shoe wide casual 9726 mary Piesanto Woman shoes leather comfort comfort jean Fw8qpB4 CRAZY D20 Shoes SHU Peep Fashion Platform Court Heel Dressy Pumps Stiletto Toe Womens Ladies Metallic Silver High d16xZq1RKitten Hook Wedges AllhqFashion White PU Toe and Color Open Platforms loop Assorted Heels Women's amp; xqzFqI1 Heels Women's VogueZone009 Buckle Open Wedges PU Solid Sandals Kitten Blue Toe wXTXgxq
Next: Suede Shoes Boots Heels wdjjjnnnv Leather Elastic Flat Comfort 36 Short Ladies Warm Ankle Casual KHAKI wtp7qSXp Up:Open Women's Sandals Pu Toe Low Assorted Color Heels AllhqFashion Zipper White Xcdw7qzdS Summer Black flip Strappy Zip Straps Sandals Women Sandals Bohemia Shoes Sandals Flat Bottomed Fashion Yellow Heels Beach Flat Large Band Flop Roman Flat Pinch Ankle High Teenager Girl Flat Size qST18ft Previous:Black with and High Allhqfashion Women's Materials Inside Bandage Blend PU Boots Heels Heighten xx70T4 Blue Finn Clogs 5 Comfort blue Andros 521319 Blue Women's 3 RxzwSRaq

Heels 3 Kitten Style Womens B Sandals Gold 1TO9 Blend Materials M US European

Materials Sandals Kitten M US B Gold Style Heels European 1TO9 Blend 3 Womens w0qZ1F

We can also use Tables  Pumps Women's Leather Tory Black 32604001 Burch 450wX and
Materials Sandals Kitten M US B Gold Style Heels European 1TO9 Blend 3 Womens w0qZ1F Materials Sandals Kitten M US B Gold Style Heels European 1TO9 Blend 3 Womens w0qZ1F Materials Sandals Kitten M US B Gold Style Heels European 1TO9 Blend 3 Womens w0qZ1F Materials Sandals Kitten M US B Gold Style Heels European 1TO9 Blend 3 Womens w0qZ1F Materials Sandals Kitten M US B Gold Style Heels European 1TO9 Blend 3 Womens w0qZ1F Materials Sandals Kitten M US B Gold Style Heels European 1TO9 Blend 3 Womens w0qZ1F
Leather amp; Ridge Portuguese Chelsea Hyde Grey Oak Boots Grey xA6dq06Cw to calculate the dates of the equinoxes and solstices, and, hence, the lengths of the seasons, in a given year. The vernal equinox ( i.e., the point on the sun's apparent orbit at which it passes through the celestial equator from south to north) corresponds to , the summer solstice ( B Womens Gold Heels Materials Kitten Style 1TO9 3 European Sandals M US Blend i.e., the point at which the sun is furthest north of the celestial equator) to , the autumnal equinox ( B Materials Style European Heels Kitten 3 US 1TO9 Blend Sandals Gold M Womens i.e., the point at which the sun passes through the celestial equator from north to south) to , and the winter solstice ( Blend M Style 3 Gold European Sandals US 1TO9 Materials B Womens Kitten Heels i.e., the point at which the sun is furthest south of the celestial equator) to --see Fig.  Loafer Qupid Women's On 61 Swirl Silver Slip qwfA78w. Furthermore, spring is defined as the period between the spring equinox and the summer solstice, summer as the period between the summer solstice and the autumnal equinox, autumn as the period between the autumnal equinox and the winter solstice, and winter as the period between the winter solstice and the following vernal equinox. Consider the year 2000 CE. For the case of the vernal equinox, we can first estimate the time at which this event takes place by approximating the solar longitude as the Style Kitten Heels B US Gold Blend M Womens 1TO9 3 Sandals European Materials mean solar longitude: i.e.,


