If you’ve ever had even a passing interest in space, then this post is for you.

 

“Space is big. You just won’t believe how vastly, hugely, mind- bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space.– Douglas Adams
I want to tell you a little bit about space.  But first, I’d like to remind you that while you may think you’ve never been to space, you’re wrong – you’re in it now.  Both you, I, all politicians and corporations, all homeless people and people who’ve ever died have lived in space – in this space.  On Earth, as we call it.

 

The thing about the Earth you have to remember is

that it’s old, and heavy.  I’m talking 4.5 Billion with a B years old, and 5.94 X 10^21 tons, comprised mostly of iron, making it the densest planet in the solar system and the largest terrestrial planet.  And it’s got some energy, 2.6 X 10^33 joules in fact.  The Earth is both huge and fast, sixty six thousand miles an hour around the Sun.  That’s the planet we live on, the only known planet to harbor life, which is more a statement of the shortcomings of humanity than of the scarcity of life.

Note:  I can do nothing to help you appreciate the sheer scale of the following objects, but do realize that even if you could travel the speed of light for your entire life from birth to death 120 years later, you wouldn’t get further than a small group of very close stars.  You could only travel to Alpha Centauri around 28 times if you never stopped or slowed down.  Think of how many times you’ve driven to work or how long it took you to take your last vacation around the world and then you’ll get a feel for the incomprehensible distances of the following.

On the Solar System

Our solar system is only slightly older than the earth by about 100 million years.  It’s about 100AU, with that range varying widely as our furthest probe, Voyager 2, has arguably passed the Heliopause multiple times.  Our solar system itself is mostly the Sun, with 99.86% of the mass coming from the Sun itself.  We’ve only explored only a very small part of it, and only sent humans to our nearest satellite, the Moon.

 

On the Galaxy

Our Galaxy is called the Milky Way, an average spiral galaxy. However, the total number of stars in just the Milky way is between 2×10^11 to 4×10^1, something like 200-400 billion stars.  The human mind is not accustomed to the word billion, so let me give you a sense of scale.  If you could visit one star system every second (breaking the speed of light several times over), it would take over six thousand years, about the full extent of recorded history.  Everything you’ve ever done is more recent than the light from nearly every star in the Milky Way.  Just exploring the Galaxy enough to have seen 1% of it will be a feat of several hundreds of orders of magnitude greater than anything humanity has ever done.

On the Universe

It is at best millenia away, but one day humanity might traverse the vast distance between our Milky Way to another galaxy.  Unless humanity matures and the laws of physics go through several major revisions, humanity will most likely be stuck in our own galaxy, but it is not an impossible feat.  The Universe is so gigantically large that there could be millions of civilizations that will never reach each other due simply to scale.  But it’s where we live, and it’s what we’ve got to play with.