What are Planet and its type

Planet: 

# A celestial body moving in an elliptical orbit around a star is known as a planet.

# The planets of our solar system are divisible in two groups:

# the planets of the inner circle (as they lie between the sun and the belt of asteroids) or the inner planets or the ‘terrestrial planets’ (meaning earth-like as they are made up of rock and metals, and have relatively high densities) and

# the planets of the outer circle or outer planets or the ‘gas giant planets’ or the Jovian planets – meaning Jupiter-like.

# The inner circle consists of four planets (Mercury, Venus, Earth and Mars) having smaller and denser bodies while the outer circle comprises four planets (Jupiter, Saturn, Uranus, and Neptune) having a larger size and less dense materials and have a thick atmosphere, mostly of helium and hydrogen

# Jovian planets are more like the sun than like the terrestrial planets.

# If we take Jupiter, the biggest planet, as the centre of the planets of our solar system, the size of the planets becomes smaller as we go away from either side of Jupiter (Mars being the exception).

# The orbits of the planets are nearly circular, but many comets, asteroids, and Kuiper belt objects follow highly elliptical orbits.

An Astronomical Unit (AU) is the average distance between Earth and the Sun, which is about 150 million km.