How the Earth was born

In a previous post I wrote about how we discovered the age of the Earth, and I mentioned that our planet formed at the same time as the other rocky bodies in our Solar System.

I didn’t say HOW this happened though. So now I will.

Happy now?

How old is the Earth? And how do we know?

In 1650 the Archbishop James Ussher announced that the Earth was thousands of years old.

Almost six thousand years old in fact. He had discovered that the world had been created on the 23^rd of October 4004 BC. At lunchtime.

This was a pretty momentous conclusion. Not only had Ussher calculated the age of our world to a superhuman degree of precision, he was also lending credence to the idea that the Earth had a beginning (many cultures believed the Earth has always existed, and always will) and that it was pretty damn old, 6,000 years-worth of old.

Today, most people are comfortable with the idea that the Earth hasn’t existed in perpetuity, and most people are OK with the fact that the Earth is billions of years old. But this is a pretty recent mindset. Up until about one hundred years ago, no one really had any idea how old the Earth was.

Here’s what happened…

Goldilocks, and other Habitable Zones for Life

Heard of the Goldilocks zone?

It’s the idea that an area of space around a star will be at the right temperature for life to exist. Not too hot, not too cold, hence Goldilocks.

It’s a bit like standing around a campfire on a very cold night. Stand too far away and you freeze, stand too close and you catch on fire and burn to death.

It’s the same with planets orbiting stars too, if they’re too far away then water freezes and life can’t emerge, and if they orbit too close the planet is roasting hot and nothing can live.

It gets a bit more complex than this though, but complex in a fun way. Oh and its also got some pretty big implications for the search for extraterrestrial life…

Life in our Solar System – Mars

In this series of posts I’ve looked at planetary bodies in our Solar System that could support life, from the moons of Saturn and Jupiter, to the cloud layers of Jupiter itself, to the ephemeral-once-jungles of Venus, I’ve even looked at Earth itself.

Now one of my favourites, Mars, the Red Planet.

What is the Universe?

I’ve been a bit scared about doing this post, but thought I should, as I’ve done posts already on what a solar system is, and what galaxies are, and the Universe is next up in the cosmic scale, so it was only a matter of time until the nagging-voice from somewhere in my brain advocating ascetic completeness won the day and I sat down to do this.

I’ve been a bit scared because it’s a pretty big question, what is the Universe? And I’m primarily a student of geology and biology, so who am I to answer such a question? I’ll give it a stab though…

Life in our Solar System – Earth

In previous posts I’ve looked at some likely, and some less likely, candidates for planets or moons in our solar system that could harbour life, including Jupiter, three of it’s moons, two of Saturn’s moons, and Mars and Venus.

Now its time for Earth. Yep, you read right.

In 1990 NASA used the Galileo spacecraft to look for life on Earth. Why bother you scream, whilst hurling your cup of tea violently against the wall? Well, NASA did it to test how well spacecraft like Galileo can find life on planets and moons from space. Call it a proof of concept, if NASA can find life on Earth, then at least they know the tech works, and hopefully won’t miss signs of life on other planets.

Here’s what they found on Earth:

Life in our Solar System – Venus

In previous posts I’ve looked at the possibility that alien life could be found in our solar system, on three of Jupiter’s moons, in Jupiter itself, and on two of Saturn’s moons.

This time we’re moving nearer to home, to the planet closest to our own, Venus, the second rock from the Sun.

What is a Galaxy (& what is the Milky Way)?

Most people are familiar with the words solar system, galaxy, Milky Way and Universe, and most people probably have a vague idea of what they mean. I’ve been throwing these words around quite a bit on the blog but I realized I’ve never actually explained what they are.

I thought I had a pretty good understanding of what they actually mean, but in an earlier post I defined what a solar system is, and I learnt a fair bit myself about where a solar system actually ends. The same goes with this post, I knew roughly what a galaxy is, turns out I didn’t really know about galaxy superclusters.

So in this post I’ll be talking about galaxies, clusters of galaxies, and I’ll explain what the Milky Way has to do with all of this.

What is a Solar System?

I’ve previously mentioned concepts like the Solar System, galaxies and the Universe, but I’ve never properly explained what each of them actually is. I’m sure most people have a vague idea, but probably aren’t 100% sure.

Read on and I’ll explain what a solar system is. Pretty sure you already know? You may be surprised.

Then in future posts I’ll tackle what a galaxy and the Milky Way actually is, and then what the Universe is.

Actually, for the Universe I’ll try my best, but it turns out the Universe is probably a much weirder place than people previously thought.

The Open University, a different way to study.

OK, this post is going to be an unabashed advertisement for the Open University. I don’t work for them, I’m not doing this for any personal gain, I’m doing it because I’m a student at the OU (I’m working towards a degree in Geosciences), I love it, and I’d like more people to know about it.

If you’ve ever wanted to earn a degree, or just want to study a subject you found interesting, but feel that you can’t attend a traditional university for some reason, be it not enough time or money, or you haven’t got great qualifications from school, or you’re getting on-a-bit and you can’t face all those over-excited teenagers, then the OU may have something for you.