固體地球物理學概論第二章1

1、第二章 地球的起源 The Formation of the Earth,地球起源的問題，不僅是地球科學，而且是自然科學中的一個基本理論問題。因為地球是太陽系的成員之一，所以地球的起源和太陽系的起源基本上是一個問題。,§ 2.1 太陽系與地球The Solar System and the Earth 地球只是太陽系中的普通一員。而太陽只是銀河系中億萬顆恒星中的一名小卒。2.1.1 太陽系的成員,太陽系有

2、九大行星。 水星（Mercury)、金星（Venus）、 地球（Earth）、火星（Mars）、 木星（Jupiter）、土星（Saturn）、 天王星(Uranus)、海王星(Neptune)、 冥王星( Pluto ）,九大行星位置排列示意圖太陽、水星、金星、地球、火星、木星、土星、天王星、海王星、冥王星。太陽系約有30000多個小行星，最大的小行星叫谷神（Ceres）,直徑約730km。,除此之外，現(xiàn)已發(fā)現(xiàn)在火星

3、和木星軌道間至少存在30000顆小行星，其中最大的一叫谷神星（Ceres），是1801年發(fā)現(xiàn)的，直徑約730km。九大行星中。大多數(shù)都有自己的衛(wèi)星，最多的是木星，已發(fā)現(xiàn)有12個衛(wèi)星。衛(wèi)星也是太陽系的組成部分。慧星也是太陽系的成員。到目前為止，已觀測到的慧星有1500多顆。,當慧星從太陽身邊路過時，壯麗的慧尾，耀眼奪目，給人以難忘的印象。慧星的出現(xiàn)，并不表明災難的降臨，而是一種天體的自然現(xiàn)象。它非但不是不吉祥的預兆，而且為人類提供了研

4、究太陽系的起源和演化的難得的良機。1 太陽（The Sun）太陽是太陽系的中心，是太陽系中質(zhì)量和體積最大的天體。,,This image was acquired from NASA's Skylab space station on December 19, 1973. 質(zhì)量 Mass (kg): 1.989e+30 (330,000 Earths) 赤道半徑Equatorial radius (km) 6

5、95,000 平均密度Mean density (gm/cm3) 1.410 轉(zhuǎn)動周期 Rotational period (days) 25.36 平均表面溫度 Mean surface temperature 6,000°C 注：把地球質(zhì)量記為1.10123單位。,主要化學成份 Principal chemistry 氫 Hydrogen 92.1% 氦

6、 Helium 7.8% 氧 Oxygen 0.061% 碳 Carbon 0.030%,2 水星（Mercury),質(zhì)量 Mass (kg): 0.0556 Earths) 平均半徑 Mean radius (km) 2,434 平均密度Mean density (gm/cm3) 6.03 轉(zhuǎn)動周期 Rotational period

7、 (days) 59.7平均距太陽距離 Mean distance from the Sun (Earth = 1) ：0.3871,See the press release of May 28, 1998 (http://oposite.stsci.edu/pubinfo/pr/1998/19/pr.html) for more information. However, the spot in the lower lef

8、t hand region of the above Hubble image is very likely a large (about 2-3 times the size of Jupiter) planet ejected from a set of young (< 10 my old) stars.,3、金星（Venus）,質(zhì)量Mass (kg) 4.869e+24 (81% earth) 半徑Equatoria

9、l radius (km) 6,051.8 半徑Equatorial radius (Earth = 1) .94886 平均密度Mean density (gm/cm^3) 5.25 平均距太陽距離Mean distance from the Sun (Earth = 1) 0.7233,轉(zhuǎn)動周期 Rotational period (days) -243.0187 (Backwards!!)

10、Orbital period (days) 224.701 平均表面溫度 Mean surface temperature 482°C Atmospheric pressure (bars) 92 大氣成份 Atmospheric composition ： 二氧化碳 Carbon dioxide 96% 氮 Nitrogen >3%,其它： 二氧化硫Sulfur

11、 dioxide,水汽water vapor, 一氧化碳carbon monoxide, 氬argon, 氦 helium, 氖neon, 氯化氫hydrogen chloride, and 氟化氫hydrogen fluoride.,4、地球（The Earth）,Mass (kg) 1.0000e+00 赤道半徑Equatorial radius (km) 6,378.14 Mean density (gm/c

12、m^3) 5.515 Mean distance from the Sun (km) 149,600,000 Rotational period (days) 0.99727 Rotational period (hours) 23.9345,Image of earth taken from the Galileo probe enroute to Jupiter in 1990 Produced by USGS Flagst

13、aff,,軌道周期 Orbital period (days) 365.256 Mean surface temperature 15°C Atmospheric pressure (bars) 1.013 大氣成份 Atmospheric composition： 氮 Nitrogen 77% 氧 Oxygen 21%

14、 其它 Other 2%,其它觀測資料 Other Observations: Has Plate Tectonics 板塊構(gòu)造Has Volcanism 火山作用Mostly Covered with Water 大部分由水覆蓋Strong Magnetic Field 強磁場,月亮（Moon）,Mass (kg) 7.349e+22 (1.2% earth) 赤道半徑Eq

15、uatorial radius (km) 1,737.4 (27% earth) Mean density (gm/cm^3) 3.34 (Light!) Mean distance from Earth (km) 384,400 Rotational period (days) 27.32166 Orbital period (days)27.32166,5、火星（Mars）,Mass (kg) 6.421e+23 (~

16、11% of earth) Equatorial radius (km) 3,397.2 (~50% of earth) Mean density (gm/cm^3) 3.94 Mean distance from the Sun (km) 227,940,000 Rotational period (hours) 24.6229 Rotational period (days) 1.025957,,Orbital peri

