitude 10). 3. Ensure that the object is visible at that time of year (see Seasonal vs. Circumpolar constellations). 4. Calibrate Finderscope (or TELRAD) this means that the finderscope or TELRAD needs to be lined up parallel with the telescope tube so that when you look through the finder you will see the same part of the sky when you look through the eyepiece your telescope should come with instructions for how to perform this calibration (if not you can also look online). 5. Find a clear and dark place to go with your telescope. 6. Locate the constellation that the object is found in. 7. Find a star that is near the object that you wish to observe (if the object you wish to observe is a star then you can skip this step). 8. Line up your Finderscope or TELRAD with the star and ensure that you can see it in the eyepiece of your telescope Astronomy Reference Book 17

22 9. Make fine movements of your telescope to move it to the location of the object (some telescopes have fine adjustment knobs that you can use). 10. You should see the object within the eyepiece (if not, you can continue to make fine adjustments until you see it). Weather and Light Pollution There are two big factors that will make or break your night of observing: bad weather and light pollution. If the sky is too cloudy or hazy then it will really impact what you are capable of seeing during your night of observing. It is important to check the forecast before you head out with your telescope at night to be sure that the weather will cooperate. In the next section you will find links to some weather websites that are great for astronomers to use. The other factor that you will need to consider when observing the sky is light pollution. Light pollution makes it really hard for astronomers to see objects clearly when they look through their telescopes. Examples of light pollution are streetlights, car lights, house lights, stadium lights and even moonlight. All of these sources of light can make for poor viewing conditions. The best place to be when observing the sky is far away from any sources of light. You want to be in as dark a place as possible. People that live on farms or acreages are fortunate because there tends to be less light pollution in rural areas. In many areas away from the city you can see the vastness of the Milky Way Galaxy spanning from one end of the horizon to the other. If you live in the city, you might be surprised how many more stars you can see when you get far away from city lights. The image to the right shows you a comparison between a night sky without light pollution (above) and a night sky with light pollution from a city (below). Wikipedia, Jeremy Stanley, Astronomy Reference Book

23 Binocular Astronomy Before you invest in a new or used telescope you may want to try finding some celestial objects with a pair of binoculars. You might be surprised to find out how much you can see with just a pair of binoculars that you have lying around the house. Depending on the power of your binoculars and your viewing conditions, you should be able to see many objects brighter than magnitude eight. Astronomy Reference Book 19

24 Chapter 3 Tools and Online Links Astronomy Apps If you have a Smartphone, ipod, ipad, tablet or similar device there are some powerful apps that are very useful for navigating around the sky and locating objects. In fact, most of the apps will track your GPS coordinates and if you hold your phone up to any direction in the sky, it will show you what constellation you are looking at or what planets or other objects are up in the sky. Also, many of the apps out there will overlay the mythological image overtop of the pattern you will see in the sky. This is a great way to quickly and efficiently learn where the constellations are located and to learn their mythology. Here is a list of apps that are available for purchase or download for either Apple or Android products: Astronomy Apps Star Walk SkySafari SpaceMap Planets Astronomy Picture of the Day Google Sky Map Star Chart Star3Map Compatible with Apple products Apple or Android products Apple products Apple or Android products Apple or Android products Android products Android products Android products Taking Pictures of Astronomical Objects Digital Cameras If you are interested in taking pictures of astronomical objects then you may want to consider purchasing a digital camera that can mount to your telescope. Most telescope cameras are mounted where you would normally put the eyepiece. Digital telescope cameras will range in price from $150-$1,000 depending on the quality of the camera. It is possible to take a picture by holding a point and shoot camera up to the eyepiece of your telescope, however this is not 20 Astronomy Reference Book

25 recommended since it is difficult to get a quality image and you risk scratching the lens of the eyepiece or your camera. CCD Cameras Have you ever wondered how they get such amazing pictures of astronomical objects that you see in calendars, online or on television? These images are professionally processed and often high powered telescopes and cameras are used. Taking images like these yourself is not impossible, as long as you have the right equipment. A charge coupled device (CCD) camera is a special type of camera that mounts on your telescope where the eyepiece would normally be placed. A CCD camera is extremely sensitive to light and it is capable of taking long exposure pictures. CCD cameras are not cheap however; they usually will cost over $2,000 if you buy one new. Online Links There are many online resources that you can check out whether you are a beginner or seasoned astronomer. There are many websites, blogs and applets to check out that give great details on news, current events, constellation mythology, how to find certain objects in the sky, how to take pictures of astronomical objects, or you can just look at some incredible images that were taken with high-powered telescopes. There is even a website dedicated to creating an online network to search for extraterrestrial life. Below is a list of links with a description for what you can find at each one. Also included in this list are some websites for checking the weather before you go out observing. Astronomy Reference Book 21

