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Our Place in the Universe, according to Monty Python


SOLAR SYSTEM DATA -- PLANETS                                             Moons             Exoplanets
Plus Dwarfs, Asteroids, NEOs, TNOs, and KBOs

A planet is a celestial body, orbiting a star or stellar remnant, that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals. By this definition, the Solar System has 8 planets and numerous smaller bodies (dwarf planets, asteroids, moons).

An extrasolar planet, or exoplanet, is a planet outside our Solar System. The first published, confirmed discovery was made in 1988
by the Canadian astronomers Bruce Campbell, G. A. H. Walker, and S. Yang. Although they were cautious about claiming a planetary detection, their radial-velocity observations suggested that a planet orbits the star Gamma Cephei.

Planets in our Solar System are divided into two types: large, low-density gas giants, and smaller, rocky terrestrials. Under IAU definitions, there are eight planets in the Solar System. In order from the Sun, they are the four terrestrials, Mercury, Venus, Earth, and Mars, then the four gas giants, Jupiter, Saturn, Uranus, and Neptune. Many of these planets are orbited by one or more moons, some of which are larger than small planets.

The Solar System also contains 5 recognized dwarf planets and numerous minor planets. Dwarf planets have sufficient gravity to form a roughly sperical shape; minor planets are smaller and may have irregular shapes. The minor planets are are Ceres, Pluto (formerly considered to be the Solar System's ninth planet), Makemake, Haumea, and Eris. Sedna, and 2012VP113 may also qualify as minor planets. No extrasolar dwarf planets have yet been detected.


               
Solar System and our neasrest neighbour Alpha Centauri, distances shown on a logaritmic scale

Asteroids are small bodies circling the Sun, mostly in the Asteroid Belt between Mars and Jupiter. However, there are asteroids with orbits as small as Mercury and larger than Neptune. A number of other asteroids have been proposed as candidates for the dwarf planet category.

Comets are small asteroid-like bodies derived from the same source as Centaurs, but their orbits reach the inner Solar System. Energy from the Sun vaporizes some of the comet's material, giving the object a distinctive tail, or coma.

Meteoroids are small fragments of asteroids or comets, usually only a few feet or less in diameter, and are invisible to telescopes due to their small size. If one enters the Earth's atmosphere, its trail through the sky becomes visible as it vaporizes due to the heat of friction. That trail of bright light is called a Meteor. If a portion of the meteoroid survives intact and reaches the ground, it is called a Meteorite. A meteor is also called a Bolide, when it is large and explodes in the air, or a Fireball when it is brighter than Venus but smaller than a bolide. Meteor showers occur when Earth passes through the orbit of a comet; the number pf meteors visible to the naked eye varies from less than a 100 per minute up to a 1000 per minute in rare cases. The apparent "source" of the meteor shower in the sky is called the Radiant.

A superbolide seared through the sky over China, Kaaakstan, and Russia in February 2012. The 60 foot, 11000 ton asteroid broke up near Chelyabinsk and was the largest meteor to hit Earth since the Tunguska event in Siberia in 1908. Coincidentally, a much larger asteroid, 2012DA14, passed within 17200 miles of Earth on the same day, but the two objects were unrelated. 2012DA14  was twice the diameter and 4 times the mass of the Chelyabinsk meteroid - pretty close call!

Trojans are small bodies that are in the same orbit as their host, either a planet or a moon. They sit at the stable Lagrangian points 60 degrees ahead and 60 degrees behind their host. Jupiter, Neptune, Mars, Earth, and some of Saturn's moons have Trojans. Earth's Trojan, 2010 TK7, was discovered by Martin Connors of Athabasca University in Alberta, Canada.

 

Other near earth objects (NEO's), besides 2010 TK7, are the asteroids 3753 Cruithne, 54509 YORP, 1998 UP1, 2002 AA29, and 2009BD which exist in resonant orbits.

Mars has four known co-orbital asteroids (5261 Eureka, 1999 UJ7, 1998 VF31, and 2007 NS2, all at the Lagrangian points), and Jupiter has more than 1000 known objects, the Trojan asteroids. 

Centaurs are asteroids, or minor planets, that have highly elliptical orbits, crossing the orbit of Neptune. These are also called Trans-Neptunian Objects (TNO's). Their orbits emanate inside the Kuiper Belt, scattered disc, and Oort Cloud, well beyond the orbit of Neptune. Their elliptical orbits can bring them as far as Jupiter before they return to their distant homes.

Moons orbit most Solar System planets except Mercury and Venus. Rings of dust and debris orbit all four gas giants. Shepard moons organize the rings into distinctive patterns, the most notable being Saturn's.

