Today in Space News: Space.com story More info from NASA Credit: NASA/JPL-Caltech/MSSS
Study Points (marked with *) Describe positions of stars, Moon, Sun on the sky using direction and altitude. Do this when looking at the sky or a star chart. Measure altitudes using the fist method. Define and use horizon and zenith. Know how many degrees between horizon and zenith. Describe how to correctly hold and orient a star chart and use it to find stars and constellations. Practice star hopping to locate stars and constellations. Explain why the date and time are included on star charts and what causes each to change. State the magnitude scale for stars. Given a star s magnitude, identify if it is bright or faint. Define rotation and revolution as used by astronomers. Use them correctly when describing the motion of Earth, other planets, Sun and Moon. Identify and use the correct color light to maintain dark adaptation when stargazing.
Star Gazing Star Gazing techniques and tips: how to get the most out of looking up at the stars (slideshow on class website mctcteach.org) Show 2 flashcards to me.
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 Star Chart or Sky Map Phases of the Moon Sunrise Sunset ISS Detector (International Space Station) NASA Lots of other star apps out there
Positions in the sky - Direction How can you find N, S, E, or W?
Positions in the sky Direction* How can you find N, S, E, or W? Compass Phone/GPS/Car Map North Star = Polaris
Positions in the sky Altitude* Altitude is an angle in degrees* Measured from horizon or zenith Can also be measured from another star or constellation Horizon intersection of Earth and sky* About eye level, 0 degrees* Zenith point in sky directly overhead* 90 degrees, straight up* Halfway between horizon & zenith = 45 degrees Fist Method: Extended fist is ~10 degrees* Exercise (Height of building from ground)
Star Charts Print current month of the Sky Map if you missed lecture: http://skymaps.com/downloads.html Find N, S, E, W Orienting the star chart (how to hold it) Hold the star chart so that the direction you are facing is closest to you.* If you face N, hold N down on the chart, closest to you. Directions are printed around the circular edge of the star chart
From Star Chart to Sky Note where constellation is on map Use direction and altitude* Use fist method to find it in sky Examples Polaris Venus
Star Hopping* Estimate direction and altitude (degrees) when moving from one star to another star* Ursa Major to Ursa Minor (Polaris), use pointing stars 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 Summer/Fall: Deneb (NE) to Altair (southern tip of Summer Triangle) points to bottom left of The Teapot handle Winter/Spring: Orion s belt, left to Sirius, right to Aldebaran (Taurus) and Pleiades
Greek Letters on star charts Brightest stars in that constellation Alpha ( α ), brightest Beta ( β ), 2 nd brightest Gamma (γ ), 3 rd brightest Delta ( δ ), 4 th brightest Example: Deneb in Cygnus is Alpha Cygni and is the brightest star in Cygnus
Why is the TIME on the star chart?*
Why is the TIME on the Earth s Rotation * star chart?* Displays different constellations throughout the night Rotation is spin around an axis* 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?*
Why is the DATE on the star chart?* Earth s Revolution...* Displays different constellations throughout the year Revolution is orbital motion* Revolve = Orbit
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 1 st magnitude is 100 times brighter than the 6 th magnitude Originally based on Polaris (apparent magnitude = 2) Later extended to negative numbers The smaller the number, the brighter it is.* -1 (negative 1) is brighter than 2 (positive 2) The larger the number, the fainter (dimmer) it is.* Example: Sirius is the brightest star in the sky and has an apparent magnitude of -1.5
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 Pupil shuts down quickly in response to white light but not to red light. Use red flashlights for night star viewing so that you do not wreck dark adaptation of your eyes.*
Dark Adaptation 1. Show red covered flashlights 2. Turn lights off and use curtains 3. Show colors displayed around the room 4. 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
Eye Blind Spot Cross-dot demo of blind spot (draw on paper) http://www.optics4kids.org/getattachment/13cb7b00-117a-4e69-9d5d- 35ad7d949199/Optical-Illusions.aspx
Observation Projects 100+ points of observations available but only a max of 100 points will be given. Currently at 115 points but more might be added later. Earth-Sun Scaling Start: Aug. 30 Due: Sep. 11 10 points Telescope Start Sep. 4 Due Dec. 18 25 points Star Gazing Start Sep. 4 Due Dec. 18 25 points Moon Craters Start Sep. 4 Due Dec. 18 10 points
Homework Continue flashcards of STUDY POINTS If you haven t shown me your flashcards yet, do so now. Complete the first D2L Quiz about Scaling and Estimating. Work on the Earth-Sun Scaling Observation due Sep. 11 Work on Telescope, Stargazing, and Moon Craters Observations due Dec. 18 Lab arrive this week with the necessary materials