Poseidon

Planet with bright azure as the colour

Orbits are elliptic and distant from the solar

Satellite here larger than the dwarfs is Triton moon

Equinox occurs after four score years soon

Inkling of diamond rain is seen which is quite quaint

Dominated with ice with sunbeam unduly faint

Over here is the Great Dark Spot which is too odd

Neptune is the planet named after the Sea God