26 Website What It s About Science news, articles and updates on astronomical events. You can also find updates to what planets will be visible throughout the year. Learn more about astronomy through games and online activities. Great website for news, current events, research and pictures. There is also a link that is updated regularly with tips for sky watching. The Royal Astronomical Society of Canada get involved with your local chapter to receive updates on current events in your area. This is a great place for beginner and amateur astronomers to connect within their community. There is an Ask an Astronomer link where you can contact an RASC member to get answers to your astronomy related questions. Amazing images taken with the Hubble Space Telescope; also find some great information and news related to astronomy. Find information, news, apps, interactive links and more. Information, news and research dedicated to the Search for Extraterrestrial Intelligence. Participate in the search for extraterrestrial life on your own computer by downloading a program that analyzes radio signal data. Updates on what s going on at the Canadian Space Agency. Canadian magazine dedicated to astronomy and stargazing. Linked to Google Earth, Google Sky is an interactive viewer that allows the user to navigate around the sky and locate objects. Weather websites Government of Canada weather website. A weather website dedicated to astronomers providing very detailed weather information. 22 Astronomy Reference Book

27 Chapter 4 The Constellations What are the Constellations? The constellations are patterns of stars in the sky connected by imaginary lines. People have used the constellations for thousands of years in navigating the Seas, knowing when to plant crops and even to tell time. For many civilizations they hold a mythological significance and the constellations tell a story. In these star patterns people have imagined animals, heroic figures, gods and even monsters. All the constellations are like a map in the sky. Astronomers use the constellations to navigate around the night sky in order to find stars and other interesting objects like galaxies and nebulae. For example, the constellation Ursa Major in Greek Mythology is the Great Bear and looks like this: Wikipedia, Till Credner, 2004 You can see that this pattern of stars in the sky makes out the shape of a bear. You might recognize this constellation as the Big Dipper, however, the Big Dipper is actually just a small portion of the larger constellation of Ursa Major. The Big Dipper portion makes up just the tail and the rear end of the Great Bear, as seen in the following picture. Constellations in the Northern Hemisphere The imaginary line that splits the Earth in half is called the equator. The equator cuts the Earth into two equal halves called hemispheres. Here in Canada we live in the northern part of the world and so we call this half of the Earth the northern hemisphere. In the northern hemisphere Astronomy Reference Book 23

28 we can see a collection of constellations that are different than the constellations they can see in the southern hemisphere. This is because in the northern hemisphere we are looking out into a different part of space than they are in the southern hemisphere. In this reference book we will focus on the constellations that are visible in the northern hemisphere. Seasonal Constellations vs. Circumpolar Constellations Consider this question: Why does the sun rise and set? The answer is that the Earth is rotating. The Earth completes one rotation in 24 hours so during that time one half of the Earth will be daytime and the other half will be night time. The Earth is rotating on an imaginary axis that runs through the North Pole and out the South Pole and is tilted by 23.5 degrees with respect to Earth s orbit. Earth tilted on its axis as it orbits the sun, Wikipedia, Tau olunga, 2006 As the Earth rotates on its axis, the sun appears to move across the sky from sunrise to sunset. In reality is it just the Earth that is rotating which makes the sun appear to move across the sky. The moon, planets and constellations will also rise and set as the Earth rotates. 24 Astronomy Reference Book

29 The long exposure image to the right shows star trails as a result of Earth's rotation. At the centre of the image is the North Star, the star in which the rotation axis of the Earth points toward. The Earth is rotating on its axis but it is also orbiting around the sun. The Earth takes days for one complete orbit around the sun. As the Earth orbits the sun, we can see different constellations throughout the year. Have you ever wondered why you can see the Orion constellation in the winter, but not in the summer? Or why you can see the Big Dipper year round when other constellations tend to disappear? The answer is that some constellations are seasonal (they are visible for part of the year and they set for the other part of the year) and other constellations are circumpolar (they are visible in the sky year round). Star trails with North Star at the centre, Wikipedia, Kevin Hadley, 2012 Let s look at an example of seasonal vs. circumpolar constellations. If you were to look at the constellation Orion from Saskatoon at 11 p.m. on December 2, 24 hours later Orion would appear in roughly the same place in the sky because the Earth would have gone through one complete rotation. If you were to look at the same spot in the sky on June 2, Orion would no longer be in that part of the sky since it would have set below the horizon. Orion, like all the constellations, is very slowly creeping across the sky as the Earth orbits the sun. For this reason, Orion is considered to be a seasonal constellation. Orion will set below the horizon in the summer months and it will rise to be visible in the winter months. The Big Dipper, on the other hand, is visible year round. You may notice that the Big Dipper changes its position in the sky, for example it might flip upside down in the wintertime, but you will never see the Big Dipper set below the horizon. For this reason, the Big Dipper is called a circumpolar constellation. It is important to note that your latitude will determine the constellations that you are able to see. In Saskatoon the latitude is roughly 52 degrees. This means that people in Saskatoon can see some circumpolar constellations and some seasonal constellations. If you were standing on the top of the North Pole, you would only see circumpolar constellations and the North Star would be directly above you. You would see all the constellations rotate around the North Star. In Saskatoon we see the North Star 52 degrees above our northern horizon. If you were standing on the equator, the North Star would be directly on your northern horizon and you would be able to see all the constellations in the northern hemisphere and the southern hemisphere. If Astronomy Reference Book 25

