Black 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.

Blue Star Chart The small brass ring in the middle is the location of the North Star. The “dotted circle” around the North Star is the ecliptic where the sun is found on different days. Note that the ecliptic is a circle, but the North Star is not at it’s center but is offset. The solid circle is the equator – what would be overhead at the equator on different days and is 90o from the North Star.

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 solid circle on the previous slide or the pink circle on the next slide). At the North pole, you would not be able to see any of the starts outside the solid line.

Star Chart Note that the constellations of the zodiac (e.g. Leo, Sagittarius, and Gemini,) are found along the “railroad tracks”, i.e., along the ecliptic. In fact, it is that location along the ecliptic that makes these constellations special.

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. Philadelphia, Indianapolis, Kansas City, Salt Lake City, and Northern California have a latitude of about 40o N) 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.

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.

Positions of the sun Sun at noon on Dec. 21 in Sagittarius. Compare this position to that of the sun on June 21 on the next slide.

Positions of the sun Sun at noon on June 21. Note that the sun appears in Gemini and above (to the North of) Orion. The sun is much higher in the sky in summer than in winter.

Positions of the Sun Here we see the sun on the Western horizon (sunset) in in Gemini on June 21 a little after 7 PM CST (or 8 PM CDT). Notice that the sun sets well North of West.

Positions of the Sun Compare the position of the setting sun in Sagittarius on Dec. 21 - it happens about 4:30 PM and is quite a bit South of due West.

Sun on Dec. 21 at noon Notice how low in the Southern sky the sun is at noon on December 21.

Sun on June 21 Compare where the sun is at noon on June 21 – how high it is in the sky.

Sunrise on December 21 Notice how far South of East the sun rises on December 21. (Recall that East is on the left instead of the right when looking down at the star chart.)

Sunrise on June 21 Notice how far North of East the sun rises on June 21!

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.

Positions of the sun Note that in June, the sun is in Gemini, but in July it moves toward Cancer and then in August it moves toward Leo. The sun moves across the sky from East to West, but it moves through the constellations of the zodiac from West to East!