Our Earth is a pretty big place, enough to explore for a lifetime. The solar system is even larger, including eight whole planets. Yet, all of these things pale in comparison to the Universe. The Universe is the sum of everything in existence – life, planets, stars, and anything else you can imagine!
A wide view of space. This isn’t the whole Universe (not even close). But, we can’t just take a picture of it! We’re still stuck in the Solar System.
When we say the Universe includes ‘everything,’ we really mean it! But, we might not fully appreciate what that includes.
Everything is all matter (or material that takes up space). Better yet, it includes space itself. ‘Space’ was actually created when the Universe was. Incredibly, so was time! Something so basic as time itself is part of the Universe. And if that’s the case, what’s not?
If time is part of the Universe, is checking your watch considered astronomy?
Now, all of this Universal stuff is a lot to keep track of! We have to make sense of it somehow. So, let’s briefly put it in order.
Structure of the Universe from Earth
Zooming in: Welcome back to planet earth. Our earth is a medium-sized planet in a system of planets surrounding a central star. This star is the sun. And, as big as the sun is, it’s also orbiting something.
It’s part of what we call a galaxy, or a large group of stars. All of the stars in this galaxy are orbiting a HUGE black hole. But guess what? Our galaxy is only one of hundreds of billions of galaxies.
A drawing of a galaxy. The stars in it are as tiny as ants.
Lots of these galaxies make-up what we call a supercluster. Finally, several superclusters form the largest things in existence: galaxy filaments. These are huge, bright strings of galaxies. They’re like Christmas lights, decorating a Universal tree.
Finally, we’re finished! That’s, well, everything…Okay, actually there’s more. All of the things we just described are only part of the universe. NOT the Universe.
Wait, what’s the difference?
Universe vs. universe
Capitalization is key! There’s actually a major difference between the U-niverse and the u-niverse. It’s a simple one, but still significant.
The u-niverse is the smaller of the two. It’s the part of the U-niverse that we can actually see. Visible light is a part of the Universe, but it’s only in a subsection of it. This luminous zone is the u-niverse.
Oppositely, as we’ve said before, the U-niverse includes literally everything (even the things we can’t see).
How Big is the Universe?
The answer: scientists aren’t sure. They’ve only estimated the size of the u-niverse, but even that is astounding. It’s 91 billion light-years wide! We can’t even imagine how big that is.
Still, people want to know the size of the bigger Universe. Unfortunately, we have no clue. The main problem we run into is, again, just not being able to see what’s out there. Light just hasn’t reached that far into space yet. As it travels, we get a clearer picture of space as a whole.
Light beams traveling in space. What will they reveal next?
Maybe one day, the light will hit an edge and stop. That would tell us the size of the Universe. Conversely, the light could go on forever! Unless something happens to it, we can only really guess.
How Old is the Universe?
Luckily, we have a better answer to this question. The age of the universe is 13.8 billion years! This is really an amazing fact when we put it into perspective. Human beings rarely live more than 100 years. Doing some math leads us to the following conclusion:
Our lives are a smaller part of the age of the universe than a second is within a year. Let’s say this another way. If the Universe was a year old, we would live less than a second.
And how was it born? That’s a whole other story. There’s time enough in the Universe to tell it, but not in this short article!