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On the International Astronomical Union (IAU) on August 24, 2006, limiting the number to eight and defines " planet “ You will need a WHOLE sheet of paper

PLANET: –a celestial body that, within the Solar System, is in orbit (path of one object around a point or another point) around the Sun;

PLANET: –a celestial body that, within the Solar System, is in orbit (path of one object around a point or another point) around the Sun; has sufficient mass for its self-gravity to overcome rigid body forces (is an idealization of a solid body of finite size in which deformation is neglected. In other words, the distance between any two given points of a rigid body remains constant in time regardless of external forces exerted on it.) so that it assumes a hydrostatic equilibrium shape; and (nearly round)

PLANET: –a celestial body that, within the Solar System, is in orbit (path of one object around a point or another point) around the Sun; has sufficient mass for its self-gravity to overcome rigid body forces (is an idealization of a solid body of finite size in which deformation is neglected. In other words, the distance between any two given points of a rigid body remains constant in time regardless of external forces exerted on it.) so that it assumes a hydrostatic equilibrium (nearly round) shape; and has cleared the neighbourhood (of its own orbital zone, meaning it has become gravitationally dominant, and there are no other bodies of comparable size other than its own satellites or those otherwise under its gravitational influence) around its orbit; –or

PLANET: –or within another system, is in orbit around a star or stellar remnants;

PLANET: –or within another system, is in orbit around a star or stellar remnants; has a mass below the limiting mass for thermonuclear fusion of deuterium; and

PLANET: –or within another system, is in orbit around a star or stellar remnants; has a mass below the limiting mass for thermonuclear fusion of deuterium; and is above the minimum mass/size requirement for planetary status in the Solar System.

PLANET: –a celestial body that, within the Solar System, is in orbit around the Sun;orbit has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape; andrigid body forces has cleared the neighborhood around its orbit; –Or within another system, is in orbit around a star or stellar remnants; has a mass below the limiting mass for thermonuclear fusion of deuterium; and is above the minimum mass/size requirement for planetary status in the Solar System. THIS is what you wrote:

Components of the Solar System The vast majority of the Solar System’s mass resides in the Sun –All the planets, asteroids and comets make up less than 1/700 of the mass of the Solar System!

Components of the Solar System The vast majority of the Solar System’s mass resides in the Sun –All the planets, asteroids and comets make up less than 1/700 of the mass of the Solar System! The rocky inner planets (Mercury, Venus, Earth and Mars) are called terrestrial planets

Components of the Solar System The vast majority of the Solar System’s mass resides in the Sun –All the planets, asteroids and comets make up less than 1/700 of the mass of the Solar System! The rocky inner planets (Mercury, Venus, Earth and Mars) are called terrestrial planets The gaseous outer planets (Jupiter, Saturn, Uranus and Neptune) are the Jovian planets

Components of the Solar System The vast majority of the Solar System’s mass resides in the Sun –All the planets, asteroids and comets make up less than 1/700 of the mass of the Solar System! The rocky inner planets (Mercury, Venus, Earth and Mars) are called terrestrial planets The gaseous outer planets (Jupiter, Saturn, Uranus and Neptune) are the Jovian planets An asteroid belt separates the inner and outer planets

Components of the Solar System The vast majority of the Solar System’s mass resides in the Sun –All the planets, asteroids and comets make up less than 1/700 of the mass of the Solar System! The rocky inner planets (Mercury, Venus, Earth and Mars) are called terrestrial planets The gaseous outer planets (Jupiter, Saturn, Uranus and Neptune) are the Jovian planets An asteroid belt separates the inner and outer planets So what about PLUTO?

Pluto Pluto, considered a planet for 76 years, was reclassified as a dwarf planet in On August 24, 2006, The International Astronomical Union (IAU), the officially defines a "dwarf planet”

Dwarf planet: a celestial body that, within the Solar System, is in orbit around the Sun;

Dwarf planet: a celestial body that, within the Solar System, is in orbit around the Sun; has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape;

Dwarf planet: a celestial body that, within the Solar System, is in orbit around the Sun; has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape; has not cleared the neighbourhood around its orbit; and

Dwarf planet: a celestial body that, within the Solar System, is in orbit around the Sun; has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape; has not cleared the neighbourhood around its orbit; and is not a satellite The term "dwarf planet" applies only to objects in the Solar System. and is quite distinct from "planet" and "small solar system body".

Components of the Solar System The vast majority of the Solar System’s mass resides in the Sun –All the planets, asteroids and comets make up less than 1/700 of the mass of the Solar System! The rocky inner planets (Mercury, Venus, Earth and Mars) are called terrestrial planets The gaseous outer planets (Jupiter, Saturn, Uranus and Neptune) are the Jovian planets An asteroid belt separates the inner and outer planets The outermost icy planet, Pluto, is in a class called Trans-Neptunian Objects (TNO)

Beyond Neptune Trans –Neptunian Objects These objects (known as TNO) are nearly the same size as Pluto and are beyond Neptune's orbit The outermost icy planet, Pluto, is in a class called

The Kuiper Belt Outside the orbit of Neptune lies the Kuiper Belt –Located around 40 AU from the Sun –TNO’s are found here –Many bodies smaller and larger than Pluto have been found here So is Pluto really a planet?

Oort Cloud SO what is next? Comets also are cosmic debris, probably planetesimals that originally resided in the vicinity of the orbits of Uranus and Neptune rather than in the warmer regions of the asteroid belt. Thus, the nuclei of comets are icy balls of frozen water, methane, and ammonia, mixed with small pieces of rock and dust, rather than the largely volatile-free stones and irons that typify asteroids.

Oort Cloud SO… In the most popular theory, icy planetesimals in the primitive solar nebula that wandered close to Uranus or Neptune but not close enough to be captured by them were flung to great distances from the Sun, some to be lost from the solar system while others populated what was to become a great cloud of cometary bodies, perhaps 10 trillion in number. Such a cloud was first hypothesized by the Dutch astronomer Jan Hendrik Oort.

Oort Cloud Oort Cloud In Dr. Jan Oort noticed that: – No comet has cometbeen observed with an orbit that indicates that it came from interstellar space – There is a strong tendency for aphelia of long period comet orbits cometto lie at a distance of about 50,000 AU – There is no preferential direction from which comets comecomets

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