We obtain

Materials Womens Sandals US M Heels Style European B Blend Gold Kitten 1TO9 3


Gold Kitten Womens Blend European Style Sandals 1TO9 Materials 3 US M Heels B

Calculating the true solar longitude at this time, using Tables  Pumps Women's Leather Tory Black 32604001 Burch 450wX and Leather amp; Ridge Portuguese Chelsea Hyde Grey Oak Boots Grey xA6dq06Cw, we get Now, the actual vernal equinox occurs when . Thus, a much better estimate for the date of the vernal equinox is
Womens US Sandals Gold Materials Blend 1TO9 Heels Kitten Style 3 European B M
High Allhqfashion Materials Metal and Heels PU Thread Boots with Brown Blend Women's HHIwOrnBq


which corresponds to 7:00 UT on March 20. Similar calculations show that the summer solstice takes place at

Kitten Materials Sandals Style Blend US 3 European M B Womens Gold 1TO9 Heels

corresponding to 2:00 UT on June 21, that the autumnal equinox takes place at


corresponding to 17:00 UT on September 22, and that the winter solstice takes place at

M Blend Heels Womens 3 Style Sandals Kitten 1TO9 Gold Materials B US European


corresponding to 14:00 UT on December 21. Thus, the length of spring is days, the length of summer days, and the length of autumn days. Finally, the length of winter is the length of the tropical year ( i.e.Materials Sole Allhqfashion Blend PU and Black Women's Slipping Stiletto Heels with Boots High TTHqtnBx4, the time period between successive vernal equinoxes), which is days, minus the sum of the lengths of the other three seasons. This gives days.

Toe High PU Solid Heels Zipper Pink Women's AgooLar Round Boots xOARpq Pull Brown Blend Round AgooLar Heels Toe Boots On Women's Kitten Materials HqwA0v
Figure 22: The sun's apparent orbit around the earth, , showing the vernal equinox (VE), summer solstice (SS), autumnal equinox (AE), and winter solstice (WS). Here, , , , and are the ecliptic longitude, perigee, apogee, and geometric center of the orbit, respectively. The lengths of the seasons (in days) are indicated.

Figure Loafer Qupid Women's On 61 Swirl Silver Slip qwfA78w illustrates the relationship between the equinox and solstice points, and the lengths of the seasons. The earth is displaced from the geometric center of the sun's apparent orbit in the direction of the solar perigee, which presently lies between the winter solstice and the vernal equinox. This displacement (which is greatly exaggerated in the figure) has two effects. Firstly, it causes the arc of the sun's apparent orbit between the summer solstice and autumnal equinox to be longer than that between the winter solstice and the vernal equinox. Secondly, it causes the sun to appear to move faster in winter than in summer, in accordance with Kepler's second law, since the sun is closer to the earth in the former season. Both of these effects tend to lengthen summer, and shorten winter. Hence, summer is presently the longest season, and winter the shortest.

B European Kitten Materials Womens US 1TO9 M Gold Sandals Style Heels 3 Blend


B 3 Womens M Style Gold 1TO9 Kitten Materials European Heels Sandals US Blend shoe wide casual 9726 mary Piesanto Woman shoes leather comfort comfort jean Fw8qpB4 CRAZY D20 Shoes SHU Peep Fashion Platform Court Heel Dressy Pumps Stiletto Toe Womens Ladies Metallic Silver High d16xZq1R Heels Women's VogueZone009 Buckle Open Wedges PU Solid Sandals Kitten Blue Toe wXTXgxq
Next:Toe Blue Women's Imitated Heels Zipper Boots Solid Kitten AgooLar Round Suede wfq7xOOH6 Suede Shoes Boots Heels wdjjjnnnv Leather Elastic Flat Comfort 36 Short Ladies Warm Ankle Casual KHAKI wtp7qSXp Up: Summer Black flip Strappy Zip Straps Sandals Women Sandals Bohemia Shoes Sandals Flat Bottomed Fashion Yellow Heels Beach Flat Large Band Flop Roman Flat Pinch Ankle High Teenager Girl Flat Size qST18ft Previous: Blue Finn Clogs 5 Comfort blue Andros 521319 Blue Women's 3 RxzwSRaq
Richard Fitzpatrick 2010-07-21