2/5/09 Announcements • Observing lab: Constellations and Star Wheel – Due Feb 12 • Observing lab: Motion and Phases of the Moon – Due Mar 17 or Apr 14 In Figure 1 the position of Star B at 6 pm has been identified for you. Which position in Figure 2 corresponds to the identified location of Star B at 6 pm? a) 1 b) 2 c) 3 d) 4 Approximately what time would Star B arrive at the position indicated by the big red arrow? a) 6 pm b) Midnight c) 6 am d) noon 1 2/5/09 At what time will Star B be located high in the Northwestern sky? a) 4 am b) 10 am c) 2 pm d) 7 pm e) 1 am If you were able to see the motion of star B be at Noon, over a period of 15 minutes what direction would it appear to move? a) west (to the left) b) east (to the right) c) south (out of the page) d) away from the horizon (up) e) toward the horizon (down) Your view of the stars depends on your latitude In Cape Town, At the North Pole (90° N) South Africa (34° S) 2 2/5/09 Star Paths in Northern Hemisphere • Stars rise at an angle to the horizon, up and south • Some stars are circumpolar Star Paths in Southern Hemisphere • Stars rise at an angle to the horizon, up and north • Some stars are circumpolar Star Paths at North Pole • Polaris is overhead • Stars go parallel to the horizon • All stars are circumpolar 3 2/5/09 Star Paths at Equator • Stars rise straight up from horizon • No circumpolar stars The altitude of the celestial pole in your sky is equal to your latitude You are stranded on a desert island. You located the pole star Polaris. It is 17 degrees above the northern horizon. What is your latitude? a) 73 degrees south. b) 17 degrees north. c) 73 degrees north. d) 17 degrees south. 4 2/5/09 The constellations today • Today we have 88 official constellations – 48 ancient – 40 modern – Completely fill the sky • A constellation now represents a section of the sky – Any star within the region belongs to that constellation Asterisms: Unofficial constellations • The sky also contains less formally defined groupings known as asterisms – Some asterisms are part of a larger constellation – Some asterisms contain stars from several constellations Use the Big Dipper in the northern sky to find constellations during spring evening 5 2/5/09 Use the Summer Triangle to find constellations during summer evenings Use the Winter Triangle to find constellations in the winter evening 6 .