Solar System – Formation, Evolution & Fate

How our solar system came into existence? How did the sun form? How everything will end? This blog will help to answer these basic curiosities about our solar system.

The planetary system we call solar system is located in an outer spiral arm of the Milky Way galaxy.

Our Solar system consists of our star, the Sun and everything is bound to it by gravity – the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune, dwarf planets such as Pluto, Dozens of moons and millions of asteroids, comets and meteorites.

Our solar system extends much farther than the eight planets that orbit the Sun. The solar system also includes the Kuiper Belt that lies past Neptune’s orbit. The end of the solar system is about 122 astronomical units (AU) away from the sun, where one AU is 93 million miles (150 million kilometers). That’s about three times as far out as Pluto, which is about 40 AU from the sun, or about six times farther away from Earth than Neptune’s orbit.

The timeline of solar system dates back to 5 billion years from now when the whole system was just a huge clump of dust and gases. The cloud collapsed, possibly due to the shockwave of a nearby exploding star, called a supernova. When this dust cloud collapsed, it formed a solar nebula—a spinning, swirling disk of material.

At the center, gravity pulled more and more material in. Eventually the pressure in the core was so great that hydrogen atoms began to combine and form helium, releasing a tremendous amount of energy. With that, our Sun was born, and it eventually amassed more than 99 percent of the available matter.

Matter in the disk was also clumping together and smashed into one another forming larger and larger objects. Some of them grew big enough for their gravity to shape them into spheres, becoming planets, dwarf planets and large moons.

Structure of Solar System

The way planets are arranged is due to the way the solar system formed. Near sun only rocky bodies can withstand the heat and immense radiation from it. For this reason, the first four planets—Mercury, Venus, Earth and Mars—are terrestrial planets. They’re small with solid, rocky surfaces. The Sun sent out energy and particles in a steady stream, called stellar winds. These winds proved so strong that they blew off most of the gases of the four planets closest to the Sun, leaving them smaller, with only their rocks and metals intact. That’s why they are called rocky, or terrestrial, planets. 

Meanwhile in the outer orbits of solar system, gas giants took the place where the heat and radiation from sun is less and bodies can form larger structure than the ones near to sun. Gravity pulled the materials together in faraway orbits, and that is where we find gas giants Jupiter and Saturn and ice giants Uranus and Neptune.

Fate of Solar System

Every star dies when they don’t have enough fuel to burn in their core. Our sun is no different and will face the same fate which other stars face. In around 5 billion years from now, our Sun will enter into red giant phase where it will expand like a hot air balloon and its surface will extend till the orbit of earth and our planet will be doomed forever by the sun which has provided the energy to sustain life on earth for billions of years.

Mars will be too hot – too hot! Europa will finally have sea as the heat from sun will melt the icy layer. Saturn will come into habitable zone and Titan (moon of Saturn) will have a good temperature for humans to live in and it might look like earth. Our sun will spend approximately a few thousand to 1 billion years as a red giant.

Once this phase is complete our sun will become a white dwarf and in some quadrillion years it will become a Black Dwarf star. And this will be the end of our Solar System.

It is also expected that our Sun – White Dwarf will collide with a star in next 30 trillion years as well.