Large celestial bodies in orbit around a star, composed of rock, metal, or gas.

The nine planets in the solar system are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto.

The inner four, called the "terrestrial planets" are small and rocky, and include the planet earth.

The outer planets, with the exception of Pluto, are called the major planets, and consist of large balls of rock, liquid, and gas; the largest is Jupiter, which contains a mass equivalent to 70% of all the other planets combined.

Planets do not produce light, but reflect the light of their parent star.

The planets are illustrated at the sight indicated below and links are available for more details about their Greek and Latin myths, symbolisms (system of symbols), and scientific information.

Click on this link for significant images and more detailed information about planets.

A planet that orbits a star other than the Sun: Exoplanets are detected by observing their star's "wobble" which the exoplanet's gravitational attraction causes.

Scientists have spied a new exoplanet and not only is it the biggest one yet, but it’s also moving in the wrong direction

Unlike other planets, which orbit in the same direction as their stars rotate, "WASP-17" moves in the opposite way, according to a study published in Astrophysical Journal.

Instead of traveling around its host star in the same direction the star spins, like all other known planets, but this abnormal planet is orbiting backwards. Scientists think the renegade orb, named WASP-17, got flipped around during a near collision with another planet during its early development.

Planets are born from the same ball of rotating gas that creates their parent star, which is why they usually orbit, and spin, in the same direction as their "mother star". While WASP-17 is the first planet known to orbit backwards, some planets in our own solar system, such as Venus, are spinning backwards. Like WASP-17, Venus may have experienced some kind of collision during its early history, which threw it into an unusual spin.

Researchers at "South African Astronomical Observatory" discovered the new exoplanet 1,000 light years away from Earth. In addition to its surprising orbit, the exoplanet stands out because of its size; in that, being only half the mass of Jupiter but twice its volume, the researchers claim WASP-17 is now the largest known planet.

WASP-17 marks the 17th exoplanet discovered by the "Wide Angle Search for Planets", or WASP project, conducted by eight universities in the U.K.

Because exoplanets don’t give off any light of their own and are usually obscured by their super-bright host stars, the scientists find exoplanets by scanning hundreds of thousands of stars, looking for the subtle dimming that occurs when a planet passes in front its parent star.

A planet that can support life: A Goldilocks planet is neither too hot nor too cold, neither too big nor too small, and neither too near its star nor too far.

A Goldilocks planet is one whose size, temperature and composition are all just right to maintaine life.

Any planet whose orbit is smaller than that of Earth: The result is that Venus and Mercury are the two inferior planets of the solar system.

Passively drifting and wandering in the sky unit.

Mercury, Venus, Earth, and Mars.

The orbits and positions of the planets or "wanderers" could not be accurately accounted for before the invention of the telescope although star positions were known.

Understanding came with the revolutionary work of Galileo, Brahe, and Kepler which, together with Newton's contributions, finally swept away the Greek concept of an earth-centered universe and established the present model of the solar system.

The Greeks had simplified celestial mechanics according to the simple doctrine that "matter behaves according to nature."