Dating winds of wander
However, the preliminary results from the Galileo probe show only faint indications of clouds (one instrument seems to have detected the topmost layer while another may have seen the second).But the probe's entry point (left) was unusual -- Earth-based telescopic observations and more recent observations by the Galileo orbiter suggest that the probe entry site may well have been one of the warmest and least cloudy areas on Jupiter at that time.
This layer probably also contains some helium and traces of various "ices".Data from the Galileo atmospheric probe also indicate that there is much less water than expected.The expectation was that Jupiter's atmosphere would contain about twice the amount of oxygen (combined with the abundant hydrogen to make water) as the Sun.What we see when looking at these planets is the tops of clouds high in their atmospheres (slightly above the 1 atmosphere level).Jupiter is about 90% hydrogen and 10% helium (by numbers of atoms, 75/25% by mass) with traces of methane, water, ammonia and "rock".Galileo's outspoken support of the Copernican theory got him in trouble with the Inquisition.
Today anyone can repeat Galileo's observations (without fear of retribution :-) using binoculars or an inexpensive telescope.
It is still regularly observed by the Hubble Space Telescope.
The gas planets do not have solid surfaces, their gaseous material simply gets denser with depth (the radii and diameters quoted for the planets are for levels corresponding to a pressure of 1 atmosphere).
Jupiter is the fifth planet from the Sun and by far the largest.
Jupiter is more than twice as massive as all the other planets combined (the mass of Jupiter is 318 times that of Earth).
Above the core lies the main bulk of the planet in the form of liquid metallic hydrogen.