NOTES: Data from Wikipedia, photos mostly NASA credits, via Wikipedia. "Orbit" is semi-major axis (distance from center of elliptical orbit to it's maximum elongation -- equivalent to radius of a circle).

Abbreviations: AU = Astronomical Unit = 93 500 000 miles = 149 600 000 Kilometers, Yr = Years, Yg = Yoltagram = 10^21 Kilograms, g/cc =  grams per cubic centimeter, Km = Kilometer = 0.62 miles.

SUN
Primary
Member
Orbit AU
Period Yr
Inclination
Diameter Km
Mass Yg
Density g/cc

Milky Way
G2 Star
0.00
-----
-----
1390000
1.99*10^9
1.41
MERCURY
Primary
Member
Orbit AU
Period Yr
Inclination
Diameter Km
Mass Yg
Density g/cc

Sun
Inner Planets
0.39
0.24
7.00
4880
330
5.43
VENUS
Primary
Member
Orbit AU
Period Yr
Inclination
Diameter Km
Mass Yg
Density g/cc

Sun
Inner Planets
0.72
0.62 retrograde
3.39
12104
4870
5.24
EARTH
Primary
Member
Orbit AU
Period Yr
Inclination
Diameter Km
Mass Yg
Density g/cc

Sun
Inner Planets
1.00
1.00
0.00
12756
5970
5.52
 
MARS
Primary
Member
Orbit AU
Period Yr
Inclination
Diameter Km
Mass Yg
Density g/cc

Sun
Inner Planets
1.52
1.88
1.85
6794
642
3.93
CERES
Primary
Member

Orbit AU
Period Yr
Inclination
Diameter Km
Mass Yg
Density g/cc

Sun
Asteroid Belt
   Dwarf Planet
2.98
4.60
10.6
950
0.94
n/a
LARGE  ASTEROIDS

Name:      Vesta   Pallas    Hygiea    Davida 
                              
Mass Yg:   0.27       0.21        0.09          0.03

       Interamnia  Eunomia   Juno      Eros
                                        
              0.03          0.01      0.01       0.007                             
JUPITER
Primary
Member
Orbit AU
Period Yr
Inclination
Diameter
Mass Yg
Density g/cc
 

Sun
Outer Planets
5.20
11.86
1.31
142984
1900000
1.33
 
SATURN
Primary
Member
Orbit AU
Period Yr
Inclination
Diameter Km
Mass Yg
Density g/cc
 

Sun
Outer Planets
9.55
29.46
2.49
120536
568000
0.69
 
URANUS
Primary
Member
Orbit AU
Period Yr
Inclination
Diameter Km
Mass Yg
Density g/cc

Sun
Outer Planets
19.19
84.01
0.77
51118
86800
1.32
  CENTAURS
                Orb  Per  Incl  Dia
                 AU   Yr           Km
Chariklo 15.9  63.2  13.4  258
Asbolus  18.1  76.9  17.6    76
Nessus    24.6 122.4 15.6    60
Pholus    20.4  91.8  24.6  185
Chiron    13.7  50.5    6.9  233

Many others

 

 

NEPTUNE
Primary
Member
Orbit AU
Period Yr
Inclination
Diameter Km
Mass Yg
Density g/cc

Sun
Outer Planets
30.11
164.79
1.77
49532
102000
1.64

    Pluto   -Charon

     Orcus        Ixion


Haumea

           
              Makemake


   Dysnomia    Eris
 

KUIPER BELT
 

Dwarf Planets and Dwarf Candidates
          ===>

 


 

  
                      Orbit    Diameter   Mass
                         AU         Km           Yg
Kuiper Belt    35-100
  Orcus            39.12        946         0.75
  Pluto             39.53      2306**      12.7 ===>
  Ixion             39.65        980         0.58
  Huya             39.76        480         0.16
  Salacia         39.19        850         0.46
  Varuna         42.90         875        0.59
  2002TX300    43.11         800        0.37
  Quaoar         43.40       1110         1.4
  Haumea       43.34       1100**       4.2
  Quaoar        43.58        1200**       2.6
  Makemake  45.79        1500           ?

  2002AW197  47.30         890         0.52
  2002TC302   55.02       1150        0.078
  Eris              67.67       2400**          16       
  1996TL66     82.90         632          0.26
Oort Cloud  100-5  
 2012VP113 265.0           450             ??  
 Sedna        524.0         1000            6.1 ===>
       Sedna has largest semi-major axis
       but 2012VP has largest perihelion

** Dwarf Planets as of 2012, more may be added


http://en.wikipedia.org/wiki/List_of_Solar_System_objects