Neptune is the other sub-jovian planet, along with Uranus. It presents a number of differences from either Jupiter or Saturn. It is quite a bit colder and denser. The blue color of the clouds is due to the presence of methane gas in the atmosphere. We believe there is an appreciable layer of ice within the interior of the planet. With no layer of metallic hydrogen to generate a magnetic field, Neptune apparently uses a layer of highly compressed water as the electrically conducting fluid.The existence of the eighth planet was revealed to humans in the year 1846. Two men had independently calculated the supposed planet’s position using its gravitational influence on Uranus. Who discovered Neptune? Was it John C. Adams or Urbain Leverier? I guess the answer to that depends on whether you are French or a loyal British subject. Although the first person to see Neptune, and know that it was a planet, was Johann Galle?
The equatorial radius of Neptune is 24,766 km.This makes the planet a little less than four times larger than Earth
Neptune spins in 16h 6m at the equator. That’s not quite as fast as Jupiter or Saturn, but faster than any of the terrestrial planets.
Neptune orbits the Sun at an average distance of 30.0 A.U. It receives about a thousand times less radiative energy from our central star.With an orbital period of 165 years, Neptune has just now orbited once around the Sun since being discovered in 1846.
Neptunes' outermost layers consist of hydrogen and helium gas. But below that, there is a deep layer of ice, primarily H2O, but with methane and ammonia in the mix as well.There is also a slight amount of other, more exotic compounds.
Uranus has a strange, tilted magnetic field that is off-centered as well. It is thought that the conducting fluid that create Uranus’ magnetic field is highly compressed water.