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钗谈
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1 Local Horizon and Sundials 本地地平圈与日晷 Rosa M. Ros International Astronomical Union Technical University of Catalonia, Barcelona, Spain 国际天文联合会加泰罗尼亚理工大学 ( 巴塞罗那, 西班牙 )

2 Goals Understand the diurnal movement of the Sun 理解太阳的周日视运动 Understand the annual movement of the Sun 理解太阳的周年视运动 Understand the movement of the celestial sphere 理解天球运动 Understand the construction of sundials 理解日晷的构造

3 The Earth rotates and moves 地球的自转与公转 rotation (day / night) 自转 ( 白天 / 晚上 ) orbital position (seasons) 在轨位置 ( 季节 )

Model: Four Earth spheres with the Sun (a

4 Model: Four Earth spheres with the Sun (a bulb) in the middle. 模型 : 四个地球仪和中间的太阳 ( 灯泡 ) The line from the center of the Sun to the center of the Earth makes a 23 angle with the ground (which represents the plane of the Equator). 太阳中心与地球中心的连线与地面的夹角为 23 ( 地面象征赤道面 )

5 º: 北半球的夏季南半球的冬季 position C: Sun to -23.

5 position A: Sun to º: summer in the northern hemisphere winter in the southern hemisphere 位置 A: 太阳 º: 北半球的夏季南半球的冬季 position C: Sun to º : winter in northern hemisphere summer in the southern hemisphere 位置 C: 太阳 º: 北半球的冬季南半球的夏季

6 Rotation and celestial movements of day and night 自转与昼夜天体运行 Not the same as seen from inside or outside 从天球的内部和外部看是不同的

7 Celestial sphere from outside 从外面看天球

8 ... it seems that everything is controlled 看上去一切都尽在掌握

9 but after class,... he is disconcerted 但下课之后, 他就费解了

10 All schools have an "Astronomy Laboratory 任何一所学校都有一个天文实验室 They have a playground or school yard. 都有操场或院子 They have the sky above 头顶都有天空 They have clear days / nights 有着分明的白天和黑夜 THESE MUST BE USED! 要物尽其用!

11 We will build a model of the visible horizon from school 我们将按照在学校看到的地平线, 做一个模型

12 We begin by photographing the place of observation 首先, 我们在观测的地方拍照 local horizon 本地地平圈 Rosa M. Ros

13 Let's put the photos together on a support platform 我们将拍下的照片拼起来, 放在一个平面上 local horizon 本地地平圈

14 we must adjust the photographed horizon to align with the real horizon 我们需要将照片中的地平线对准真正的地平线 The line N - S and local meridian 南北极连线与本地子午线 Rosa M. Ros

15 To position the model we can use the compass direction, or better, we can use the projection of the pole above the horizon 我们可以根据指南针的方向定位模型另一种更好的方法是, 采用地平线上极点的投影

16 Introduce Earth s rotation 引入地球的自转轴 axis of the Earth 地轴

17 Your latitude is equal to the altitude of the pole 你的纬度与当地极点的地平高度相等

18 Indicate the apparent path of the sun on the first day of spring / autumn 引入太阳在春 / 秋季首日的运行轨迹 Use the Sunrise/Sunset photos 采用日出 / 日落的照片

19 Movement due to Earth s rotation: 地球自转造成的视运动 : Note the angle of the sun s path 记录太阳轨迹的角度 Day - several images near sunset 白天一组日落的照片

20 Movement due to Earth s rotation: 地球自转造成的视运动 : Note the angle of the star trails 记录恒星轨迹的角度 Night time exposure of stars 夜晚天体长曝光相片

21 Rotation movement in the model 模型中的自转运动

22 The inclination of the sun s apparent path and star trails depend on latitude 太阳和恒星轨迹的倾角取决于当地纬度

23 Solar paths on first day of each season (note the different durations) 四季首日的太阳轨迹 ( 记录不同的持续时间 ) Summer Solstice 夏至 Autumnal/Vernal Equinox 春分 / 秋分 Winter Solstice 冬至

24 Orbital motion leads to the seasonal positions 公转导致四季更迭 Summer 夏至 Spring / Autumn 春分 / 秋分 Winter 冬至 Angle between equator and Tropic and Cancer or Tropic of Capricorn = 23.5 º 赤道与南北回归线之间的夹角是 23.5 º

25 Earth s orbital motion leads to change the position of sunsets every day 地球公转导致了每天日落位置的变化 3 sunsets:winter-spring/autumn-summer 3 个日落点 : 冬季春 / 秋季夏季

26 Viewing the "meridian" in the model 观察模型中的子午线 Rosa M. Ros

27 around the pole: circles... 极地附近 : 绕极恒显星

28 near the equator the trajectories change from concave to convex 赤道附近, 轨迹从凹线变成凸线

29 the model is no more than an equatorial sundial! 模型不过是个赤道式日晷!

