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Star Chart

Star Chart. The small brass ring in the middle is the location of the North Star. The “railroad tracks” around the North Star are the positions of the sun at different days and form the ecliptic. Note that the ecliptic is a circle, but the North Star is not at it’s center but is offset.

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Star Chart

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  1. Star Chart The small brass ring in themiddle is the locationof the North Star. The “railroadtracks” aroundthe North Starare the positionsof the sun atdifferent days andform the ecliptic. Note that the ecliptic isa circle, but the NorthStar is not at it’s center but is offset.

  2. Star Chart The previous picture, if lifted above your head, is what the sky would look like if you were at the North pole. We could only see to the horizon which would be a circle centered on the North Star that would extend to about 2/3 of the radius in the picture (the pink circle on the next slide).

  3. Star Chart Note that the constellations ofthe zodiac (e.g. Leo,Sagittarius,and Gemini,) arefound alongthe “railroadtracks” (alongthe ecliptic). Infact, it is that locationalong the ecliptic that makes these constellationsspecial.

  4. Star Chart The stars seem to circle around the North Star with a period of just under 24 hours. If we are at some other location in the Northern Hemisphere, our zenith (point straight overhead) would move. When we put the flap of the star chart down as we do in the next slide, we see what the sky would look like from a latitude of about 40 degrees North. (Memphis has a latitude of 35 degrees North.) Scroll around to see more of the chart. If you match up the time of day with the day of the year, this is the way the sky will look like at that time on that day.

  5. Star Chart - directions You may have noticed that the North direction is at the top of the picture as usual, but that the East direction was on the left rather than the right. This is because the chart is to be used above your head rather than down on the desk. If you lift the chart above your head and point the North arrow toward the North, you will find that the East direction does match the East marking on the chart.

  6. Positions of the sun Sun at noonon Dec. 21in Sagittarius. Compare thisposition tothat of the sun on June21 on thenext slide.

  7. Positions of the sun Sun at noonon June 21. Note that thesun appearsin Gemini and above (tothe North of)Orion. The sun is muchhigher in thesky in summerthan in winter.

  8. Positions of the Sun Here we seethe sun onthe Westernhorizon (sunset) in in Gemini on June 21a little after7 PM CST. Notice that thesun sets wellNorth of West.

  9. Positions of the Sun Compare theposition ofthe setting sunin Sagittarius on Dec. 21 -it happens about 4:30 PM and is quite a bitSouth of dueWest.

  10. Motions of the Sun If you play with the star chart, you will see that in the winter months, the sun rises South of East just like it sets South of West. You will also see that in the summer months the sun rises North of East just like it sets North of West. In the summer, the sun is in the sky longer and is also higher in the sky than in winter.

  11. Positions of the sun Note that inJune, the sunis in Gemini,but in July itmoves towardCancer and then in August it movestoward Leo. The sun moves acrossthe sky from Eastto West, but itmoves through theconstellations of the zodiac fromWest to East!

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