Indira Gandhi Planetarium, Lucknow Veer Bahadur Singh Planetarium, Gorakhpur        Aryabhatt Planetarium, Rampur


Neptune is the eighth and farthest planet from the Sun in our Solar System.Neptune is similar in composition to Uranus, and both have compositions which differ from those of the larger gas giants.The interior of Neptune, like that of Uranus is composed of ices and rock. Its atmosphere contains hydrogen and helium with enough methane to give it a bluish tint.  
It has a diameter of about 55,528 km. And the period of rotation and revolution are 16.11 hours and 163.72 Earth year respectively.

Internal Structure of Neptune:

The core of Neptune is probably composed of liquid rock with a 6,200-mi radius and represents 45% of the planet's mass that is composed of silicate rock and water ice.
Above the core is a darker and hotter region, condensed into a superheated liquid mantle, where temperatures reach 2,000 K to 5,000 K. The mantle is equivalent to 10 to 15 Earth masses and is rich in water, ammonia and methane.
Surrounding the mantle is a atmosphere consisting of hydrogen, helium and methane gas and the concentration of these gases goes on decreasing as altitude increases.

Atmospheric Composition of Neptune:

Components Percentage Composition  
hydrogen 80±3.2  
helium 19±3.2  
methane 1.5±0.5  
hydrogen deuteride ~0.019  
ethane ~0.00015  
ammonia (ices)  
water (ices)  
ammonium sulphide (ices)