30 and from it other sundials can be made from the equatorial one 由此我们还可以制作其它日晷

31 the horizontal sundial 地平式日晷

32 and the vertically oriented sundial 垂直式日晷

33 and with the Sun (or with a flashlight) we observe the model acting like a sundial 在太阳 ( 或手电 ) 的照射下, 我们观察到这个模型像日晷一样运行

34 The three sundials in the model 模型中的三个日晷

35 Let's see how to build a very simple equatorial sundial! 我们来看看如何制作一个非常简单的赤道式日晷! Northern hemisphere 北半球 Southern Hemisphere 南半球

36 Fold the pattern on the dotted line 沿虚线折叠 Cut the stylus for your latitude. The yellow part goes above the plane 按照你的纬度剪下指针, 黄色部分用于盘面

37 How to Read Time 怎样读出时间 Solar Time + Total Adjustment = wristwatch time 太阳时 + 总调整 = 手表时间 Total Adjustment = 总调整 = Longitude Adjustment 经度调整 Summer/winter Adjustment 冬夏调整 Equation of Time Adjustment 时间等式调整 Adjust of summer / winter. 冬夏调整 Almost all countries add an hour in summer. 几乎所有国家在夏天都要加一小时 The change of summer / winter is a decision of the government of the country. 冬夏调整由该国政府决定

38 Longitude Adjustment 经度调整 The world is divided into 24 time zones from the zero meridian or Greenwich meridian. 世界从本初子午线 / 格林威治子午线起, 被划分为 24 个时区

39 Longitude Adjustment 经度调整 We must know the local longitude and "Standard" meridian longitude in your area 我们必须知道当地经度, 以及当地作为标准的经度 Use sign + to the East and sign - to the West. 以东为 +, 以西为 - Write longitudes in h, m and s (1º=4m). 经度采用小时分钟和秒来记录 (1º=4m)

40 summer/winter Adjustment 冬夏调整 Many countries add a hour in summer. 几乎所有国家在夏天都要加一小时 This change of clocks for summer / winter is a decision of the government of the country. 冬夏调整由该国政府决定

41 Equation of Time Adjustment 时间等式调整 The Earth revolves around the Sun according the law of areas, i.e. not a constant motion. We define the average time (of mechanical watches) as the average over a full year. 地球围绕太阳公转遵循各个区域的规律, 即 : 不是匀速的我们将一年的平均定义为 ( 机械时钟 ) 的平均时间 The equation of time is the difference between "Real Solar Time" and "Mean Time in Minutes of time 这个时间等式就是真太阳时和平时的差别 date Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

42 Reading Time from your sundial Example 1: Barcelona (Spain) on May 24th Adjustment Comment Result 1. Longitude Barcelona is in the same area "standard" as Greenwich. Its longitude is 2 º 10'E = 2.17 º E =- 8.7m (1 is equivalent to 4 m) -8.7 m 2. Summer Time May has daylight saving+1 h + 60 m 3. Equation of Time Total We read the table for May 24 or example at 12h of solar time (noon), our watches indicated Solar time) 12h m = 12h 47.7 m (Wristwatch time) -3.6 m m

43 在你的日晷上读取时间例 1:5 月 24 日巴塞罗那 ( 西班牙 ) 调整注解结果 1. 经度巴塞罗那与格林威治在同一标准经度其经度为 2º10'E=2.17ºE= - 8.7m (1 = 4 m) -8.7 m 2. 夏令时 5 月采用夏令时,+1 h + 60 m 3. 时间等式从表中读取 5 月 24 日 -3.6 m 合计 m 例如, 太阳时是 12:00( 正午 ), 手表的时间是 ( 太阳时 )12h m = 12h 47.7 m ( 手表时间 )

44 Read Time Example 2: Tulsa, Oklahoma (USA) November 16th Adjustment Comment Result 1. Longitude The standard meridian of Tulsa is 90 W. Its longitude is 95 º 58'W = 96 º W, then is 6 W from the standard meridian (1 is equivalent to 4 m) 2. Winter Time November 16 does not have daylight saving 3. Equation of Time Total We read the table for November 16 or example at 12h of solar time (noon), our watches indicated Solar time) 12h m = 12h 8.7 m (Wristwatch time) +24 m m m

45 时间读取例 2: 11 月 16 日塔尔萨, 俄克拉荷马州 ( 美国 ) 调整注解结果 1. 经度标准经度为 90 W, 实际经度为 95º58 W, 大约 96 W, 即距离格林威治标准经度 6 W (1 = 4 m) 2. 夏令时 11 月 16 日不是夏令时 m 3. 时间等式从表中读取 11 月 16 日 m 合计 m 例如, 太阳时是 12:00( 正午 ), 手表的时间是 ( 太阳时 ) 12h m = 12h 8.7 m( 手表时间 )

46 The model serves to orient 向东的模型

47 to observe and understand 观察和理解

48 Conclusions 总结 We understand the figures "views" from within and outside 我们理解了从内部和外部看到的图形 We reach levels of abstraction that let us read books and comment 我们达到了可以看书和写评论的抽象水平 We feel oriented to the real horizon 我们适应了真实的地平线 We see that the sunrise is not always due east and the sunset due west 我们观察到日出不总是在正东, 日落也不总是在正西

49 Thank you very much for your attention! 非常感谢! Rosa M. Ros

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