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Space Station Info :: Nine Planet Solar System :: History of Pluto :: Physical Characteristics of Pluto

Physical Characteristics of Pluto

Mass and Size of Pluto Planet

Pluto is smaller and also massive than all other planet, it is also smaller and less massive than seven moons: Ganymede, Titan, Callisto, Io, Earth's Moon, Europa and Triton. However, Pluto is more than an order of magnitude larger than any minor planet in the asteroid belt, and it was larger than any other object known in the trans-Neptunian Kuiper belt until 2003 UB313 was announced in 2005.

Pluto's mass and diameter could only be anticipated for many decades after its discovery. In 1978 the discovery of its satellite Charon enabled a determination of the mass of the Pluto-Charon system by simple relevance of Newton's formulation of Kepler's third law. Later Pluto's diameter was measured when it was occulted by Charon, and its disk can now be resolved by telescopes using adaptive optics.

Eccentric orbit of Pluto Planet

Discovery of Pluto Planet

Pluto's highly eccentric orbit makes it the eighth-most distant planet from the Sun for part of each orbit; this occurred recently from February 7, 1979 through February 11, 1999. Precise calculations specify that the previous happening only lasted fourteen years from July 11, 1735 to September 15, 1749. But, the same calculations point out that Pluto was the eighth-most distant planet between April 30, 1483 and July 23, 1503, which is precisely the same length as the 1979 to 1999 period. Latest studies imply each crossing of Pluto to inside Neptune's orbit lasts alternately for around thirteen and twenty years with minor variations.

Pluto orbits in a 3:2 orbital resonance with Neptune. When Neptune approaches Pluto from behind their gravity start to pull on each other a little, consequential in an interaction between their positions in orbit of the same sort that produces Trojan points. As the orbits are eccentric, the 3:2 periodic ratios is favoured since this means Neptune at all times passes Pluto when they're almost farthest apart. Half a Pluto orbit afterward, when Pluto is nearing its closest approach, it initially seems as if Neptune is about to catch up to Pluto. However Pluto speeds up due to the gravitational acceleration from the Sun, stays to the fore of Neptune, and pulls ahead until they meet again on the other side of Pluto's orbit.

For the reason of its small size and eccentric orbit, there has been some debate over whether it truly should be classified as a planet. There is an increasing evidence that Pluto may in fact be a member of the Kuiper belt, only one of a large number of distant icy bodies. Subclasses of such objects have been dubbed plutinos, after Pluto.


Pluto's thin atmosphere probably has the constituents of nitrogen and carbon monoxide, in symmetry with solid nitrogen and carbon monoxide ices on the surface. As Pluto moves away from its perihelion and farther from the Sun, more of its atmosphere freezes.

In 1988 Pluto was found to have an atmosphere from an occultation study. When an object with no atmosphere occults a star, the star hastily disappears; but in the case of Pluto, the star dimmed out steadily. >From the rate of dimming, the atmosphere was determined to have a pressure of 0.15 Pa.

Another occultation of a star by Pluto was observed and analyzed by teams led by Bruno Sicardy and by Jim Elliot in 2002. Astonishingly, the atmosphere was estimated to have a pressure of 0.3 Pa, although Pluto was further from the Sun than in 1988, and hence should be colder and have a less dense atmosphere. The present preeminent hypothesis is that the south pole of Pluto came out of shadow for the first time in 120 years in 1987, and extra nitrogen sublimated from a polar cap. It will take decades for the excess nitrogen to condense out of the atmosphere.

Appearance of Pluto Planet

Pluto's apparent magnitude is fainter than 14 m and therefore a telescope is necessary for inspection. To be easily seen, a telescope of around 30cm aperture is enviable. It looks star-like even in very big telescopes, for the reason that its angular diameter is only 0.15?. The Pluto has a color of light brown with a very slight tint of yellow.

Stationary, retrograde Opposition Distance to Earth
Stationary, prograde Conjunction to Sun
March 24, 2004 June 11, 2004 29.80193 13.8 August 31, 2004 December 13, 2004
March 27, 2005 June 14, 2005 29.95761 13.8 September 3, 2005 December 16, 2005
March 29, 2006 June 16, 2006 30.12128 13.9 September 5, 2006 December 18, 2006
March 31, 2007 June 19, 2007 30.29202 13.9 September 7, 2007 December 21, 2007
April 2, 2008 June 20, 2008 30.46941 13.9 September 9, 2008 December 22, 2008
April 4, 2009 June 23, 2009 30.65286 13.9 September 11, 2009 December 24, 2009
April 7, 2010 June 25, 2010 30.84244 14.0 September 14, 2010 December 27, 2010
April 9, 2011 June 28, 2011 31.03813 14.0 September 16, 2011 December 29, 2011
April 10, 2012 June 29, 2012 31.24049 14.0 September 17, 2012 December 30, 2012
April 12, 2013 July 2, 2013 31.44959 14.0 September 20, 2013 January 1, 2014
April 15, 2014 July 4, 2014 31.66530 14.1 September 22, 2014 January 3, 2015
April 17, 2015 July 6, 2015 31.88724 14.1 September 24, 2015 January 6, 2016
April 18, 2016 July 7, 2016 32.11459 14.1 September 26, 2016 January 7, 2017
April 20, 2017 July 10, 2017 32.34681 14.2 September 28, 2017 January 9, 2018
April 23, 2018 July 12, 2018 32.58277 14.2 September 30, 2018 January 11, 2019
April 25, 2019 July 14, 2019 32.58277 14.2 October 2, 2019 January 13, 2020
April 26, 2020 July 15, 2020 33.06323 14.3 October 4, 2020 January 14, 2021

See about:

vHistory of Pluto
vPluto Discovery And Naming
vPluto Physical Characteristics
vPluto's Moon
vExploration Of Pluto
vThe Pluto Debate
vPluto New Discoveries