Seeing in Infrared

I’ve been doing some research on different types of vision, and apparently what we humans see is the visible wavelength of light – i.e. the colours you see in a rainbow. But many animals, and especially insects, see things we can’t. For example, the humble goldfish can see in both infrared and ultraviolet wavelengths.

Without getting too technical, think of wavelengths as a line of spaghetti of different lengths, from shortest to longest. The shortest bits are in the ultraviolet wavelength. The longest bits are in the infrared wavelength, and there in the middle are the colours we humans can see. Blue is longer than ultraviolet and red is shorter than infrared.

For the purposes of my research, infrared was what I was looking for, but what is it, and what does it look like?

We can’t see infrared, not with the naked eye, but we can feel it because infrared is basically the wavelength of ‘heat’. In visual terms, the colder something is, the darker it appears. The hotter something is, the brighter it looks.

Confused? Good, so was I. As a visual creature, I needed to be able to visualise something that is essentially, invisible. Luckily, we have developed special cameras that can:

  • detect infrared wavelengths, and
  • translate them into colours on the visible spectrum – i.e. into colours we can see.

Generally speaking, infrared cameras translate cold images into dark colours such as dark blue or dark purple. As areas of an image warm up, the heat is translated into brighter colours – from red to orange to yellow to white.

In the screenshot below, the infrared camera shows a cold frying pan on a stove top [the yellow labels are mine]:

To get an idea of what the camera sees as the pan heats up, please have a look at this short video on the National Geographic website:

It’s only a very short video [1.18 minutes] and well worth the look [if you have a phobia about mosquitoes, avert your eyes for the first twenty seconds or so]. Isn’t that amazing?

More on why I’m doing this research at a later date. 😀




About acflory

I am the kind of person who always has to know why things are the way they are so my interests range from genetics and biology to politics and what makes people tick. For fun I play online mmorpgs, read, listen to a music, dance when I get the chance and landscape my rather large block. Work is writing. When a story I am working on is going well I'm on cloud nine. On bad days I go out and dig big holes... View all posts by acflory

11 responses to “Seeing in Infrared

  • Sapling

    This is a topic I think about sometimes. “Visible Spectrum” is merely what we call what is visible to us. It falls on a tiny sliver of the Electromagnetic Spectrum ( Indeed even ultraviolet and infra red are just tiny brackets on either side of our visible spectrum. The actual EM spectrum extends far below infra red all the way down to radio waves, and above ultraviolet up to gamma rays. So I wondered, why did we evolve to zero in on this narrow band? Why not pick another narrow band somewhere else on the spectrum?

    So I started to think, what is a color that if seen, would confer a strong benefit? All I could think of was… Green: The range of the visible spectrum that chlorophyll reflects (isn’t used in photosynthesis). If an animal evolved the ability to see green, it could use it to find plants – either to eat, or to find pray that eats plants.

    So, I took a look at the rainbow and there it was, dead in the middle of the visible spectrum: Green. I doubt this is a coincidence. Not scientific, just a guess, really. but if I were a scientist with time on my hands, I would _look_ into it :).


    • acflory

      I’m…stunned. That makes so much sense to me too. Seems obvious now that you point it out. Every living thing evolves to survive in its own environment. We live on a water world where land based plants use chlorophyll. And they came first. Makes sense that we’d evolve to suit our environment!
      Thank you. I could literally feel the gears in my brain moving to a different position. Small paradigm shift, but a shift nonetheless.
      Just wow. 😀

      Liked by 1 person

  • anne54

    I can always rely on you Meeks to be investigating something interesting! Do you remember those thermal activated T-shirts that were the rage quite a few years ago? They would change colour with the heat of your body. A very short lived fad….maybe they were too attractive to mosquitos. 😀


  • Widdershins

    I suspect it might have something to do with certain creatures of your … acquaintance. 😀

    Liked by 1 person

  • flawedman

    I’m pretty sure you’ve heard of Isaac Asimov , he wrote about 500 books , some non- fiction explaining science of all types.
    One remarkable thing science has done is extend our senses way beyond those developed for our survival by natural selection. We can hear bats , see red blood cells , turn radio waves into sound but ultimately it comes through those five original senses. Our ancestors knew what sort of world they lived in now we are not so sure , physicists scratch their heads , philosophers tax their brains , sensible men and women shrug their shoulders and get on with life.
    The simple magnifying glass led to the microscope and the telescope and now we have Hubble floating out there sending back all manner of stuff that makes us gasp.
    ‘ You are old Father William , the young man said,
    And your hair has become very white;
    And yet you incessantly stand on your head
    Do you think at your age it is right ?

    In my youth Father William replied to his son,
    I feared it might injure the brain ;
    But , now that I’m perfectly sure I have none ,
    Why , I do it again and again.’


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