The Solar System: Our little log cabin

The Solar System: Our log cabin, away from it all

Far away from it all, away from all the rage;
a quiet place, that’s warm and safe.

Our Sun. There are many stars like it, but this one is ours. It’s about average size, and a bit basic, being made of almost entirely hydrogen and helium, with not a lot of metal or anything else fancy in it. However, even it still manages to burn at about 5,000 degrees celsius on the outside and 12 million at the center, creating 300 million tonnes of helium every second. Its been doing so for about 5 billion years, and will probably continue to do so for about 7 billion more. Let’s dive in, to our Solar System.

Our Solar System: A beginner’s guide

A picture of our Solar system, focussing on more than just the planets (everyone knows them). The Sun is also surrounded by a big cloud of asteroids far beyond the planets called the Kuiper Belt – and some of these are massive, such as Pluto. There are a few objects out even further than this, such as comets which go way out into space, only being pulled back by the Sun at the last possible moment (image Space Facts, Laurine Moreau).

The Solar system is the area of space around our Sun. The Sun is a star, just like the many other stars in our night sky, but much much closer, and therefore brighter. The solar system contains eight planets orbiting our Sun (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune). However, it also has a bunch of other objects much further out, including a few belts of asteroids that are much further out (such as the Kuiper Belt and the Oort cloud – Pluto is a part of these).

Our Solar System is certainly not a highlight of our galaxy. The spiral disk of our milky way has a lot going on, including some black holes right in the center. Our Solar System is just at the beginning of one of the bigger arms of the Milky Way. Not right in there, but not too far away on the outer rim. The Sun itself is a bit unusual, in that it’s a single star system, a lot of other systems are binary stars, or have a few stars in a patch orbiting each other. Our sun, not like that, is a bit off on its own, quite far away from any other stars. But it’s not super big, or super bright, or anything like that.

*Our Sun and Solar system are in one arm of the milky way galaxy. The big string of lights we see at night is an arm of the Milky Way*.

Formation of our Solar System

Our Solar System formed the same way that galaxies and other stars formed (see our post here). Bits of dust floating out in space slowly clumped together due to gravity and condensed into a star, with the leftover bits becoming the surrounding planets. The difference is scale, the Solar System used trillionths of the amount of dust that would be needed to form a galaxy. But the fundamental process is the same: dust clumping over time.

The disk of space dust that turned into our Solar System probably started spinning because of a nearby star exploding about 5 billion years ago. This spinning disk of dust slowly started to flatten and condense. Eventually, particularly dense bits, probably rocky asteroids, slowly started accumulating more of the dust around them until they formed clumps eventually turning into the planets we know and love. The biggest clump at the center eventually got big enough to become a star, our Sun. The closest planets (Mercury, Venus, Earth, Mars) are all rocky – this is because the early sun was very hot and gobbled up all the gas that was close to it. Only the further away planets (Jupiter, Saturn, Uranus, Neptune) managed to keep some gas for themselves and have lots of moons.

Pistols at dawn: The rivalry between our Sun and Jupiter

Jupiter and the Sun initially were competitors for who would become the dominant star in our solar system. Jupiter lost, however now he helpfully protects us from asteroids, which is very kind (image NASA/JPL).

The real excitement in our early Solar System was the race between Jupiter and the Sun on who was going to become larger. Early solar disks often have a few proto-stars, clumps of matter that are slowly combining, all competing to become big enough to be the first local star.

Sometimes, multiple clumps of dust in a system can become stars. If this happens you get what’s called a binary system. The closest star to Earth, Proxima Centauri, is actually a trinary system, with three stars, all orbiting each other. However mainly, one particular mass will win out. And when it gets a bit of a lead in terms of mass, it can use that to very quickly become much bigger, leaving the losers as large gassy planets.

That is exactly what happened with Jupiter. In the initial solar disk, Jupiter and the sun were pretty evenly matched in terms of who was going to become the first star. Obviously, the sun massively ended up winning, being vastly bigger.

However, we should still be very grateful for Jupiter – he protects us from asteroids. There are a lot of asteroids in our Solar System, often orbiting our Sun in a belt. They often gain a bit of momentum and escape and can hit one planet or another. Jupiter however, is generally big enough to capture the larger ones. Exactly how often and how much this happened in the early solar system isn’t well understood, but a decent-sized asteroid hitting an early forming planet can easily vaporize all the water on the planet, or make it lose most of its atmosphere. It’s very likely Jupiter has protected us from that fate many times over the history of our planet. We should probably be a bit more grateful.

Why should we care about our Sun?

There are images created by NASA of the start of a solar flare at our Sun, using different wavelengths of light. We normally think of our sun as just a uniform big ball, but it is not. The Sun has all sorts of internal structure, such as flares and explosions which constantly emerging and being destroyed (sometimes, with solar storms, they even reach earth and affect our telecommunications equipment). And they often look completely different depending on the frequencies you use to look at the Sun (see NASA’s Solar Dynamics Observatory for more).

We used to worship the sun. Almost every ancient civilization had some form of Sun god, an all-powerful bringer of life. In Ancient Greece, Apollo, their Sun god, had massive temples to his name. The Egyptians had Ra, a body of a man with a face of a falcon, that probably ended up almost having his own separate monotheistic religion, due to many ancient Egyptian’s fascinations with the Sun. However as time went on, and modern religion evolved, worship of the natural world went out of style. Now, most people probably don’t think much about the sun. It’s just something that’s there.

Imagine for a second the Sun disappeared. Within 8 minutes, once the last sent from the Sun to the Earth reached us, the sky would be dark. Darker than the darkest night, because moonlight would also disappear (moonlight is just reflected sunlight). Almost immediately the temperature of the Earth would start dropping, just like it does when the Sun goes down at night. But this time, it would never go up again. There would be no dawn.

Within a few days, the temperature would be below freezing, with most of the plant and animal life on Earth dead. Within a few months, the earth would be far below freezing. Almost the entirety of the human population would have died. Some of us might be surviving deep below the ground in bunkers warmed by petrol generators. But for the most part, life on earth would have ended. Some weird microbes might survive, but almost nothing else. We would pray for its return and tell stories about the days when the Sun graced us with her warmth.

Frankly, we here are The Universal Story think these cultures had a better understanding of the Sun. It is a glorious thing that, along with the Earth, has given us all that we value as a species – light, warmth, color, life. We should appreciate it a bit more.