The planets and the Sun


last updated 5 March 2012

(See notes following tables.)

planet
or object
type average
distance
from Sun
(Earth=1)
orbital period
(d)ays or (y)ears
diameter
(Earth=1)
average surface
temperature
Celsius
structure atmosphere surface known moons
(Sun) star -- -- 109 5600°
(sunspots 3500°)
H and He plasma, fusion reactions in core, corona and solar wind above surface 13 planets and dwarf planets, 573,000 asteroids, 1,600 TNOs, 4,300 comets
Mercury terrestrial 0.4 90 d 0.38 180°
(430° to -170°)
rock, metal core none craters none
Venus terrestrial 0.7 220 d 0.95 460° rock, metal core thick, CO2, some N2 plains, volcanic features, covered by clouds none
Earth terrestrial 1.0 1.0 y 1.0 10° (40° to -20°) rock, metal core N2, O2 water oceans, varied geologic activity on land, life 1 large
Mars terrestrial 1.5 1.9 y 0.53 -45° (-100° to 0°) rock, metal core thin, CO2, some N2 craters, plains, volcanoes, canyons, polar caps 2 small
Jupiter jovian 5 12 y 12 -120°
(cloudtops)
mostly liquid metallic hydrogen, atmosphere, rock core thick, H2, He cloudtops: cloud bands, circular storms 67 (4 large); faint rings
Saturn jovian 10 30 y 9 -155°
(cloudtops)
liquid hydrogen, atmosphere, rock/ice core thick, H2, He cloudtops: cloud bands, haze 62 (1 large, 6 medium); rings
Uranus jovian 19 80 y 4 -200°
(cloudtops)
atmosphere, ice, rock core thick, H2, He, CH4 cloudtops: clouds, haze 27 (5 medium); narrow rings
Neptune jovian 30 160 y 4 -205°
(cloudtops)
atmosphere, ice, rock core thick, H2, He, CH4 cloudtops: cloud bands, storms 13 (1 large); narrow rings

Note: In 2006 the International Astronomical Union reclassified Pluto as a dwarf planet instead of a planet. This decision has not been recognized by all astronomers.


The dwarf planets--and some possible dwarf planets

object type average
distance
from Sun
(Earth=1)
orbital period
(d)ays or (y)ears
diameter
(Earth=1)
average surface
temperature
Celsius
structure atmosphere surface known moons
Ceres asteroid 2.8 4.6 y 0.07 -110° rock and ice? none rock, ice none
Pluto TNO 39
(range 30-49)
250 y 0.18 -230° various ices, rock core thin, N2, CH4, CO various ices 3 (1 medium, 2 small)
Haumea TNO 43
(range 34-51)
280 y 0.10 -240°? various ices, rock core? ? various ices? 2 small
Makemake TNO 45
(range 38-53)
310 y 0.11 -245°? various ices, rock core? ? various ices? none
(225088) 2007 OR10* TNO 67
(range 34-101)
550 y 0.11 -230° to -245°? various ices, rock core? ? various ices? none
Eris TNO 68
(range 39-98)
560 y 0.18 -245° to -255°? various ices, rock core? ? various ices? 1 small
Sedna* TNO 540
(range 76-1,000)
12,400 y 0.13 -240° to -265°? various ices, rock core? none? various ices? none

Note: Only Pluto, Eris, Haumea, Makemake, and Ceres are officially designated dwarf planets. Of many candidate dwarf planets, the largest are listed here and designated with *.


The planet-sized moons

moon primary
planet
average
distance
from center
of planet
orbital period
(d)ays
diameter
(Earth=1)
average surface
temperature
Celsius
structure atmosphere surface
Moon Earth 380,000 km 27 d 0.27 100° to -170° rock/metal none craters, lava plains
Io Jupiter 400,000 km 2 d 0.28 0° to -190° rock, metal core none volcanoes, volcanic runoff
Europa Jupiter 700,000 km 4 d 0.25 -150° to -190° rock/metal, ice crust over a water ocean none ice, frozen fractures
Ganymede Jupiter 1,100,000 km 7 d 0.41 -130° to -190° ice, rock core none dirty ice plains, craters, ridges
Callisto Jupiter 1,900,000 km 17 d 0.38 -130° to -190° rock, ice none craters, ice and dirt
Titan Saturn 1,200,000 km 16 d 0.40 -140° to -190° rock, ices N2, CH4 various ices, methane sludge?, covered by haze
Triton Neptune 350,000 km 6 d 0.18 -230° rock, ices thin, N2, CH4 plains of various ices, craters, geysers

These tables are intentionally simplified to give a quick overview of planetary characteristics--you should not prefer this data over more precise or up-to-date data from other sources. More data, and more precise data, are available from many sources such as the National Space Science Data Center at http://nssdc.gsfc.nasa.gov/planetary/. Date of this data: January 2012.

The jovian planets do not have accessible surfaces, so information at their cloudtops is substituted for "surface" data. The Earth-Sun average distance is 150,000,000 kilometers (km); Earth's diameter is 12,700 km. "TNO" is trans-Neptunian object, which refers to large icy asteroid-like objects beyond Neptune. "Ice" refers to water ice, "ices" may include other ices: nitrogen, methane, ammonia. For size of moons, "large" refers to those over 2,000 km diameter and "medium" to those between 350 and 2,000 km in diameter. In addition to the 170 known moons of planets and dwarf planets, there are 89 known moons of asteroids and 48 known moons of trans-Neptunian objects.

The chemical symbols used are for methane (CH4), carbon monoxide (CO), carbon dioxide (CO2), hydrogen (H), molecular hydrogen (H2), helium (He), nitrogen (N2), oxygen (O2).


Last modified 5 March 2012.
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