My 30 month old son asked me why people's eyes will hurt if one stares at Mr Sun. I told him the sun shoots sunlight, which is not visible and not touchable. But it exists and is made of atoms just like other things we can see. If it hits our eyes, our eyes will hurt just like a man hurts from a car accident.

But it is not convincing answer, and I wonder if there is an easy way to explain this phenomenon to him?

  • 8
    Please use comments appropriately: do not answer in comments and do not start side conversations (or post jokes). That includes discussing how the physics of the explanation are wrong -- we're Parenting.SE, so keep details like that in an answer (if it will be helpful for a parent to say to a child).
    – Acire
    Commented Feb 9, 2016 at 13:34
  • 280
    @Erica Was the "answer from @user20775" (as mentioned in the accepted answer and one other answer) among the comments you deleted? If so, it seems you've removed useful information; moving it to a chat instead would have at least preserved it temporarily, and turning it into an answer would have been even better. Also, saying that sunlight is made of "atoms" is (in my opinion) an egregious enough mistake that it seems worth keeping in comments here (since on its own it's not an answer to the question as asked). And yes, it is helpful for parents not to teach children false physics. Commented Feb 13, 2016 at 0:43
  • 1
    No, it wasn't a comment, it was an answer; a user changed their username. I'll edit the relevant answers so it's more clear. Also, while I agree that parents shouldn't be teaching inaccurate physics, the details of how light works are beyond the scope of Parenting.
    – Acire
    Commented Feb 13, 2016 at 0:48
  • 2
    Why would you make reference to a car accident? I certainly hope the child doesn't know what a car accident feels like. Commented Feb 17, 2016 at 13:46

12 Answers 12


I like the answer which discusses a sunburn.

To get a more visceral reaction, you could show him how a magnifying glass can burn things by "bunching up" (focusing) the sunlight. That should show him that the sunlight really is a destructive force.

  • 2
    Or show him what a fresnel lens can do. youtube.com/watch?v=GcL7s9aX494
    – Daniel
    Commented Feb 9, 2016 at 14:13
  • 11
    Add that there's a lens at the front of the eye that works in the same way. Commented Feb 9, 2016 at 15:15
  • 2
    I think the magnifying glass is an excellent practical example.
    – Joe
    Commented Feb 9, 2016 at 16:57
  • 25
    I'm not sure you want to teach a 30-month-old how to easily burn things. It could have serious consequences.
    – yo'
    Commented Feb 9, 2016 at 21:07
  • 2
    I have no 30 month old (yet!), but if one is worried about teaching a 30 month old how easily you burn things, one solution might be to instead focus it well on the ground, and permit the 30 month old to put their own hand near the focal point and feel the pain. It strikes me that, if done voluntarially, he may not associate the pain with you, and a magnifier is not a very effective tool for inflicting pain on others (who move). The message, after all, is that it will hurt him if he looks at the sun with his eyes. Permitting him to simulate it might work.
    – Cort Ammon
    Commented Feb 12, 2016 at 1:51

My answer for a four year old girl:

"You know how your skin gets burnt in the sun? You know your eye is very soft? The inside is even softer and gets burnt very quickly. Pretty much straight away."

  • I edited for clarity - if that's not what you meant by the first sentence please clarify.
    – Joe
    Commented Feb 9, 2016 at 16:56
  • 4
    And - I think this is by far the best combination of accuracy and age-appropriateness.
    – Joe
    Commented Feb 9, 2016 at 16:56
  • That's what I meant. Sorry first post and still getting used to the preferred styles here
    – NilbogAus
    Commented Feb 9, 2016 at 19:54
  • 1
    Is it sure to assume one will know in that age how sun may get burned by sunlight? Is this something a 2.5 yo is safe to be assumed to have experienced? I'm just curious.
    – Zaibis
    Commented Feb 11, 2016 at 13:53
  • 1
    My five year old has never had a sunburn. We don't let her go out in intense sun without sunscreen. Sure she knows we have to wear sunscreen to protect our skin, but not having experienced a sunburn, I don't think she'd have the same appreciation.
    – corsiKa
    Commented Feb 12, 2016 at 18:24

Tell him the truth, no weird contradictions. Mr Sun does not shoot something invisible, because obviously you can see light. Furthermore, it is not made of atoms (at least not in physical sense, of course, in some philosophical sense, it is).

Just mention that the Sun emits very very much light, and too much light hurts.

