Transcript Star Gazing
Star Gazing • Star Gazing techniques and tips: how to get the most out of looking up at the stars (powerpoint and notes on class website) • Show 2 flashcards/notecards to me. • Email me if you haven’t yet stating, “I found the class website.” Details in the notes from last Tuesday, Jan. 13 • If you haven’t given me a code to use for your grades on the class website, see Raquel. Sky Software • • • • • Starry Night College ($30) SkyX Stellarium (free) Celestia (free) Google Earth and Google Sky https://www.google.com/sky/ (free) Sky Phone Apps (all free) • • • • • • Google Sky Map Phases of the Moon Sunrise Sunset ISS Detector (International Space Station) NASA Lots of other star apps out there Positions on the sky - Direction • How can you find N, S, E, or W? – Compass – Phone/GPS/Car – Map – North Star = Polaris Positions on the sky - Altitude • Horizon – intersection of Earth and sky • Zenith – point in sky directly overhead – 90 degrees – Halfway: 45 degrees • Fist Method: Extended fist is ~10 degrees Exercise (Right angle in classroom) Exercise (Height of building from ground) Star Charts • Print Sky Map if you missed lecture: • http://skymaps.com/articles/n1409.html • Finding N, S, E, W • Orienting the star chart – If you face N, hold N down on the chart, closest to you. From Star Chart to Sky • Note where constellation is on map (direction and altitude) • Use fist method to find it in sky • Examples – Cygnus – Polaris – Mars Star Hopping • • • • Ursa Major to Ursa Minor (Polaris) Ursa Major: arc to Arturus (in Bootes) Cassiopeia: left V eats Polaris Cassiopeia: right V points to Andromeda (only galaxy visible to the naked eye); then Andromeda curves to Great Square of Pegasus • Deneb (NE) to Altair (southern tip of Summer Triangle) points to bottom left of The Teapot handle Greek Letters on star charts • • • • • Brightest stars in that constellation Alpha ( α ) Beta ( β ) Gamma (γ ) Delta ( δ ) • Example: Deneb in Cygnus is Alpha Cygni Why is the TIME on the star chart? • Earth’s Rotation… – Displays different constellations throughout the night • In the northern hemisphere, the stars appear to rotate around Polaris, the North Celestial Pole. Polaris, the north star, with all of the stars moving around it. The star trails are from the Earth’s rotation. http://apod.nasa.gov/apod/ap091128.html Why is the DATE on the star chart? • Earth’s Revolution... – Displays different constellations throughout the year Planisphere - North on front - South on back For more instructions about how to use your planisphere: http://astronomy.s ierracollege.edu/C ourses/Astronomy 02/Planisphere.ht m • 12 Constellations of the Zodiac seen throughout the year because of Earth’s revolution. • The zodiacal constellations are located along the Sun’s path on Earth (Ecliptic). • The Ecliptic is also the plane of Earth’s path around the Sun. http://lifeng.lamost.org/courses/astrotoday/CHAISSON/AT301/HTML/AT30103.HTM Apparent Visual Magnitude • Hipparchus – 1 (first magnitude) bright to eye – 2 (second magnitude) fainter – …6 (sixth magnitude) faintest to eye – 1st magnitude is 100 times brighter than the 6th magnitude – Originally based on Polaris (app. mag. = 2) – Now extended to negative numbers – Example: Sirius, brightest star in the sky has magnitude -1.4 Dark Adaptation In dark, eye pupil enlarges to let in more light. In sun, pupil shrinks to keep out light. Exercise with dim lights Dark Adaptation • When star gazing, eye pupil needs to open up (~15 minutes) • Eyes have cones and rods (photoreceptors) – Cones see color & adapt to darkness quickly – Rods take 10-30 minutes to adapt to darkness • It shuts down quickly in response to white light but not to red light. • Therefore use red flashlights. Dark Adaptation 1. 2. 3. 4. Show red covered flashlights Turn lights off and use curtains Show colors displayed around the room Color differentiation disappears after 10 minutes (color is from cones) 5. About 15 minutes in, rods take over; no color and now see light trails (sparklers); laser demo Dark Adaptation Blind Spot • Little dipper & Polaris example http://www.optics4kids.org/getattachment/13cb7b00-117a-4e69-9d5d-35ad7d949199/OpticalIllusions.aspx (draw Little Dipper constellation on whiteboard) Eye Blind Spot • Cross-dot demo of blind spot (draw on paper) http://www.optics4kids.org/getattachment/13cb7b00-117a-4e69-9d5d35ad7d949199/Optical-Illusions.aspx Sunset Part 1 Observation • Jan. 20 to Feb. 12 to complete • Take a picture of the sunset with 30o open region to the right of the sun (spring sunset). Use fist method (arm outstretched) to measure 30o (3 fist lengths) to the right/north of sunset now. • Specific directions on website for what you need to write down. • Turn in the picture with details listed in the calendar sunset observation file. • Part 2: Apr. 2 to Apr. 28 to complete the 2nd picture in EXACT SAME SPOT Homework • See today’s notes • http://mctcteach.org/astronomy/ • Show 2 flashcards/notecards to me. • Email me if you haven’t yet stating, “I found the class website.” Details in the notes from last Tuesday, Jan. 13 • If you haven’t given me a code to use for your grades on the class website, see me.