Blinded by Science blog 8: Why does the sun move?

Well folks, it was an incredibly stressful month of June and I was unable to complete a blog entry during that time.  For my readers (all 3 or 4 of you), I can only offer my apologies and tell you that it will never happen again.

REUTERS/Aaron Josefczyk

That’s how apologies work, right?

Anyway, in an effort to distract you all from the gaping hole that my lack of updating has caused in your lives, here is another question from my cute godson, G.  He asks, “Why does the sun move?”

Jeez, I cannot seem to get him off of this astronomy kick.  Is it too much to ask for some biology questions, things like, “Why are plants’ leaves green” or “Where do babies come from”?  Uhh . . . okay, you know what?  Let’s stick with astronomy for the time being, otherwise his mom might have a few “choice” words for me.

Well G, to answer your question, the sun does not actually move*.  It is actually the Earth that moves while the sun stays still.  When you asked why the sun doesn’t always shine, I told you that the Earth is really big and spins in space.  This means that the sun will shine on different places on Earth throughout the day.  If you remember, I had you perform a little activity to demonstrate.  Your mom stood behind you in a dark room and shined a flashlight at you.  As you stood in one spot and slowly turned to the left, the flashlight came into view (1).  As you continued to turn, you could soon see the entire flashlight (2).  And finally you would start to see less and less of the flashlight (3).

So because the Earth spins around in space, it seems that the sun is moving through the sky, but really the sun stays still.

*For those of you that aren’t three years old, my statement is not entirely true.

Hopefully this isn’t too obscure of a reference.

The sun does actually move.  It (and the entire solar system) revolves around the center of the Milky Way galaxy.  If an Earth year is the time the Earth takes to make one trip around the sun (365ish days), then a galactic year or cosmic year or whatever you want to call it takes roughly 230 million years.  Think of how few birthdays you would celebrate.