Park School Astronomy Club

Ptolemaic Universe (geocentric) http://astro.unl.edu/naap/ssm/animations/ptolemaic.swf The most important things to get out of this are: - Epicycles were a very useful way to (wrongly) explain why retrograde motion happened with planets. - Precession (the wobbling of the Earth) causes us to have different North Stars (or no North Star) at various points over the course of thousands of years.  Thus, star maps are not accurate after several hundred years.  However, this was not understood until the time of Newton and others. Nicolaus Copernicus, 1473 - 1543 http://astro.unl.edu/naap/ssm/animations/configurationsSimulator.html Galileo Galilei, 1564 - 1642 Galileo and his telescope: moon craters moons of Jupiter phases of Venus "rings" of Saturn stars in the Milky Way sunspots Speaking of sunspots: http://galileo.rice.edu/sci/observations/sunspot_drawings.html Johannes Kepler, 1571-1630 - his laws (shown below) are based o

Celestial Sphere - points to know: - Both Equinoxes - Both Solstices Celestial north Celestial south Ecliptic Celestial equator Coordinates : On Earth: Longitude half-circle lines from North to South pole Zero longitude runs through the site of the Royal Greenwich Observatory in England - the Prime Meridian (0 degrees long.) Number of degrees east or west of the PM Latitude Full circle lines parallel to the equator (0 degrees latitude) + or - 90 degrees corresponds to the poles International Date Line (IDL) Near or along 180 degrees longitude line, through the Pacific Ocean As we travel eastward around the globe, the hours get later roughly each 15 degrees (a time zone). When we cross the IDL, we go BACK one day. This keeps only 24 hours on the Earth at a time. In the Sky: Celestial Equator - imaginary line above the Earth's equator Right Ascension (RA) Celestial analog of longitude (both measure east-west) Measured in hours (each hour of RA equals 15 degrees) along the celestial

Celestial Sphere Celestial sphere sites The first site allows you to simulate the apparent motion of the Sun around the Earth for any day of the year (and location).  It's really cool to play around with. http://astro.unl.edu/naap/ motion3/animations/sunmotions. swf http://www.astronomynotes.com/ nakedeye/csph1t5.htm http://www.astronomynotes.com/ nakedeye/s4.htm > The analemma - the "apparent" path of the Sun around the Earth

http://astro.unl.edu/naap/ motion3/animations/sunmotions. swf On the size of things: http://htwins.net/scale2/ http://scaleofuniverse.com/ http://xkcd.com/482/ http://xkcd.com/1331/ This is just cool. http://workshop.chromeexperiments.com/stars/ http://www.youtube.com/watch? v=8yCzzTkDSMo Jack Horkheimer (R.I.P.), for your interest.  Not related to the Celestial Sphere stuff.