I have a friend who teaches a grade six class. Yesterday she began explaining how the moonlight is really just light reflected from the sun, when the whole class erupted into a volcano of curiosity. She couldn’t keep up with all the great questions they were asking, and had them write them all down. She shared some of them with me, and I thought I’d take a stab at answering them.
“What are planets for?”
Well… planets aren’t really for anything at all. They have no purpose. No particular reason for floating around space. When we look at the barren desert of Mars, or the thick clouds of Venus it’s easy to consider our lovely little earth to be a paradise. I think it’s important to realize that there is nothing special about earth. It formed out of chaos and clouds of dust just as randomly as any other planet in our system.
As for why earth has such a lush ecosystem compared to Mars’ red dust… I suppose it’s a bit like baking a cake. When the ingredients are mixed just right, the cake will rise up light and fluffy. If the recipe is too far off, you end up with a dried out lump of floury gunk. If you were mixing cake ingredients in the same crazy way that the planets were formed, throwing them all around and seeing which bowls they landed in, you’d end up with way more lumps of gunk than you would delicious cakes. It doesn’t make that one cake special… it just happened to work out alright.
“How big exactly was the big bang if it is not a theory and it is real?”
The first thing to talk about here is what scientists mean when they call something a “theory”. Sir Isaac Newton discovered his “Theory of Gravity”, but if you drop a rock on your toe it sure does feel real! A theory is another way of saying “I’m pretty sure I know how this works”. Scientists always like to say they are “pretty sure” instead of saying “I absolutely 100% know this is true”. The reason they do that is because other scientists will always be discovering new things that might change our understanding of something. There is always room for improvement and refinement in science.
When it comes to the Big Bang, it’s always been a challenge for astronomers to see what happened so long ago… 13.7 billion years back! It’s a bit like trying to do a jigsaw puzzle when all the pieces have been hidden all over your city. First you have to find the pieces, then you need to fit them together… and all the while you don’t know what the puzzle is supposed to look like!
Now back to the question… how big was the Big Bang? Well, I suppose you could say it was the biggest thing ever. Everything everywhere… planets, stars, galaxies… was all compressed into one little ball and then it exploded. It exploded so big it spread all the pieces (including you and me) all over the universe, which is almost too big to even imagine. It had more energy than our sun and all the stars in the sky. HUGE energy! ALL energy at once!
“Big” doesn’t even begin to explain it.
“How did people get on Earth?”
This is a bit like asking how you got to the town in which you were born. You never really moved there. You just started there from your beginning. Maybe your parents moved to that town from somewhere else. Or maybe it was your grandparents that first arrived. To find out how humans got here we need to go way back. Way way back. All the way back to that Big Bang thing.
You see, you and I are made up of tiny parts, atoms, just like everything else. At one point all these atoms were part of that Big Bang. Hydrogen and helium atoms were thrown across the universe, and they started combining and mixing into more complex things like carbon and oxygen. If we fast forward about 10 billion years, the cloud of dust, made up of those same original atoms, begins forming into the ball we lovingly call Earth. Fast forward another 2 billion years and some of those atoms just so happened to “bake a cake” and rise up as the first single-celled organisms. A living thing on an otherwise dead rocky planet.
Jump ahead 4 billion years and those single cells have fought and clawed their way (or, at least once they grew claws) to grow into animals and plants. It’s always just a new way of arranging those atoms. Some of those animals became dinosaurs about 300 million years ago. Other animals became mammals somewhat like a mole. Those mammals kept adapting and changing over the millions of years until about 25 thousand years ago our ancestors popped up in the mix. Those early humans kept on growing, becoming smarter and stronger, until… well… here we are.
So we never got here. The stuff that we’re made of has always been here.
Stay tuned for more great questions next time.