This is a drawing which illustrates the composition of Neptune's atmosphere relative to other possibilities for planets.
Click on image for full size
A Look at what Neptune's Atmosphere is Made of
The atmosphere of Neptune is very similar to that of Uranus, and unlike that of Saturn and Jupiter. On Jupiter and Saturn, the atmosphere is mostly composed of the simple molecules hydrogen and helium. The atmosphere of Neptune contains more of the complex molecules such as methane gas, ethane gas, acetylene, and diacetylene. These constituents collectively are known as "hydrocarbons".
Hydrocarbons form hazes of smog high in the upper atmosphere. There are clouds of methane ice low in the atmosphere.
Neptune's atmosphere originally formed from complex molecules and ice, rather than the simple molecules of which Jupiter and Saturn formed.
You might also be interested in:
This image of Neptune uses false colors to show where the smog is. The smog of Neptune can be seen in red along the edge of the image. These hazes of smog are found at very high altitudes, over the clouds...more
The giant planets have definitely changed since their formation. But how much remains to be seen. Most of the original air of the giant planets remains in place. (The earth-like planets lost most of their...more
The air of Neptune is extremely cold, with temperatures of -270 degrees to -380 degrees. The air is made of complex molecules, the same sort of molecules that we see coming out of cars on earth in the...more
Like Jupiter and all the giant planets, Neptune's appearance shows a striped pattern of clouds. Other cloud shapes seen over time include a small dark spot, the "scooter" and the Great Dark Spot. The Great...more
Neptune's atmosphere shows a striped pattern of clouds. This cloud pattern is very similar to that of Jupiter and Saturn. Neptune even has a Great Dark Spot similar to Jupiter's Great Red Spot. The history...more
This image shows the new Great Dark Spot of Neptune, which was discovered using the Hubble Space Telescope. The image shown here, shows a "hole" in the clouds of Neptune in pink, in the northern hemisphere,...more
This image shows some clouds known as "cirrus" clouds, extending for many kilometers across the face of Neptune. These clouds are very high up, for they can be seen to cast shadows on the lower clouds,...more
Scientists think that the solar system formed out of a spinning cloud of hydrogen and helium gas. Because the cloud was spinning, it flattened into a frisbee shape, just like a ball of pizza dough becomes...more