Ethan Kwan
April 13, 2021
The place we live
The solar system. Located in an outer arm of the Milky Way galaxy. Nine Eight planets, Over 200 moons, and a whole lot of asteroids, all held together by gravity. But how did it form?
The Formation of the Solar System
To understand the formation of the solar system, we need to go back 4.5 billion years, to a boring cloud of mostly hydrogen and helium. This cloud of gas needs something to disturb it a little, so it can get more exciting.
Light years away from the dust cloud, a star is running out of fuel. It implodes, and sends a shockwave through the galaxy. This shock wave hits this dust cloud, and the dust cloud starts to clump in where there is lots of gas. (Technically, it’s much more complex than that, but that would take too long to explain.)
The gas cloud collapses into many many many stars, but wet’s focus on one of the stars, the sun. The sun takes in 99.99% of all matter around it, finally getting hot enough to fuse hydrogen into helium in the core. The 0.01% remaining orbits around the newly formed sun, slowly flattening out, like how bakers twirl pizza dough until it gets flat.
This now flat disc consists of gas and rocks. Near the sun, the gas is blown away by the solar wind, and leaves the rocky materials behind. Slowly but surely, these rocks near the sun turn into small asteroids, that turn into protoplanets. In the outer regions of the solar system, gas builds up in clumps, forming the outer gas protoplanets.
The inner protoplanets move faster, so they have more collisions. These collisions kept happening, destroying most planets, leaving five major rocky planets: Mercury, Venus, Earth, Mars, and Theia. Theia shared Earth’s orbit and was about the size of mars.Eventually, the two planets collided, leaving a massive ring of debris around the young Earth, and turning the earth molten. The ring of debris slowly formed into the moon.
In the outer reaches of the solar system, gas planets formed, giving four main gas giants: Jupiter, Saturn, Uranus, and Neptune. Jupiter became the largest planet in the solar system, because it was the first to form. Saturn came next, followed by Neptune and Uranus.
Finally, the gas giants have formed: Jupiter, Saturn, Neptune, and Uranus – Wait, what? Isn’t Neptune supposed to be farther from the sun?
Well, it turns out that Uranus was the farthest planet from the sun. So what caused them to switch? Well, because of Jupiter and Saturn.
Jupiter and Saturn’s orbits drift apart very slowly, until they create a 2:1 resonance with each other. Each time Jupiter orbits twice, Saturn orbits once. The orbits of other gas giants become unstable, and Uranus and Neptune interact gravitationally, flinging Neptune into a wider orbit. This wider orbit has comets in it, and so Neptune flings them into the inner solar system.
This event is called the Late Heavy Bombardment(LHB), and happened about 3.85 billion years ago. During this interval, a large number of asteroids are theorized to have collided with the early terrestrial planets in the inner Solar System, including Mercury, Venus, Earth, and Mars. Comets are very rich with water, and brought it to the early inner planets. All of these planets received large amounts of water. So why is Earth the only liquid planet now?
Mars lost its water because it core lost activity, largely because of Mars’s smaller size compared to Earth, this also meant that Mars’s core became geologically dead. As a result of this, Mars lost its magnetic field, which meant that it lost its atmosphere; and because Mars lost its atmosphere, all the water vaporized and was lost in space. Today, only a remnant of the Martian atmosphere remains, mainly composed of CO2, it is around 0.6% as thick as Earth’s atmosphere.
As for Venus, its problem was it rapidly thickening atmosphere and its close proximity to our Sun. Unlike Mars, Venus is not in our Solar System’s habitable zone, and as a result of this, it would have been very hard for Venus to retain liquid water. During Venus’s early stages as a planet, it developed a thick CO2 atmosphere, just like Earth and Mars at that time. However as a result of Venus not being in the habitable zone, this CO2 atmosphere underwent a greenhouse effect, which meant that it was trapping heat from our Sun. This resulted in the surface temperature of Venus getting extremely hot, and all of the water evaporating and entering Venus’s atmosphere as water vapour.