30 you are standing at the equator, all the constellations are seasonal. The following two charts show you the circumpolar constellations and seasonal constellations in the northern hemisphere. These charts are handy because they tell you which constellations you will be able to see year round and which ones you can only see during a particular season. Circumpolar Constellations (we can see these year round) Ursa Major (Big Dipper) Ursa Minor Draco Cepheus Cassiopeia Camelopardalis Seasonal Constellations (we can only see these during particular seasons) Winter Auriga Canis Major Canis Minor Fornax Gemini Horologium Lepus Monoceros Orion Puppis Taurus Spring Bootes Cancer Canes Venetici Centaurus Coma Berenices Corvus Crater Hydra Leo Leo Minor Lynx Sextans Virgo Summer Aquila Capricornus Corona Australis Corona Borealis Cygnus Delphinus Equuleus Hercules Libra Lyra Ophiuchus Scorpius Scutum Serpens Sagitta Sagittarius Telescopium Vulpecula Fall Andromeda Aquarius Aries Cetus Lacerta Pegasus Perseus Pisces Sculptor Triangulum 26 Astronomy Reference Book

31 Navigating Around the Sky In astronomy there are some tips and tricks that are useful when trying to find certain constellations and celestial objects. This section will show you how to find some common constellations and will explain some tips and tricks that are useful when it comes to navigating around the night sky. We ll start by looking at the Big Dipper: Wikipedia, IAU and Sky & Telescope magazine, Roger Sinnott & Rick Fienberg, 2011 Astronomy Reference Book 27

32 Finding the North Star Using the Big Dipper The Big Dipper is very useful for navigation because this constellation can be used to locate the North Star, also known as Polaris. The North Star will stay in the same spot in the sky all year round so if you find the North Star, you will always know which way is north. The two stars that make up the outer edge of the Big Dipper, Merak and Dubhe, always point directly towards the North Star. Once you find the North Star, then you can easily find the Little Dipper, otherwise known as Ursa Minor, the smaller bear. The Little Dipper looks like a smaller mirror image of the Big Dipper. Finding Polaris (the North Star) using the Big Dipper, Wikipedia, NASA, 2009 Finding Arcturus and Spica using the Big Dipper There are two interesting stars that you can easily find using the handle of the Big Dipper. These two stars are Arcturus and Spica. Arcturus is located in the constellation Bootes and is an orange giant star. Spica, although much dimmer than Arcturus, is the brightest star within the constellation Virgo. To find Arcturus, just remember the phrase Arc to Arcturus, then spike to Spica. The arc is referring to the handle of the Big Dipper. Once you find Arcturus by following the arc, then you just need to keep following that path to find Spica. 28 Astronomy Reference Book

33 Arc to Arcturus, then spike to Spica. Astronomy Reference Book 29

34 Using the Summer Triangle The summer triangle is a pattern in the sky that can be seen during the summer months. The summer triangle is formed by connecting three bright stars: Deneb, Altair and Vega. Each of the stars that make up the summer triangle is part of a different constellation. If you can find the summer triangle, then you can easily find the three constellations Cygnus (the Swan), Lyra (the Harp) and Aquila (the Eagle). Deneb makes up the tail of Cygnus, the Swan and the body runs along a line towards Albireo which is the head of the swan. Vega is the third brightest star in the northern hemisphere and is located in Lyra, the Harp: Wikipedia, IAU and Sky & Telescope magazine, Roger Sinnott & Rick Fienberg, Astronomy Reference Book

35 Cygnus, the swan and Lyra, the Harp are two of three constellations that can be found with the Summer Triangle. Altair is the brightest star in the constellation Aquila, the Eagle: Wikipedia, IAU and Sky & Telescope magazine, Roger Sinnott & Rick Fienberg, 2011 Astronomy Reference Book 31

