Monday, January 16, 2006


Mass (kg): 3.3 x 10 23
Diameter (km): 4879.4
Mean density (kg/m 3 ): 5420
Escape velocity (m/s): 4300
Average distance from Sun: 0.387 AU (57,909,175 km)
Rotation period (length of day in Earth days): 58.65
Revolution period (length of year in Earth days): 87.97
Obliquity (tilt of axis degrees): 0
Orbit inclination (degrees): 7
Orbit eccentricity (deviation from circular): 0.206
Mean surface temperature (K): 452 (179 o C)
Maximum surface temperature (K): 700 (427 o C)
Minimum surface temperature (K): 100 (-173 o C)
Satellites: None
Visual geometric albedo: (reflectivity): 0.12
Largest known surface feature: Caloris Basin (1350 km diameter)
Atmospheric components: trace amounts of hydrogen (H) and helium (He)
Surface materials: basaltic and anorthositic rocks and regolith


Mass (kg): 4.87 x 1024
Diameter (km): 12104
Mean density (kg/m3): 5250
Escape velocity (m/s): 10400
Average distance from Sun: 0.723 AU (108,208,930 km)
Rotation period (length of day in Earth days): 243.02 (retrograde) Revolution period (length of year in Earth days): 224.7
Obliquity (tilt of axis degrees): 178
Orbit inclination (degrees): 3.39
Orbit eccentricity (deviation from circular): 0.007
Mean surface temperature (K): 726 (453 oC)
Satellites: None
Visual geometric albedo: (reflectivity): 0.59
Highest point on surface: Maxwell Montes (17 km above mean planetary radius)
Atmospheric components: 96% carbon dioxide (CO2), 3% nitrogen (N), 0.1% water vapor (H2O(g))
Surface materials: basaltic rock and altered materials


Mass (kg): 5.98 x 1024
Diameter (km): 12756
Mean density (kg/m3): 5520
Escape velocity (m/s): 11200
Average distance from Sun: 1 AU (149,597,890 km)
Rotation period (length of day in Earth days): 1 (23.93 hours) Revolution period (length of year in Earth days): 365.26
Obliquity (tilt of axis degrees): 23.4
Orbit inclination (degrees): 0
Orbit eccentricity (deviation from circular): 0.017
Mean surface temperature (K): 281 (8 oC)
Maximum surface temperature (K): 328 (55 oC)
Minimum surface temperature (K): 203 (-70 oC)
Satellites: One (Moon)
Visual geometric albedo: (reflectivity): 0.39
Highest point on surface: Mount Everest (over 8 km above sea-level)
Atmospheric components: 78% nitrogen (N), 21% oxygen (O2), 1% argon (Ar)
Surface materials: basaltic and granitic rock and altered materials


Diameter (km): 3476
Average distance from Earth: 384,600 km
Maximum surface temperature (K): 378 (105 oC)
Minimum surface temperature (K): 118 (-155 oC)
Atmospheric components: There aren’t any


Mass (kg): 6.42 x 1023
Diameter (km): 6787
Mean density (kg/m3): 3940
Escape velocity (m/s): 5000
Average distance from Sun: 1.524 AU (227,936,640 km)
Rotation period (length of day in Earth days): 24.6
Revolution period (length of year in Earth days): 686.98
Obliquity (tilt of axis degrees): 25
Orbit inclination (degrees): 1.85
Orbit eccentricity (deviation from circular): 0.093
Maximum surface temperature (K): 310 (37oC)
Minimum surface temperature (K): 150 (-123 oC)
Satellites: Two Visual geometric albedo: (reflectivity) 0.15
Highest point on surface: Olympus Mons (about 24 km above surrounding lava plains)
Atmospheric components: 95% carbon dioxide (CO2), 3% nitrogen (N), 1.6% argon (Ar)
Surface materials: basaltic rock and altered materials


Mass (kg): 1.90 x 1027
Diameter(km): 142,800
Mean density(kg/m3): 1314
Escape velocity(m/s): 59500
Average distance from Sun: 5.203 AU (778,412,020 km)
Rotation period(length of day in Earth days): 0.41 (9.8 Earth hours)
Revolution period (length of year in Earth years): 11.86
Obliquity(tilt of axis degrees): 3.08
Orbit inclination (degrees): 1.3
Orbit eccentricity (deviation from circular): 0.048
Mean surface temperature (K): 120 (cloud tops) (-153 oC)
Satellites: 62
Visual geometric albedo
(reflectivity): 0.44
Atmospheric components: 90% hydrogen (H), 10% helium (He), .07% methane (CH4)
Rings: Faint ring. Infrared spectra imply dark rock fragments.


Mass (kg): 5.69 x 1026
Diameter (km): 120660
Mean density (kg/m3): 690
Escape velocity (m/s): 35600
Average distance from Sun: 9.537 AU (1,426,725,400 km)
Rotation period (length of day in Earth days): 0.44 (10.2 Earth hours) Revolution period (length of year in Earth years): 29.46
Obliquity (tilt of axis degrees): 26.7
Orbit inclination (degrees:) 2.49
Orbit eccentricity (deviation from circular): 0.056
Mean temperature (K): 88 K (1 bar level) (-185 oC)
Satellites: 31

Visual geometric albedo: (reflectivity) 0.46
Atmospheric components: 97% hydrogen (H), 3% helium (He), .05% methane (CH4)
Rings: Rings are 270,000 km in diameter, but only a few hundred meters thick. Particles are centimeters to decameters in size and are ice (some may be covered with ice); there are traces of silicate and carbon minerals. There are four main ring groups and three more faint, narrow ring groups separated by gaps called divisions.


