What is the difference between a gas giant and a failed star?

Gas giants and failed stars are two types of objects found in our universe, but they have significant differences. Gas giants are a type of planet that consists mainly of hydrogen and helium gases. They are much larger than Earth and have no solid surface. Jupiter and Saturn are two examples of gas giants in our solar system.

Failed stars, on the other hand, are objects that are not quite massive enough to initiate nuclear fusion in their cores, which is the process that powers stars. They are also known as brown dwarfs and are often referred to as 'failed stars' because they share some characteristics with stars but don't have enough mass to ignite fusion reactions. Brown dwarfs are much larger than gas giants and emit a small amount of heat and light due to residual heat left over from their formation.

The key difference between gas giants and failed stars is that gas giants are planets, while brown dwarfs are not. Gas giants orbit stars and are formed in a similar way to other planets in a solar system, while brown dwarfs are formed like stars through the collapse of gas and dust, but lack the mass to initiate fusion reactions. Brown dwarfs are often referred to as 'sub-stellar objects', meaning they are somewhere between a planet and a star in terms of size and characteristics.

In summary, gas giants and failed stars are both fascinating objects in the universe, but they have different origins and characteristics. Gas giants are planets made up mostly of gas, while failed stars are sub-stellar objects that share some characteristics with stars but do not have enough mass to ignite fusion reactions.