[thedoc (OP)]

What happens to the photons of light that penetrate the oceans, in fact what happens to the photons of light that hit the earth?

If photons have mass, then is the earth increasing in mass from these photons from the sun and is the sun losing mass from expelling the photons?

If this is the case the Earth's gravity would be getting greater and the Sun's gravity will be reducing.

John Scott.

Asked by John Scott


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John Scott  asked the Naked Scientists:
   An advert on telly about skin protection stating that light can penetrate through thirty meters of water, so what can it do to your skin triggered a thought in me.

What happens to the photons of light that penetrate the oceans, in fact what happens to the photons of light that hit the earth?

If photons have mass as proven from solar eclipse observations of stars behind the sun, then is the earth increasing in mass from these photons from the sun and is the sun losing mass from expelling the photons?

If this is the case the Earth's gravity would be getting greater and the Sun's gravity will be reducing.

The Sun's gravity will be reducing anyway as it burns hydrogen, at a guess, millions of tonnes per second.

John Scott.

What do you think?

There's plenty of things that make the earth change its mass. solar photons heat the earh up. The heat is reradiated back into space as infrared radiation.

[chris]

Yes, but the Earth is also warming up a bit, so the photons are increasing the mass of the Earth. This is a relatively small difference, however, up against the loss of hydrogen into space from the outer atmosphere.

We calculated the Earth's mass balance sheet last year for More or Less: http://www.bbc.co.uk/news/magazine-16787636

And discussed the topic from a different standpoint on this forum, here: http://www.thenakedscientists.com/forum/index.php?topic=42989.0

Chris

[alancalverd]

Photons certainly deliver momentum, which has dimensions of mass x velocity, but as far as we know the mass of a photon is zero.

However all sorts of other stuff from electrons to car-size chunks of iron, is flying towards us from the sun and the rest of the cosmos.

Whilst there is no shortage of hydrogen on the planet, there is a serious concern about the loss of helium. We've only known about the stuff for around 100 years but it is enormously important in industry and may not be around in affordable quantities for the next century.