INTRODUCTION
Pluto was discovered by Clyde
Tombaugh in 1930 and was originally considered to be the ninth planet from
the Sun. After 1992, its status as a planet was questioned following
the discovery of several objects of similar size in the Kuiper belt. In 2005, Eris,
a dwarf planet in the scattered disc which is 27% more massive than
Pluto, was discovered. This led the International Astronomical Union (IAU)
to define the term "planet" formally in 2006, during their
26th General Assembly. That definition excluded Pluto and reclassified it as a
dwarf planet.
Region where Ice has been detected
Pluto
is the largest and second-most-massive known dwarf planet in the Solar
System, and the ninth-largest and tenth-most-massive known object
directly orbiting the Sun. It is the largest known trans-Neptunian
object by volume but is less massive than Eris. Like other Kuiper belt
objects, Pluto is primarily made of ice
and rock and is relatively small—about one-sixth the mass of the Moon and
one-third its volume. It has a moderately eccentric and inclined orbit during which it ranges from 30 to 49 astronomical units or AU
(4.4–7.4 billion km) from the Sun. This means that Pluto periodically
comes closer to the Sun than Neptune, but a stable orbital resonance with
Neptune prevents them from colliding. Light from the Sun takes about
5.5 hours to reach Pluto at its average distance (39.5 AU).
Pluto has five known moons: Charon (the
largest, with a diameter just over half that of Pluto), Styx, Nix, Kerberos,
and Hydra. Pluto and Charon are
sometimes considered a binary system because the barycenter of
their orbits does not lie within either body.
ORBIT OF PLUTO WITH REALTION TO NEPTUNE
ORBIT OF PLUTO WITH REALTION TO NEPTUNE
Pluto was discovered in 1930 near the star δ Geminorum, and merely coincidentally crossing the ecliptic at this time of discovery. Pluto moves about 7 degrees east per decade with small apparent retrograde motion as seen from Earth. Pluto was closer to the Sun than Neptune between February 7, 1979, and February 11, 1999.In the long term, Pluto's orbit is chaotic.
The plains on Pluto's surface are composed of more than 98 percent nitrogen ice, with traces of methane and carbon monoxide. Nitrogen and carbon monoxide are most abundant on the anti-Charon face of Pluto (around 180° longitude, where Tombaugh Regio's western lobe, Sputnik Planitia, is located), whereas methane is most abundant near 300° east. The mountains are made of water ice. Pluto's surface is quite varied, with large differences in both brightness and color. Pluto is one of the most contrastive bodies in the Solar System, with as much contrast as Saturn's moon Iapetus.
It has no craters that were visible to New Horizons, indicating that its surface is less than 10 million years old. Latest studies have shown that the surface has an age of 180000+90000
−40000 years.
−40000 years.
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