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Evolution of Neptune's atmosphere, page 5
The Size of the Planet matters


(medium sized)

(very large)

Hydrogen (H) less than 1 hour days over the age of the Universe
Helium (He) roughly 1 day 100 times the age of the solar system over the age of the Universe
Oxygen (O) 800 million years over the age of the Universe over the age of the Universe

This table shows the time it takes, on average, for a few common atmospheric gases to escape the gravity of a planet. The table shows that as the planets get larger (more massive), it is harder for the gases to escape. The table shows that the average time for any gas to escape from Jupiter's gravity is much too long. The same is true for all the Giant planets. Therefore it is likely that all the gases in Neptune's atmosphere are probably the original gases swept up by the proto-Neptune.

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A Look at the History of Neptune's Atmosphere

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

Neptune's Present Great Dark Spot

This image shows the new Great Dark Spot of Neptune, which was discovered using the Hubble Space Telescope. The image shown here, shows a large "hole" in the clouds of Neptune in pink, in the northern...more

Neptune's Cirrus Clouds

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

Neptune's Smog Hazes

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. This smog haze is found very high up in the atmosphere, over the clouds...more

A Look at Neptune's Clouds

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

How the Solar System may have formed from a spinning cloud

Scientists think that the solar system formed out of a spinning cloud of hydrogen and helium molecules. Because the cloud was spinning, it flattened into a frisbee shape, just like a ball of pizza dough...more

Discover Neptune

Neptune was discovered in 1846. But it wasn't discovered using a telescope. Scientists used math instead! They watched Uranus and saw that its orbit was doing weird things. They knew another planet had...more

The Source of Heat from Within Neptune

The picture shows places on Jupiter which are hot. Jupiter is a very warm place, as shown in the picture, sort of like a warm log in the fireplace which gives off heat. Like Jupiter, Neptune also gives...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA