The solar system, the universe and the galaxies fascinate me. The scale on which these things function is unimaginable; we talk about light years and the possibility of black holes, and dark matter like they are things we know everything about - yet we as humans know nothings. There are hundreds of billions of planets in thousands of galaxies, all contained in a system that is expanding faster than the speed of light.

In this article we are going to take a basic look at how space exists, from our own planet to our solar system, then our galaxy and onto other galaxies.

Planet Earth

Our home planet, the only one we know of which supports any kind of life - be it regarded as intelligent or not (I’m including humans in that one). It is the center of our universe, but the center of no one else’s. We are unique as we are close enough to our closest star, the sun, to be kept warm but not too close as to vaporize all the liquid on the planets surface. We are the goldilocks planet, and we have yet to find a planet which is similar to ours. So many things are unique about our planet it is quite scary to think how fragile our existence is on the planet. Modern societies are only 7 thousand years old, and we only discovered space travel fifty or so years ago. We are damaging our planet, probably irreversibly, but in the grand scheme of the universe - it is but a speck of dust.

The Solar System

Our solar system consists of the Sun, our closest star, and the planets orbiting it.  The planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. After that come the dwarf planets including recently relegated Pluto - who lost their planet status as they weren’t big enough to compete in a modern universe! The first four planets are terrestrial - that is they are made from metal and rock. We are one of those planets are we are tiny compared to the four outer gas giants, especially the two biggest Jupiter and Saturn. Those two planets are made mostly from hydrogen and helium, and Uranus and Neptune are made from ice such as Water, ammonia and methane - those are known as the ice giants. We also have an asteroid belt after Mars. After Neptune the Kuiper belt is present and several dwarf planets including Pluto, Hume, Makemake and Eris. They are know as dwarf planets as they have been rounded by their gravity, as opposed to existing as a piece of rock like an asteroid would.

Beyond our Solar System

Beyond our solar system is the rest of the Milky Way, so called because astronomers noticed the milky line across our night sky. In that line it becomes difficult, if not impossible, to distinguish between different starts and so it tells us that our galaxy exists rather like a disk, instead of being equally distributed. Our galaxy is around 120,000 light years across. That means that at the speed of light, it would take 120 thousand years to cross the galaxy. It contains around 400 billion stars and at least 200 billion planets. By estimations of the number of planets, there could be up to 10 billion planets that are in potential habitable zones - i.e. they could or already do support life. Our galaxy moves at around 600km per second, and rotates every 15- 50 million years. The age is estimated at 13.2 billion years, pretty much dating from the start of the universe. Our galaxy is structured in a spiral shape. With the solar systems orbiting and core of gas and stars. We cannot look at our solar system from afar as yet, so all we can do is model its probable structure.

Who else is in the neighborhood - Andromeda

The Andromeda Galaxy is the closest to our own in terms of distance and that it is a spiral galaxy, but in real terms it is incredible far away. Andromeda is around 2.5 million light years from earth, meaning that our images of the galaxy are 2.5 million years old - and incredible fact if you think about it. It is estimated to have a trillion stars, and so will have trillions of planets. Massive numbers and the potential for life, even advanced life, is great because of the sheer large numbers. An interesting fact is that our Galaxy and Andromeda are expected to collide in 4.5 billion years, which isn’t that long if you consider we look at dinosaurs and early life existing billions of years ago.

Is there life out there?

Finding life is many scientists dream. But for most of us - we would only be really interested if we found life similarly developed to our own. I think we would be terrified if we found life more advanced than ours, and would take advantage of life less advanced than ours. If they lived on a planet with similar conditions to ours it would definitely change the course of our species history. However, travelling to any planet - even inside our solar system - is a challenge. So unless the "aliens" we discover have developed faster than light travel, we may only find out about them by listening to some million year old radio broadcast from the other side of the galaxy.

I think space, the solar system and the galaxy is interesting and I enjoy teaching it to pupils as part of my work. For me the most interesting aspect is the scale of space. When we look into the night sky we see light that is billions of years old, light older than man, life and sometimes even the formation of our planet and the solar system.

What do you think about space? Do you find it a fascinating topic? How was it taught to you at school? What do you feel is most interesting? Please comment below and if you need to join InfoBarrel there are links at the top of the page.