The Meaning of the “Speed of Light” and “Light-years”

How do we know what the universe looked like 5 billion years ago?  We look back 5 billion light years!

But what does this mean?

The speed of light is ___________________and has the symbol ____. 

 Since speed means ________divided by _______ or in equation form ____ = ____/____.

In one second light will travel _______________meters which is _______million meters.

That’s difficult to picture, so let’s use the size of a person for scale.
If we put people standing side by side how many people would that be?      
 
I would approximate the height of a person to be _____m.

How many people fit into 300,000,000m standing on each other’s heads? (Show your work.)         

Since there are over 6 billion people on Earth, if we stood on each other’s heads, how long would it take light from the bottom person’s big toe to reach the top person’s head? (Show your work.)

So light travels really, really, fast.  But how does this relate to the Earth, the Solar System, a galaxy, or the Universe?
The Earth’ diameter is 12.8 million meters     (1.28 x 10^7 m) 
How many Earth’s side by side would cover the distance light travels in 1 second? (Show your work.)

       

How many Earth’s side by side would it take to cover the distance light travels in 1 minute?  (Remember 1 minute = ______seconds.) (Show your work.)

How many times will light travel around the Earth (think circumference) in 1 minute.  (Remember Circumference =_______________.) (Show your work.)

So, now you have a sense of how far light travels in a minute. But what about a light-year?

How far does light travel in 1 hour?  (Hint start with the speed of light in m/sec and convert it into m/min and then m/hour.) (Show your work.)

In one day?

In one year?

 One light year is _____________meters and in my own words a light year means:

 We can see over 14 billion light years of the universe, in my own words that means:  

      

Now, pick another object in the universe and make up a problem relating it to the speed of light.  Be prepared to share this with the class.