This is the way it is, although it answers his question by his premise. From a philosophical point of view, this is an answer he has to accept with no further explanations (like a dogma or an axiom).

This is the bare truth, not too much information, and every child is smart enough to cope with it.

  • I like this answer the best, but mentioning the "softness" as another answer put it (I'd probably try and convey the meaning of "delicate" or "sensitive"). This could (with caution) be demonstrated with the use of a torch or other bright light source and then adding the sun is much brighter again (by many orders of orders of magnitude) :)
    – Madivad
    Commented Feb 9, 2016 at 12:19
  • 1
    In point of fact light is not visible in itself, otherwise you'd just see light. What vision is made up of is light bouncing off things, as the photons strike our retina and are turned into nerve impulse. Commented Feb 9, 2016 at 15:13
  • 5
    Okay, if photons are part of light or the light itself should be left to scientists and their plurality of theories of light, not to 30 months old children. Commented Feb 9, 2016 at 15:22
  • 4
    @GeoffAtkins when you're watching the sun, the photons we talk about haven't bounced off of anything since they've departed from the Sun 8.3 minutes ago. Commented Feb 10, 2016 at 12:57
  • 9
    @GeoffAtkins "Light is not visible in itself"? Actually, the only thing that we can see is light.
    – Zenadix
    Commented Feb 10, 2016 at 18:18

The answer is not convincing because it is not true. Tell the child the truth: that we can see because our eyes are sensitive to light, like our body is sensitive to touch – and like too much touch (a hit, actually) may cut our skin or break our bone, too much light may burn our eyes' interior.

Atoms or EM radiation are irrelevant now, but it's important to emphasise 'too much light', because one can get too much light form other sources, too. For example one should avoid looking at naked bright light bulbs or into a torch light, and especially into laser pointers.

  • A note about laser pointers: the power output of a laser pointer makes all the difference. Cheap-o $2 laser pointers usually have such a low power output that you could stare unblinking into the beam for hours and never cause permanent damage. Others are so powerful that even scattered reflections entering your eye can damage it immediately.
    – Marsh
    Commented Feb 9, 2016 at 19:36
  • @MartinCarney This is a good point, but for the sake of simplicity (talking to a toddler) I'd still encourage "no laser pointers" :)
    – Acire
    Commented Feb 9, 2016 at 20:36
  • @Erica Oh, absolutely! I just recall my father chewing me out as a teen (ie perfectly capable of understanding the nuances of laser power) for pointing a laser pointer at my webcam because he thought it would damage it.
    – Marsh
    Commented Feb 10, 2016 at 2:52

Take a bit of toilet paper, and hold it under the bath's faucet. Turn on the faucet just slightly, so there are small drips. See that? The paper holds.

Now turn the faucet on full blast. Does the paper hold up? Nope.

Intensity can be damaging/harmful. An example could be made by making a soft touch with one finger, or allowing a whole hand to fall two inches. Which is more intense and damaging? Likewise, you can make a powerful slap. (Slap your own skin... it won't be child abuse, it likely won't hurt, but it is likely to be loud.) Explain that intensity is damaging.

Explain that it is not just the sun that can damage eyes, but sufficiently bright light. Also explain that the sun is very intense light.

Explain that looking at the sun for two or three seconds is probably not going to be a major danger. But looking at it for longer can cause problems. Analogies can be touching something somewhat-hot, or some other stimulus that just gets annoying/painful/undesirable when sufficiently repeated.

  • 1
    This is great if you want a bathroom full of soggy toilet paper the minute you go downstairs.
    – corsiKa
    Commented Feb 12, 2016 at 18:22
  • 2
    Which will then make a good question.
    – gnasher729
    Commented Feb 13, 2016 at 12:38

Like other respondents, I think you should tell your son that the inside of your eyes can burn, just the same as your skin can, but quicker.

But because your skin is on the outside of your body, it has lots of pain sensors to detect when things could damage it. The inside of your eyes don't have pain sensors because they're inside your body where they don't get touched by damaging things. That means that when you damage your eyes, you won't feel it, which is why you need to be extra careful.


Use it as an opportunity to teach moderation.

Your child probably knows that being warm feels nice, but too much warmth can be uncomfortable, and even more can burn. A cool breeze is nice too, but too much and we get cold, and can even get hurt.

It's the same with light from the Sun, we like having enough so we can see, but too much and it can hurt us.

This can be used in similar lessons about other things that are nice in moderation, like candy, food, and a whole lot of other things they won't know about until adulthood.


