When we look at a blue recycle bin, we see blue

When light hits an object, that object absorbs some light, and reflects other light.  A blue recycle bin absorbs red and green light, but reflects blue light.  The blue light then hits your retina at the back of your eye and a signal is sent to the visual cortex of your brain.  Your brain then perceives this signal as colour.

3.2x10^7

layers of the earth affect the waves and these effects are seen on instruiments such as seimometers