Thread: How is it possible that gaseous planets are entirely constructed of gas?

Scientists say that gaseous planets are entirely constructed of gas. During the formation of a gaseous planet, how do the gases form a sphere? Wouldn't there have to be a solid core that would create the gravity needed to pull the gases into a sphere?

The giant planets in our solar system are all believed to have cores of icy and rocky materials (in this case icy and rocky don't necessarily mean cold solid, they can also mean hot liquids) overlain with hydrogen and helium.
The giant plants have huge pressures in their interiors which may compress the cores into a solid.

The planets were formed from a rotating disc of gas composed mainly of hydrogen and helium. At the centre of the disc, the sun formed. The planets formed from the remainder of the disc. In the inner part of the disc, grains of dust formed which had a mainly rocky composition. This is because it was too hot for icy materials to form solid ices. The rocky dust then gathered together to form larger bodies, which also combined to form the terrestrial planets.
Further from the sun the disc was cooler, and so the grains of dust could also contain icy materials, notably water ice. This extra icy component led to the formation of icy-rocky bodies. These were so massive that the gas in the disc was gravitationally captured by them, and thus the giant planets were formed.