The Life Cycle of the Solar System
Everything in the Universe is born and destroyed, and the Solar System is no exception, running through the life cycle of birth, development, decline, old age and death.
The Sun formed around 4.6 billion years ago from a very fine dust and gas cloud. At the centre of the cloud, due to gravity, matter became denser and the temperature increased, until it triggered nuclear fusion, that is, energy production. Thus the forerunner of our Sun was born. The remaining dust continued to form lumps which collided more and more frequently, thereby increasing in size, and resulting in the formation of the planets, moons, dwarf planets and comets.
Based on calculations, the solar system is now in its ‘adult’ phase, after which it will start to decline. It will die in about 7–8 billion years.
The birth of the Sun
About 4–5 billion years ago, dust particles in a dust
cloud started forming clumps due to the pull of gravity
and increasingly frequent collisions until they formed
a disc-shaped cloud. At the centre, matter became denser and the temperature increased. Thus the forerunner of our Sun was formed. Planets and moons were formed by the collision of the clumps orbiting in the outer parts of the cloud.
The ‘adult’ Sun
As the centre of the cloud collapsed, causing the temperature to rise high enough for nuclear fusion to start, a new star, the Sun, began to shine brightly. Today the Sun is a steady energy producer: nuclear fusion in its core transforms hydrogen into helium.
The decline: The red giant
About 5 billion years from now, when the nuclear fusion of hydrogen stops in its core, the core will shrink, while the outer layers will inflate, and the Sun will become a red giant. It will be 256 times its current size. After engulfing Mercury and Venus, the Sun will probably engulf the Earth as well.
The Old Sun
After a further 2 billion years, the outer layers of the Sun will gradually separate from its core, forming a planetary nebula.
The Death of the Sun
When the fuel of nuclear fusion is used up, the Sun will shrink and become a white dwarf. In the last phase of its life cycle, it will lose all its remaining heat energy and become a dark and cold black dwarf.
The ultimate fate of the solar system’s planets
When the Sun inflates to become a red giant, it will engulf the innermost planets, and the outer planets will also fragment due to changing gravitational effects.
At the last stage of its life the Sun becomes a white dwarf, with only the remnants of the planets orbiting the corpse of what was once a star.
The life cycle of stars
The greater the mass of a star is, the faster it converts matter into energy. As a result, stars with large masses have a shorter lifetime than those with smaller masses. Stars similar to the Sun have a lifespan of approx. 10 billion years, while that of Sirius for example, with a mass that is 2.35 times larger than that of the Sun, is some 100 million years.
Our Solar System
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Our Solar System
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