Eventually, the eight planets settled into their orbits, leaving a lot of stuff behind. The asteroid belt, the Kuiper built, and the Oort Cloud, which is a cloud of material orbiting very far away.
That is the formation of the solar system. But how will it die?
The end of The Solar system
Our star is powered by nuclear fusion, and it turns hydrogen into helium in a process that converts mass into energy. Once the fuel supply is gone, the sun will start growing dramatically. Its outer layers will expand until they engulf much of the solar system, as it becomes what astronomers call a red giant.
And what will happen to the planets once the sun enters the red giant phase? The solar system’s denouement is still a subject of debate among scientists. Exactly how far the dying sun will expand, and how conditions will change, aren’t yet clear. But a few things seem likely.
The slow death will kill off life on Earth, but it may also create habitable worlds in what’s currently the coldest reaches of the solar system.
Any humans left around might find refuge on Pluto and other distant dwarf planets out in the Kuiper Belt, a region past Neptune packed with icy space rocks. As our sun expands, these worlds will suddenly find themselves with the conditions necessary for the evolution of life.
Let’s take a quick tour through our solar system in the last days of the sun.
Mercury
Throughout the history of the solar system, Mercury was baked by the sun. But even today, Mercury has some ice inside craters around the poles, where sunlight never touches. However, when the sun expands, it will eat up mercury like a very VERY slow version of the Death Star from Star Wars.
Venus
Many people consider Venus to be like Earth’s twin, because of their similar mass and size. However, the hellish atmosphere of Venus is nothing like Earth’s Goldilocks-perfect conditions. As the sun expands, it will blow away Venus’s atmosphere. Then Venus will also be consumed by the sun.
Earth
While the sun may have 5 billion years left before it runs out of fuel, life on Earth will likely be wiped out long before that happens. That’s because the sun is actually already growing brighter. By some estimates, it could be as little as a billion years before the sun’s radiation becomes too much for life on Earth to handle.
That might sound like a long time. But, in comparison, life has already existed on this planet for well over 3 billion years.
And, when the sun does turn into a red giant, the Earth will also be vaporized —perhaps just a few million years after Mercury and Venus have been consumed. All the rocks and fossils and remains of the creatures that have lived here will be gobbled up by the sun’s growing orb, wiping out any lingering trace of humanity’s existence on Earth.
But not all scientists agree with this interpretation. Some suspect the sun will stop growing just before fully engulfing our planet. Other scientists have suggested schemes formoving Earth deeper into the solar system by slowly increasing its orbit. Thankfully, this debate is still purely academic for all of us alive today.
Mars
Even our young sun’s radiation was too much for Mars to hold onto an atmosphere capable of protecting complex life. However, recent evidence has shown that Mars may still have water lurking just beneath its surface. Mars may escape the sun’s actual reach — it’s at the borderline — but that water will likely all be gone by the time the red giant star takes over the inner solar system.
The Gas Giant Planets
As our red giant sun engulfs the inner planets, some of their material will likely get thrown deeper into the solar system, to be assimilated into the bodies of the gas giants. However, the approaching boundary of our star will also vaporize Saturn’s beloved rings, which are made of ice. The same fate likely awaits today’s icy ocean worlds, like Jupiter’s moon Europa and Saturn’s Enceladus, whose thick blankets of ice would be lost to the void.
The new Habitable Zone?
Once our sun has become a red giant, Pluto and its cousins in the Kuiper Belt — plus Neptune’s moon Triton — may be the most valuable real estate in the solar system.
Today, these worlds hold abundant water ice and complex organic materials. Some of them could even hold oceans beneath their icy surfaces — or at least did in the distant past. But surface temperatures on dwarf planets like Pluto commonly sit at an inhospitable hundreds of degrees below freezing.
But by the time Earth is a cinder, the temperatures on Pluto will be similar to our own planet’s average temperatures today.
Conclusion
In conclusion, the solar system is a wonderful place, filled with eight planets, millions of asteroids, and a sun that keeps the whole thing warm. And now you know how it formed, and how it will end!
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