Intro: What are the most interesting ideas in astronomy for a non-scientist? A few ideas you can carry with you. The ideas that will change the way you look at the world, or maybe your life, or just enjoy them. These are my selection.

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** Speed of light:** light moves at the speed of 300,000 km/s in vacuum. Basically a particle/packet/wave -whatever it is- can travel 7.5 times around the earth in one second. So what?

This has very very serious consequences. Although light travels fast, stars are very far away from each other, thus everything we see is the light we receive now. This light has traveled a long way. This means we can’t see what is happening at this moment. Looking at a star 10 light years away from us, means we are getting lights that have been traveling for 10 years. So we see this star as it was 10 years ago. A galaxy at 65 million light years away? Yes, we see this galaxy as it was 65 million years ago.

If we look at 12 billion light years away, we see 12 billion years ago. What happened around that time you might ask. It was early galaxy formation, thus we see early galaxies. Our universe was born about 13.7 billion years ago. What do we see if we look at that distance?

** It was only hydrogen and helium in the beginning:** Every element we see around us- other than hydrogen and helium-, was made inside stars. The universe doesn’t make heavy elements through the Big Bang, and no other place in the universe has enough temperature for the elements build up, other than stars. We are star dusts!

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