The Solar System is a gravitationally bound, multi object system of the Sun and all the objects that orbit it, which system is believed to have been created about 4.6 billion years ago. The largest amount of mass (about 99.8 percent) in this system lies with the Sun, with most all of the remaining mass contained in the planet Jupiter.

The celestial equator is the plane of the Earth′s equator that has been extended outward in all directions. (For more information: Celestial Equator)

The ecliptic is the plane of the Earth′s orbit around the Sun. Additionally, most all of the major bodies of the solar system, including the planets and most planetary moons lie on or within a few degrees of inclination from the ecliptical plane.

To illustrate, it can be said that our solar system it is like a pool of water with eight balls (planets) floating on the water surface (the ecliptic). From varying distances, all of these balls in the pool are circling (orbiting) a central vortex (the sun) in the pool. Furthermore, each of the balls have varying amounts of air inside of them which causes them to float at differenct levels (inclination) on or within the water. (For more information: Ecliptic)

The Sun, as see from above its north pole, rotates in a counterclockwise rotation. All of the eight planets orbit the sun in a counterclockwise rotation, which is called a prograde rotation.

All of the planets along the ecliptic rotate on their own axis, show as blue lines through the planets. Except for Venus and Uranus, the planets rotate the same direction as Earth does, which when looking down from above the north pole, is counterclockwise or in prograde motion. Venus and Uranus, however both rotate clockwise or retrograde.

Furthermore, each planet has its own an axial tilt, also known as the obliquity, which is the amount of the angle between its orbital plane (the ecliptic) and its rotational axis. The Earth currently has an obliquity of 23.4 degrees axial tilt.

More information about the planetary objects are found in the links below.

The ecliptic, as seen from earthbound viewers, is the line that can be drawn though the sun, the moon and the planets as they traverse the sky. Also, the ecliptic is an imaginary line forming a great circle overhead on the celestial sphere representing the apparent annual path of the sun, which path forms a circle that subsequently creates the ecliptic plane. (For more information: Celestial Sphere)

The planetary-mass object includes: planets, dwarf planets and moons. Planets and dwarf planets orbit the sun, but moons orbit other solar system objects. The planets and most of the moons are found on the ecliptic.

Other planetary mass objects orbit the sun in orbital paths other than on the ecliptic. This type of planetary mass objects include all of the dwarf planets.

A planetary-mass moon is a planetary-mass object that is also a natural satellite. They are large and ellipsoidal (sometimes spherical) in shape. Two moons in the Solar System, Ganymede and Titan, are larger than the planet Mercury, although less massive than Mercury. Seven of this solar system′s moons are larger and more massive than the dwarf planet Pluto.

From the Sun, the first four planetary-mass objects, which are not moons, are the inner planets which are composed primarily of rock and metal. These four are designated as terrestrial planets. From the sun, these planets as seen in the next photo are from left to right: Mercury, Venus, Earth, Mars.

Next, there is an expansive asteroid belt that separates the terrestrial planets from the outer four planets.

Then, the next four planetary-mass objects, which are all substantially larger and more massive than the terrestrial planets, are the four giant planets located in the outer solar system.

The giants as seen below are, from left to right: Jupiter, Saturn, Uranus, Neptune.

Jupiter and Saturn are both Gas Giants, composed primarily of hydrogen and helium, while Neptune and Uranus are Ice Giants, composed of water, ammonia and methane.

All eight planets have nearly circular orbits, all circle the Sun in orbits that are very close to the ecliptical plane, and except for Mercury and Venus, the next six planets all have moons which orbit them.

In our solar system, all planets are on the ecliptic. If a planetary-mass object it is not on the ecliptic, then it can not correctly be called a planet.

1. Orbit the Sun on or very near to the Ecliptic.

2. Have enough mass to achieve hydrostatic equilibrium and assume a nearly round shape, but not necessarily enough mass to cause thermonuclear fusion;

3. Has cleared and dominates its orbit and does not share the orbit with other celestial objects.

Mercury

Venus

Earth

Mars

Jupiter

Saturn

Uranus

Neptune

Other celestial objects that orbit the sun that are not on the ecliptic are call dwarf planets. Too, a dwarf planet may or may not have cleared the neighborhood around its orbit. Dwarf Planets are smaller than 2000 miles across the equatorial diameter.

There are 5 officially recognized dwarf planets in the solar system and are found in the outer solar system, except for Ceres which is located in the asteroid belt. Other celestial objects, with additional observation and study may soon be recognized as dwarf planets.

Pluto has been declassified as a planet and designated as a dwarf planet, because it does not meet the requirements for being called a planet.

For instance, the orbital path of Dwarf Planet Pluto does not lie in the same plane as the eight planets, but is inclined at an angle of 17 degrees. Too, its orbit is also more oval-shaped, or elliptical, than those of the planets. Further, it has not cleared it′s orbit of other celestial objects.

There are six more objects in our solar system that are almost certainly dwarf planets and there may as many as 10,000 objects yet to examine.

Of the dwarf planets only 2 have been visited by space probes, during the NASA Dawn mission which spacecraft entered orbit of Ceres on 06 March 2015 and a separate mission, New Horizons spacecraft which reached Pluto on July 14, 2015.

1. A dwarf planet is a celestial body, usually a small planetary mass object that is in direct orbit of the Sun, that may almost meet the requirement of a true planet but falls short in one or more of the requirement for a planet.

2. Dwarf planets have enough mass to achieve hydrostatic equilibrium and assume a nearly round shape, either spheroid or ellipsoid.

3. Dwarf planets can not be a moon or satellite of another planet.

4. Dwarf planets usually have an orbit that only crosses the ecliptic.

5. Dwarf planets usually fail to clear the neighborhood around their orbit.

Too, many more dwarf planets, possibly as many as 200 are believe to exist in the outer solar syatem in the neighborhood of the Kuiper belt.