Seasons • Tilt of Earth’s Axis • Special dates • Observable results • Precession • Astrology’s flaws
Seasons • What do you think causes the seasons? Draw a picture. • When it’s Summer here, what season is it in Europe? • When it’s Summer here, what season is it in South America? • When it’s Summer here, what season is it in Australia?
NOT caused by Distance • Distance varies very little, orbit nearly circular • Both Northern and Southern Hemispheres would have the same seasons but they don’t. • Jan 3 actually day we’re closest to Sun
http://www.definity-systems.net/~apw/astro/images/perihelion.jpghttp://www.definity-systems.net/~apw/astro/images/perihelion.jpg
23.5º Tilt of Earth’s axis
Observable Effects • How directly the sunlight hits Earth • Length of the day • Where in the sky the Sun appears • Which constellations the Sun seems near, and which we can see at night
Coordinates on the Celestial Sphere • Right Ascension (RA, ) • East/West • Similar to Longitude on Earth • Measured in Hours, Minutes, Seconds • Declination (Dec, ) • North/South • Similar to Latitude on Earth • Measured in Degrees, Minutes, Seconds
Special Days • Vernal Equinox, March 21 • Summer Solstice, June 21 • Autumnal Equinox, September 21 • Winter Solstice, December 21
Special Days
Special Days
Astrology ≠ Science • Some parts are testable and have been proven WRONG • Other parts are NOT falsifiable (vague descriptions that could be true for anyone) • But, if we think of horoscopes as a flawed model, we can use the flaws to teach science!
Ecliptic • The path the Sun appears to take through the sky throughout the year. • The actual path (orbit) the Earth takes around the Sun.
Zodiac • The band of constellations that the Sun appears to pass through as it travels along the ecliptic throughout the year
Zodiac • The band of constellations that the Sun appears to pass through as it travels along the ecliptic throughout the year • Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpius, Ophiuchus, Sagittarius, Capricorn, Aquarius, Pisces
Other names from Zodiac • Tropics of Cancer / Capricorn • Arctic / Antarctic Circles • First Point in Aries (Vernal Equinox)
Use the celestial sphere model to find the constellation the Sun is in on your birthday.
Precession • Tilt stays constant, but direction changes
Precession • Pole star currently Polaris, slowly changes • The Sun is not necessarily in the correct constellation on your birthday • “First point in Aries” (Vernal Equinox) is moving towards Aquarius • “The dawning of the Age of Aquarius”
Moon Phases • What are the Moon phases? Draw pictures. • What causes Moon phases? Draw a picture. • What causes an eclipse? • Does an eclipse occur every month? Why or why not?
Bibliography • http://calgary.rasc.ca/images/radec_celestial_equator.gif • http://www.mogi-vice.com/Scaricamento/Coordinate-celesti-anteprima.jpg • http://astro.wsu.edu/worthey/astro/html/im-sky/cel-sphere-2.gif • http://home.earthlink.net/~room6a/Clips/celestial07.JPG • http://cnx.org/content/m11932/latest/g_telescope.gif • http://www.astromax.org/planets/images/distglow-Moon5.jpg • http://astronomyonline.org/SolarSystem/Images/Jupiter/FromTelescope.jpg • http://solarsystem.nasa.gov/multimedia/gallery/Galilean_Moons-browse.jpg • http://www.eso.org/public/outreach/eduoff/vt-2004/Background/Infol2/vt2004-if9-fig5.jpg • http://lpc1.clpccd.cc.ca.us/lpc/harpell/images/Venus_phases_sketch.jpg • http://www.acaoh.org/images/club/Anderson_Jim/Saturn-2.jpg • http://www.solarviews.com/raw/sat/saturn.gif • http://www.gsfc.nasa.gov/gsfc/spacesci/pictures/soho/sunspot032901.gif • http://courses.nnu.edu/ph106wj/images/Copernicus_heliocentric.jpg • http://www.astro.keele.ac.uk/~rdj/planets/images/planet_solarsystem.gif • http://www.physicalgeography.net/fundamentals/images/world_time2.gif • http://www.divulgence.net/AxialTilt.jpg • http://cseligman.com/text/sky/summersolstice.jpg • http://www.eas.slu.edu/People/CEGraves/Eas138/fg02_04.jpg • http://www.physics.hku.hk/~nature/CD/regular_e/lectures/images/chap03/seasons.gif • http://www.astronomynotes.com/nakedeye/sunpaths.gif • http://domeofthesky.com/clicks/images/scorpius2.jpg • http://www.mt.net/~watcher/ophiuchus.jpg • http://www.ianridpath.com/startales/image/Sagittarius2.jpg • http://www.astro.virginia.edu/~mnc3z/images/astro121/precession.gif • http://www.pfm.howard.edu/astronomy/Chaisson/AT401/IMAGES/AACHCIU0.JPG • http://cse.ssl.berkeley.edu/img/zodconst.gif