36 How to Find Some Common Constellations Cepheus and Cassiopeia Cepheus and Cassiopeia are circumpolar constellations and they are fairly close to the North Star (Polaris). If you can find the North Star then look for a pattern of stars that almost looks like a house (or an upside down house, depending on your orientation). If you find a pattern that looks like a house, that is Cepheus. Cassiopeia has the shape of a w and is right beside Cepheus. See the star chart at right. Wikipedia, IAU and Sky & Telescope magazine, Roger Sinnott & Rick Fienberg, Astronomy Reference Book

37 Camelopardalis Camelopardalis is a circumpolar constellation and is found in between Ursa Major and Cassiopeia. It is a fairly faint constellation but it takes up a large part of the sky: Wikipedia, IAU and Sky & Telescope magazine, Roger Sinnott & Rick Fienberg, 2011 Astronomy Reference Book 33

38 Perseus Perseus is a useful constellation to locate because within it is a famous double star cluster called NGC 869/844, a beautiful star cluster that is visible even with your naked eye or a pair of binoculars. The Perseus constellation is just below Camelopardalis and borders Andromeda and Auriga. Wikipedia, IAU and Sky & Telescope magazine, Roger Sinnott & Rick Fienberg, Astronomy Reference Book

39 Hercules Hercules contains one of the most well known globular clusters called M13 or the Great Cluster of Hercules. The torso of Hercules is made of four stars and the arms and legs extend out from each of these four stars. To find Hercules, start by finding the constellation Lyra - Vega is a bright star within Lyra that you can look for. Hercules is just to the east of Lyra. The other constellations that border Hercules are Bootes, Draco, Ophiuchus and Corona Borealis. Wikipedia, IAU and Sky & Telescope magazine, Roger Sinnott & Rick Fienberg, 2011 Astronomy Reference Book 35

40 Pegasus and Andromeda Pegasus and Andromeda are constellations that are side by side and appear as if they are connected together. Pegasus borders Cygnus, the Swan so find Cygnus first and then look to the east of Cygnus to find the square of Pegasus. Go to the top left hand star of the Great Square of Pegasus and follow a line of stars to the east, this will take you along the Andromeda constellation. Wikipedia, IAU and Sky & Telescope magazine, Roger Sinnott & Rick Fienberg, Astronomy Reference Book

41 Andromeda contains the closest Galaxy to us called M31 or the Andromeda Galaxy. M31 is visible with your naked eye, but it looks even better with a telescope. Wikipedia, IAU and Sky & Telescope magazine, Roger Sinnott & Rick Fienberg, 2011 Astronomy Reference Book 37

42 Orion Orion is a winter constellation and is located in between Taurus, Auriga and Gemini. A characteristic feature of Orion is the belt that is made up of three bright stars. Below the belt is a vertical line of stars that make up the sword. Orion contains a beautiful emission nebula called M42 or the Orion Nebula which is visible with your naked eye. M42 is located within the sword of Orion. Wikipedia, IAU and Sky & Telescope magazine, Roger Sinnott & Rick Fienberg, Astronomy Reference Book

43 Gemini The two notable stars in Gemini are Castor and Pollux, which make up the heads of the twins. The bodies of the twins extend down from there, taking up a large area of the sky. Gemini lies in between Taurus and Cancer and is easily recognizable in the winter months by locating Castor and Pollux. Wikipedia, IAU and Sky & Telescope magazine, Roger Sinnott & Rick Fienberg, 2011 Bootes Bootes is a spring constellation that is home to one of the brightest stars in the sky, Arcturus. Bootes is surrounded by some prominent constellations such as Ursa Major, Virgo, Canes Venetici and Hercules. In mythology, Bootes is the herdsmen with his hunting dogs (represented by Canes Venetici). His oxen are attached to the rotation axis keeping the skies in perpetual rotation. Wikipedia, IAU and Sky & Telescope magazine, Roger Sinnott & Rick Fienberg, 2011 Astronomy Reference Book 39

44 Chapter 5 The Moon What is the Moon? A moon, also called a satellite, is a relatively small object that is orbiting around a planet. Earth s moon is the fifth biggest moon in the solar system. As we will see, several other planets in the solar system also have moons. On average, the distance between the Earth and the moon is 384,000 kilometres. To give you an idea of its size, the moon is about four times smaller than the width of the Earth. You could fit the moon inside the Earth about 50 times before filling it up. It is suspected that the moon formed about 4.5 billion years ago through a catastrophic collision with an asteroid and the proto-earth. Then, over time, the Earth-Moon system was formed: Artists rendition of moon formation, Wikipedia, NASA, 2009 Earth-Moon system captured by Galileo spacecraft in Astronomy Reference Book