Week Six: A Bird's Eye View

From satellites, we are able to gain visual information impossible to see with the human eye.  For example, satellites have the capability to capture thermal or ultraviolet images.  Although these parts of the light spectrum are invisible to humans, different animals can perceive them just as clearly as we see color.  In order to better understand the light spectrum beyond what we can see, this week we studied the eyes of birds, an animal that can sense ultraviolet light.  Now if you're like me, the only information you remember about how eyesight works you learned before high school.  Prior to this week in class I basically remembered the basic eye parts like the iris, cornea, and optic nerve, and that at some point the image we see is flipped upside down.  Other than that I was in the dark, so I'll just assume you are too and give a little crash-course on vision.  First, when we see something with our eyes, we are sensing parts of the light spectrum.  On the light spectrum, there are various waves of different lengths.  For each different type of wavelength, there is a coordinating photoreceptor.  In humans, we have rod and cone photoreceptors that pick up certain waves, which allow us to sense different colors (Fairchild, 9).  We don’t have all the types of photoreceptors to see every part of the light spectrum, though, which is why we can’t see in the dark or sense ultraviolet or heat waves.  

 Way back in history, when mammals started to evolve, we lost two of our four cone pigments.  Later on humans did evolve back to having three cone pigments (Goldsmith, 71).  While humans only have 3 types of cones, birds on the other hand use four cone pigments, allowing them to sense in ultraviolet.  This creates a whole different world to sense visually.  

 

The difference of a flower between what we see (left) and what birds see in ultraviolet (right)

Source: http://www.lifepixel.com/galleries/uv-ultraviolet-photography-gallery 

 While the ozone layer filters out much of the ultraviolet radiation coming to Earth, ultraviolet astronomy can only be conducted from space, which makes satellites integral to this type of research (http://www.scienceclarified.com/Ti-Vi/Ultraviolet-Astronomy.html).  With the use of satellites, we have the opportunity to broaden our view of the world beyond what we can see with our sense of vision and truly see from a bird’s perspective.