Mass (kg): 8.68 x 1025
Diameter (km): 51118
Mean density (kg/m3): 1290
Escape velocity (m/s): 21300
Average distance from Sun: 19.19 AU (2,870,972,200 km)
Rotation period (length of day in Earth days): 0.72 (17.9 Earth hours)(retrograde)
Revolution period (length of year in Earth days): 30,685 (84 Earth years)
Obliquity (tilt of axis degrees): 97.9
Orbit inclination (degrees): 0.77
Orbit eccentricity (deviation from circular): 0.047
Mean temperature (K): 59 (-214 oC)
Satellites: 27
Visual geometric albedo: (reflectivity) 0.56
Atmospheric components: 83% hydrogen (H), 15% helium (He), 2% methane (at depth) (CH4)
Rings: Uranus has a system of narrow, faint rings. Rings particles are dark, and could consist of rocky or carbonaceous material.


Mass (kg): 1.02 x 1026
Diameter (km): 49528
Mean density (kg/m3): 1640
Escape velocity (m/s): 23300
Average distance from Sun: 30.07 AU (4,498,252,900 km)
Rotation period (length of day in Earth days): 0.67 (19.1 hours)
Revolution period (length of year in Earth days): 60,190 (164.8 Earth years) Obliquity (tilt of axis degrees): 29.6
Orbit inclination (degrees): 1.77
Orbit eccentricity (deviation from circular): 0.009
Mean temperature (K): 48 (-225 oC)
Satellites: 13
Visual geometric albedo: (reflectivity) 0.51
Atmospheric components: 74% hydrogen (H), 25% helium (He), 1% methane (CH4) (at depth)
Rings: Rings are narrow, and contain concentrations of particles called ring arcs.


Mass (kg): 1.29 x 1022
Diameter (km): 2300
Mean density (kg/m3): 2030
Escape velocity (m/s): 1100
Average distance from Sun: 39.48 AU (5,906,376,200 km)
Rotation period (length of day in Earth days): 6.39 (retrograde)
Revolution period (length of year in Earth years): 247.92
Obliquity (tilt of axis degrees): 122.5
Orbit inclination (degrees): 17.15
Orbit eccentricity (deviation from circular): 0.248
Mean temperature (K): 37 (-236 oC)
Satellites: 1
Visual geometric albedo: (reflectivity) about 0.5
Atmospheric components: perhaps methane (CH4) and nitrogen (N)
Surface materials: perhaps methane ice


Definition: Minor planets, small rocky bodies.
Composition: Leftover material from our solar system.
Largest asteroid: 1 Ceres
Total discovered to date: Over 250,000 designations have been assigned by the Minor Planet Center; over 100,000 have been observed more than once.
Total numbered asteroids to date: Over 30,000.
Near-Earth asteroids: Around 1.0 AU from earth, with perihelia less than or equal to 1.3 AU.

Aten group <><><><><> Innermost, semi-major axis less than 1.0 AU, perihelion greater than 0.983 AU.
Apollo group <><><><><> Semi-major axis greater than 1.0 AU, perihelion less than 1.017 AU.
Amor group <><><><><> Semi-major axis greater than 1.0 AU, perihelion between 1.017 and 1.3 AU.

Main Belt Asteroids: Located between orbits of Mars and Jupiter (1.8 to 4.0 AU) in the "asteroid belt".
Trojan Asteroids: Two groups of asteroids located along the orbital path of Jupiter, 60 degrees ahead and behind the planet.
Centaurs: Asteroids in the outer solar system having orbits between Mars and beyond Neptune.
Type Classification: Based on albedo (reflectivity), and color or spectra. Most common are C, S, and M.
C-type: Very dark (albedo=0.03), flat spectra, grayish in color.
S-type: Moderately bright (albedo=0.10-0.22), spectra with moderate to strong absorption bands, greenish to reddish in color.
M-type: Moderately bright (albedo=0.10-0.18), spectra with few absorption bands, reddish in color.


Definition: Icy planetesimals formed in the outer solar system.
Composition: Mainly ice and dust
Orbits: Highly elliptical, taking them very close to the Sun and back out into deep space, often far beyond the orbit of Pluto.
Orbit duration: Less than 200 years to more than several millions of years.

*Short-period <><><><><> *Orbits range from a few years (Encke, Chiron) to about 200 years. Referred to as "periodic".
*Long-period <><><><><> *Gravitationally bound, with orbits over 200 years.
*Single-apparition <><><><><> *Parabolic and hyperbolic orbits (not bound).

Periodic comets: Those with short orbit durations
Nucleus: Main body of the comet, composed of dust particles trapped in a mixture of ices of water, carbon monoxide, carbon dioxide, methane, and ammonia. Typically only a few kilometers in diameter.
: A halo of evaporated gas and dust which forms when the comet approaches the inner solar system. The coma grows larger as the comet gets closer to the sun.


Definition: Meteorites are pieces of solar system debris that have fallen to Earth from space. Prior to reaching Earth's surface, a meteorite is called a "meteor" or "meteoroid.")

Composition: Rock or metal

Size: Most meteorites are tiny, smaller than grains of sand, and vaporize as they pass through the earth's atmosphere. Larger meteorites may be as great as a few miles wide, such as one 65 million years ago that may have wiped out the dinosaurs. The largest intact meteorite found in the USA is the Williamette Meteorite, at 15 and a half tons.

Wednesday, January 11, 2006

Trans-Neptunian Objects

Definition: Trans-Neptunian objects (TNOs) are any objects in the solar system that have an orbit beyond Neptune. Pluto is a trans-Neptunian object; another of the named Trans-Neptunian Objects is Varuna.

Total known: There are estimated to be perhaps 70,000 TNOs, each at least 100 km across, between 30 and 50 astronomical units from the Sun.
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