Most vertebrates have eyelids or some other means of protecting their eyes from strong sunlight, which would otherwise cause irreversible damage. Insects, and many other invertebrates, on the other hand, habitually sit or cruise around with their eyes, or parts of them, pointing upwards towards full sunlight, with no apparent adverse effects. Why does direct sunlight not damage their eyes?

As a supplementary, would photographic flash light damage the eyes of an invertebrate?

If we consider thermodynamics and its law that heat travels from hot to cold, I was curious as to how or what occurs when sunlight is travelling to Earth. The gap between the Sun and the Earth is effectively a vacuum and also the low pressure at high altitudes mean that it is very cold, surely the heat should be dispersed by then and not reach sea level.

I would like to know how we still manage to feel the heat.

Thank you

This photo was taken on a train travelling south to Hastings. The flat windows had horizontal and vertical scratches, perhaps from cleaning. The arc that is illuminated by the sun appears to be centred on the vanishing point of the axis of the carriage. The Sun lies on the arc. Why this arc?

I work in and underground mine here in Australia.  One of my co-workers sneezes whenever he drives out of the entrance to the mine.  Shortly after we travel from the darkness of the underground mine and into bright sunlight.  He's been here for 22 years and says that it happens every time.  Why?

Whenever you see the Starship Enterprise off on a mission, an 'outside' shot always shows the vessel in full visiblity - but how visible would it be? must you always be illuminated by lights on the top, or a planet nearby? If we were away from any planets and suns, and I were to space walk a few hundred yards away from the ship, and it had no lights on the outside, would I only see stars and a black 'shadow' where the ship was? Or is there always residual light? could I for example see my own hand in front of my face? or is there a point where you can see nothing nearby, but only stars and galaxies in the distance?

Obviously we can all see full spectrum light when it's pointed directly at us or when it's reflected/refracted off of an object. However if a light (a torch say) was shined horizontally across our field of vision, from an angle where we could not observe the light directly. Across a vaccum where the beam of light would not be interfered with or interrupted whatsoever. Would we be able to observe the beam of light. If so, how? And if so, wouldn't space be light instead of black?

I've just been looking at some of the pictures voyager took of Uranus and Neptune. If I'd gone along for the ride would I have been able to enjoy the view with my unaided eyes, or is it quite gloomy so far from the sun? Could I read my newspaper on Pluto?

As an amateur photographer I'm familiar with the idea of light having a colour temperature and having to adjust a camera for white balance e.g. early morning light is much warmer than midday. I've read in books on photography that light before dawn is always colder than the light after sunset.  I would have expected it to be the same.  Why should the direction of the light affect its temperature? Is this just a UK phenomenon or is it worldwide ?

Quite often, but not always, when stepping out into bright sunlight I sneeze a couple of times. That's probably it for the day, I am most unlikely to repeat the sneezing when going out again later. Why does it happen and what causes this reaction ?