The Dwarf Planet

The Dwarf Planet

  • Submitted By: myflock
  • Date Submitted: 03/02/2009 8:15 AM
  • Category: Science
  • Words: 691
  • Page: 3
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This article is about the dwarf planet. For other uses, see Pluto (disambiguation).
Semi-protected
Pluto Astronomical symbol of Pluto
Map of Pluto based on Charon eclipses, approximately true colour and giving the highest resolution possible with current technology
Discovery
Discovered by Clyde W. Tombaugh
Discovery date February 18, 1930
Designations
MPC designation 134340 Pluto
Minor planet
category dwarf planet,
TNO,
plutoid,
KBO,
plutino
Adjective Plutonian
Orbital characteristics
Epoch J2000
Aphelion 7 375 927 931 km
49.305 032 87 AU
Perihelion 4 436 824 613 km
29.658 340 67 AU
Semi-major axis 5 906 376 272 km
39.481 686 77 AU
Eccentricity 0.248 807 66
Orbital period 90 613.305 days
248.09 years
Synodic period 366.73 days
Average orbital speed 4.666 km/s
Inclination 17.141 75°
11.88° to Sun's equator
Longitude of ascending node 110.303 47°
Argument of perihelion 113.763 29°
Satellites 3
Physical characteristics
Mean radius 1,195 km[1]
0.19 Earths
Surface area 1.795×107 km²
0.033 Earths
Volume 7.15×109 km³
0.006 6 Earths
Mass (1.305 ± 0.007)×1022 kg[2]
0.002 1 Earths
0.178 moon
Mean density 2.03 ± 0.06 g/cm³[2]
Equatorial surface gravity 0.58 m/s²
0.059 g
Escape velocity 1.2 km/s
Sidereal rotation
period '6.387 230 day
6 d 9 h 17 m 36 s
Equatorial rotation velocity 47.18 km/h
Axial tilt 119.591 ± 0.014° (to orbit)[2][3]
North pole right ascension 133.046 ± 0.014°[2]
North pole declination -6.145 ± 0.014°[2]
Albedo 0.49–0.66 (varies by 35%)[4][1]
Surface temp.
Kelvin
min mean max
33 K 44 K 55 K
Apparent magnitude up to 13.65 (mean is 15.1)[1]
Absolute magnitude (H) '0.7[5]
Angular diameter 0.065" to 0.115"[1][6]
Atmosphere
Surface pressure 0.30 Pa (summer maximum)
Composition nitrogen, methane

Pluto (pronounced en-us-Pluto.ogg /ˈpluːtoʊ/ (help·info), from Latin: Plūto), formal designation (134340) Pluto, is the second-largest known dwarf planet in...

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