HOW AN ICE GIANT IS MADE

The ice giants formed around the Sun like their Solar System siblings

1 Cloud of gas and dust collapses

An interstellar cloud of gas and dust, known as a solar nebula, collapsed in on itself and began to spin. Our newborn Sun began to shine in the centre of this spinning disc as the temperatures and pressures triggered thermonuclear fusion.

2 Material comes together

Heavier materials in the spinning disc of gas and dust started to form into clumps. Closer to the Sun these materials included rock and iron, but beyond the frost line, which lies between the orbits of Mars and Jupiter, there were solid ‘ices’ like water, methane and ammonia.

3 Clumps collide and merge

Clumps combined through collisions and started to become the building blocks of planets. Over millions of years these planetesimals increased in size through more collisions. The four giant planets beyond the frost line grew big enough to amass hydrogen and helium.

4 The planets take shape

Solar wind from the Sun dispersed any remaining gas from the Solar System, and planet formation was almost done. Uranus and Neptune are thought to have formed after the dust was swept away from the inner Solar System to its outer regions.

5 Planets get in formation

Uranus and Neptune might have formed farther in between Jupiter and Saturn and later migrated out to their final positions today over hundreds of millions of years. Uranus was likely hit by an impactor when its moons and rings were still forming.