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We now offer the Cool It! card game in our Science Store. Cool It! is the new card game from UCS that teaches kids about the choices we have when it comes to climate change.

Evolution of Neptune's atmosphere, page 7
The Size of the Planet matters




Mercury
(small)

Venus
(medium sized)

Jupiter
(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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Neptune's Cirrus Clouds

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Neptune's Smog Hazes

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Discover Neptune

If you had a quiz question in school that asked what year Neptune was discovered, you'd probably choose 1846. But Neptune wasn't discovered the way all the other planets in our solar system were. Astronomers...more

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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