17、od (days) 686.98Mean surface temperature -63°C Maximum surface temperature 20°C Atmospheric pressure (bars) 0.007 (0.0068 to 0.009) 大 氣成份 Atmospheric composition ：二氧化碳 Carbon Dioxide (C02) 95.3

18、2% 氮 Nitrogen (N2) 2% 氬 Argon (Ar) 1.6% 氧 Oxygen (O2) 0.13% 水 Water 0.03%,Other Observations Ha

19、s seasons 季節(jié)- atmosphere but weakVolcanism 火山Weather - water clouds, wind storms, evidence for floods, polar ice caps (CO2 and H20) Appears to have a crust, mantle, and core Extreme topographic variations (-4 to 27 k

20、m) Two small moons,Martian South Pole about 400 km wide (smallest extent),6、木星（Jupiter）,Mass (kg) 1.900e+27 (320% earth) Equatorial radius (km) 71,492 (11.2 earths) Mean density (gm/cm^3) 1.33 Mean distance from t

21、he Sun (km) 778,330,000 (5.3 times earth) Rotational period (days) 0.41354 Orbital period (days) 4332.71,Juipiter as seen by the Hubble Space Telescope in 1995,Mean cloud temperature -121°C Atmospheric pressur

22、e (bars) 0.7 Atmospheric composition 氫 Hydrogen 90% 氦 Helium 10%,Other Observations Extremely strong magnetic field, maybe produced by a metallic hydrogen dynamo Has a

23、ring complex of small dust particles High winds (~400 km/hour) observed by probe 16 known moons (4 of which you can see with binoculars),7、土星（Saturn）,Mass (kg) 5.688e+26 (95 earths) Equatorial radius (km) 60,268 (9

24、.5 earths) Mean density (gm/cm^3) 0.69 (Low!) Mean distance from the Sun (km) 1,429,400,000 (9.5 earth) Rotational period (hours) 10.233 (fast! planet visibly flattened) Orbital period (years) 29.458,Mean cloud t

25、emperature -125°C Atmospheric pressure (bars) 1.4 Atmospheric composition 氫 Hydrogen 97% 氦 Helium 3% 發(fā)現(xiàn)甲烷 Methane detected Other Observations Rings of unknown

26、 composition (but some kind of ice),18 confirmed plus 4 maybe moons Also gives off more energy than receives ~12000K at center due to Kelvin-Helmholtz mechanism but may also need another source to make it this hot (rain

27、ing our of He??) Probably has a metallic hydrogen core like Jupiter. Titan - largest moon in the solar system.,8、天王星（Uranus）,Mass (kg) 8.686e+25 (14 earths) Equatorial radius (km) 25,559 (4 earths) Mean density (g

28、m/cm^3) 1.29 Mean distance from the Sun (km) 2,870,990,000 (20 earths) Rotational period (hours) -17.9 Orbital period (years) 84.01,Tilt of axis (degrees) 97.86 Mean temperature -193°C Atmospheric pressure (b

29、ars) 1.2 Atmospheric composition : 氫 Hydrogen 83% 氦 Helium 15% 甲烷 Methane 2%,but: Uranus is composed primarily of rock and various ices, with only about 15% hydrogen and a li

30、ttle helium (in contrast to Jupiter and Saturn which are mostly hydrogen). Other observations Very few features visible on planet, blue from absorption of red by the methane.,Also has rings (found before Jupiter's

31、) Planet's axis of rotation is nearly 90 degrees from the plane of its rotation about the sun!! It is rolling like a ball. Has magnetic field (but origin unknown as metallic hydrogen unlikely - not enough pressure)

32、. The axis of this is tilted at 60 degrees from its axis of rotation. Appears to be cold inside, is not giving off extensive radiation.,9、海王星（Neptune）,Mass (kg) 1.024e+26 (17 earths) Equatorial radius (km) 24,746 (3.

33、9 earths) Mean density (gm/cm^3) 1.64 Mean distance from the Sun (km) 4,504,300,000 (30 earths) Rotational period (hours) 16.11 Orbital period (years) 164.79,Mean cloud temperature -193 to -153°C Atmospheric p

34、ressure (bars) 1-3 Atmospheric composition 氫 Hydrogen 85% 氦 Helium 13% 甲烷 Methane 2% Other observations The first two thirds of Neptune is composed of a mixture

35、of molten rock, water, liquid ammonia and methane.,comprised of hydrogen, helium, water and methane. Methane gives Neptune its blue cloud color. Cirrus type clouds seen (see figure) Winds of 2000 km/hour observed Fou

36、r sets of weak rings Magnetic field tilted at 47 degrees from rotation axis and offset 0.55 the planets diameter from its center!,10、冥王星（Pluto）,Mass (kg) 1.27e+22 (0.002 earths) Equatorial radius (km) 1,137 (17% e

37、arth) Mean density (gm/cm^3) 2.05 Mean distance from the Sun (km) 5,913,520,000 (40 earths) Rotational period (days) -6.3872 Orbital period (years) 248.54,Tilt of axis (degrees)122.52 Orbital inclination (degre

38、es) 17.148 Surface temperature ~-230 degrees Atmospheric composition 甲烷 Methane 0.3% 氮 Nitrogen Pluto's composition is unknown, but its density (about 2 gm/cm3) indicates that it i

39、s probably a mixture of 70% rock and 30% water ice much like Triton.,The bright areas of the surface seem to be covered with ices of nitrogen with smaller amounts of (solid) methane and carbon monoxide. The composition o

40、f the darker areas of Pluto's surface is unknown but may be due to primordial organic material or photochemical reactions driven by cosmic rays. Other observations Rotational plane highly tilted (122 degrees) with