Fem år gammal ritning
Why is the sky dark at night? You might think the answer is obvious - the sun isn't up! But the only reason the sky looks blue during the day is that sunlight scatters off of the atmosphere -...
It all started with a big bang. Wait, we don't have to go back that far. The earth was formed 4.5 billion years ago. No, still too far. Try this. It's the middle ages. People in...
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