What happens to the photons?

[Stargazer51N]

I don't know why, but this morning I suddenly thought to myself ...

What happens to the light from celestial objects once I have observed it? Do the photons pass straight through the back of my eye and out through my head, do they get absorbed by my eye or does something else happen to them?

A strange thought to just pop into my mind, I know, but I'm hoping somebody can put me out of my misery and tell me what happens.

[Asur84]

They may bounce around your head and find their way out through your ears lol, on a serious note though I think they are absorbed by the eye.

[Stargazer51N]

They may bounce around your head and find their way out through your ears lol, on a serious note though I think they are absorbed by the eye.

That now leads me to wonder ....

If the photons are absorbed by the eye does the energy get dissipated as heat?

Don't know why these questions keep popping up. Watching the Brian Cox A Night With The Stars and trying to understand quantum physics must have stirred some of the old grey cells

[cantab]

A related thought I had the other night when I was watching for Quadrantids, was that just as I'm seeing photons that have travelled dozens or hundreds of light-years from the distant stars, so as I'm looking up the heat radiating off my face is travelling outwards, and maybe one day those photons will pass by the star I'm looking at.

I've yet to calculate just how many photons per time period would do so.

[Captain Caveman]

Photons are small packages of energy (quanta) which are emitted during an energy releasing activity (eg fusion) They are then absorbed by light sensing cells which will then excite electrons in a pigment on your retina which will then cause the nerve cell to fire to your brain

When the electron falls back down to a lower energy level they will emit energy in a different energy form

Or something like that - quite a while since my physica A-level!

[Adrian]

The photon's energy will be lost in the background heat of the body like starlight in the daytime.

The energy in photons is negligible in comparison to the energy being produced by the body**. The cells in the retina have evolved to react to this minimal energy in photons in a particular energy (wavelength) range, but the effect is like an electrical relay or amplifier - a small trigger energy creates a large signal powered by the chemical reactions in our cells.

**Direct sunlight over the surface of our body has a noticeable effect as warmth, however, the retina shouldn't receive direct sunlight!

[Stargazer51N]

Thanks for putting my mind out of it's misery everyone - some very interesting answers.