Saturn is the sixth planet from the Sun and the second-largest in the Solar System, only behind Jupiter. It is a gas giant – meaning it is almost entirely made of hydrogen and helium – with an average radius about nine times that of Earth and is best known for its prominent ring systems. However, this planet – which is close enough to be seen in the night sky this month – has not always looked the way it does today.
It was revealed during Brian Cox’s new BBC Show ‘The Planets” how NASA discovered it was a very different planet 4.5 billion years ago.
Dr Cox told viewers earlier this month: “If an atmosphere gets big enough, it can transform a whole planet.
“Within just a few million years of its birth, Saturn had grown as large as it could, from rock and ice alone.
“And now it turned to another building material – the hydrogen and helium gas left over from the formation of the Sun.
If an atmosphere gets big enough, it can transform a whole planet
“This gas would have been too light for the worlds of the inner Solar System to hold on to.”
Dr Cox went on to explain how the forces of Saturn pulled in the gases.
He detailed: “Saturn’s great mass created gravitational forces powerful enough to draw it in.
“Trillions upon trillions of tonnes of hydrogen and helium gas began to envelop the planet.
“As this new atmosphere grew, it transformed the surface below.
“Enormous pressures created by the weight of this gas, heated rock and ice so much, they began to glow.”
Dr Cox then revealed how this process changed Saturn entirely.
He continued: “As Saturn matured, the pressure at the surface rose to ten million times the atmospheric pressure on Earth.
“Under that kind of pressures, matter behaves in extremely strange ways.
‘The very idea of a surface becomes meaningless and Saturn was transformed from an icy rocky world into a completely different class of planet – a gas giant.”
It was revealed during the same documentary how NASA also found Neptune was once “bursting with activity”.
Dr Cox revealed: “Neptune – 17 times the mass of the Earth and even more massive than Uranus.
“But in contrast to its sister planet, Neptune’s atmosphere is bursting with activity.
“What we found was a planet of extreme weather, where high altitude winds whip white methane clouds at speeds of over 2,000 km/h.
“Those are the highest wind speeds anywhere in the Solar System.”
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