6A Constellations Objectives

1. 6A ConstellationsObjectives • What is a constellation? • What is a circumpolar constellation? • Around what point do all the stars rotate? • How do you locate Polaris? • Name four things that make stargazing more comfortable?

2. Introduction to Constellations

3. Constellations • Constellations are named patterns of stars • All societies created them • The classical -- "ancient" -- constellations that populate our sky began in the lands of the middle east thousands of years ago, their origins largely lost to time

4. Constellations • They passed through the hands of the ancient Greeks, who overlaid them with their legends and codified them in story and verse • During Roman times they were assigned Latin names

5. Constellations • The 48 ancient constellations single out only the bright patterns • From around 1600 to 1800, post-Copernican astronomers invented hosts of "modern" constellations from the faint stars that lie between the classical figures from pieces of ancient constellations, and from the stars that occupy the part of the southern sky that could not be seen from classical lands

6. Constellations • In the early twentieth century, the International Astronomical Union (IAU) adopted 38 of the modern constellations and drew rectangular borders around all 88 • The IAU also adopted three-letter abbreviations for all the constellations

7. Constellations • Many of these contain informal constellations, or "asterisms," that are often the first to be learned • Ursa Major holding the "Big Dipper" and so on

8. Constellations • Other asterisms, like the Winter Triangle, cut across constellation boundaries • Some constellations look like what they are supposed to represent, but most do not • Constellations, both ancient and modern, are generally meant to honor and represent, not to portray

9. Constellations • The constellations play an important role in modern astronomy • They bring order to the sky by dividing it into smaller segments, providing a base for naming celestial objects

10. The Night Sky People have watched the night skies for millions of years. Some just out of curiosity. Some out of boredom. Some looking for portents, either good or bad. However, the one thing that they all saw was that there was a pattern in the way the stars revolved around the heavens.

11. The Night Sky You need only to look up for a few hours to begin to see these same patterns yourself. Like the Sun, stars rise in the east and set later in the west. Planets follow this same pattern unless they are in a retrograde period, though these periods are not especially common.

12. What You Need for Stargazing Complete darkness-Don’t laugh, it’s not that easy to find. Rural areas are slowly being urbanized, bringing their lights with them. Light pollution is a real problem.

13. What You Need: Darkness Darkness means keeping up with the phases of the moon, too. When the moon is waxing past half full, it’s quite hard to see.

14. What You Need: Flashlight You can bring a flashlight! There’s one problem here though. It takes your eyes about 20-30 minutes to get acclimated to the dark. Your pupils aren’t fully dilated until then, so a regular flashlight will never do. Your eyes will have to get acclimated every time you turn it on. To prevent this, your flashlight should have a red gel to protect your eyes. Red saran wrap with a rubber band works great .

15. What You Need: Binoculars Binoculars don’t have to be very strong to give you a much better, brighter view of the stars. Binoculars have the ability to gather light even at low magnifications. Even 4X ones will make a marked difference in the detail you can see.

16. You’ll be happy to know that the best time to look at stars is the least popular time of year to be outside, the winter. So, dress warmly. Remember that the nights are longer in the winter. What You Need: Warm Clothes

17. Vocabulary • Celestial Sphere • Celestial Equator • Right Ascension • Declination • Zenith • Nadir

18. Finding Polaris and Why Polaris (or the North Star) is where you want to start. Because Polaris is aligned with the Earth’s axis of rotation, it remains fixed, with all the other planets and stars appearing to move around it.It is the one star that remains fixed at all times.

19. Getting Oriented Yea, you have to find north. It’s where Polaris (or North Star) is. You can use a compass, a major interstate or other landmarks that you are familiar with to get oriented toward the north.

20. Figuring the Angle Once you’ve decided where north is (right ascension), face in that direction. Next you have to figure declination (up and down). Extend your arm and make a fist. Put the bottom of your fist on the horizon. The top of your fist is about 80 higher. Place your other fist on top of your first. You’ve now measured 160 up from the horizon. Polaris is located between 250 and 300 above the horizon. Polaris is faint, so look carefully!

21. Another Way to Find Polaris If all that compass making and angle crap is just too complicated, there is another way to find Polaris. Find the Big Dipper (not a constellation). Most people recognize this asterism. The two stars that form the front of the cup of the dipper define a line pointing to Polaris.

22. The Big Dipper

23. The Stars Circling Polaris

24. Now That You’re Oriented, It’s Time to Explore. You’re pointed in the right direction, but what now. Stars and constellations move constantly and seasonally. What am I looking for? What you need is a star map.