Great methods are by showing it in a practical manner. Showing how a magnifying glass can harness the sun's power, or you can explain how everything we look at is reflecting light from the sun, and thus has been weakened in strength and doesn't hurt our eyes. But say you take a mirror which reflects almost all the light, that will hurt our eyes.

After you show these things, you can explain the seriousness of the matter, that our eyes are very sensitive to light so that we can see all this reflected light, but are way too sensitive for direct light, etc. And just as we get sunburned on our skin that acts as a shield, our eyes are not a shield and directly get damaged permanently.

Some other people said using it as an exercise of moderation. I agree with that totally and think that would be very effective.


Take a black piece of wood (or something similar, black metal will also do) outside with your son. Then stay for a short time in the sun. Let him touch the piece of wood (be careful if using metal, this can get too hot to touch). It should have gotten really warm. Now let your son look in a mirror and ask him what color his pupils have. Now he should have learnt that dark colored things will get very warm in the sun and this may be harmful.

  • Except that your eyes aren't dark coloured. The dominant colour of your retina is red, from the blood. The pupils look dark, because they're a window to a room with very little light, basically. That's what causes the "red eye" effect when using a flash camera - suddenly, a lot more light hits your retina and reflects (well, diffuses) back out, resulting in red pupils. The same principle makes sunglasses appear black - and yet you use them for shielding your eyes from the Sun, don't you? :)
    – Luaan
    Commented Feb 11, 2016 at 13:03
  • @Luaan is it really relevant for a 30 month old to know that there is something behind the dark coloured pupil he is able to see in the mirror? The effect is the same whether it is the sun glasses, the wood or the eye - the darker it's color is the hotter it gets in the sun. Commented Feb 11, 2016 at 13:38
  • 1
    But that's the point - the pupil isn't dark. It's just a window, and it lets all the (visible) light through. The reason it appears dark is that very little visible light leaves the eye, compared to how much is "reflected" from the parts around the pupil. It's about contrast, not absolutes. Your eye is perfectly capable of handling the intensity of visible and infrared light it receives when looking directly at the sun on a clear blue sky as long as you don't mess with eye's adaptation (e.g. looking through a pinhole, or during an eclipse). It's the UV light that harms your eye.
    – Luaan
    Commented Feb 11, 2016 at 13:46

point out to your son that the iris of the eye is a lens.

get a magnifying glass.

point out to your son that the magnifying glass is a lens.

take your son out on a sunny day.

use the magnifying glass to focus the sun light onto some flammable material like some paper.

State the obvious that the focal point in the back of the eye will react the same as the paper.



You can give him a similar experience (though not actually damaging) by taking him in to a darkened room.

Wait in there a bit while your eyes adjust.

Then either turn the light on, or go out to a much brighter room.

The discomfort can illustrate your point without damage.

  • I don't think this answers the question, though. That discomfort (the time your pupils take to adjust to the light source) is not actually related to the reason that sunlight burns your eyes, and in fact it's very possible to do significant damage to your eyes without feeling significant discomfort (for example, if you wear sunglasses).
    – Joe
    Commented Feb 12, 2016 at 22:16

The sun is hot. Extremely hot. Hot things can burn. I don't believe you need to make the explanation any more complex than this, or attempt to explain it scientifically.

The answer you've given the child would likely confuse him more.

The analogy to a car accident I believe is not at all appropriate. The child presumably has no experience of car accidents, so would have no way to understand what a car accident would feel like. Speaking from experience, a car accident feels very different to looking at the sun.

If you're going to try to explain the concept of 'hurt'. It would be best to use something the child may have had experience with, grazed knees, ear infections, getting new teeth etc. The child would very likely understand that these are unpleasant sensations, so would want to avoid anything that may be equally unpleasant.

You could therefore say something like "if you look at the sun, your eyes may hurt, like your knee hurts when you fall down."

Also if you want the child to not look at the sun, avoid personalizing it. i.e. stop referring to it as "Mr Sun". The child might be trying to see Mr Sun's smiling face.

  • 2
    This answer could use some work to improve it's tone. For example: "I cannot fathom how you would have thought this an appropriate way to explain" adds pretty much nothing to your own explanation, and serves only to criticize the OP for doing what they thought was best to explain a situation to their child. Be welcoming, be patient, and assume good intentions.
    – Acire
    Commented Feb 18, 2016 at 1:23
  • Thanks @Erica, your suggestion has been noted, and I've changed the wording accordingly. Commented Feb 18, 2016 at 4:11

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .