sunrays.

**Cavalier** · November 06, 2007, 06:24 AM

I've heard that it takes 8 minutes for the sunrays(right word) to reach the earth, and my question is, if something would hinder the sunrays for some seconds, or perhaps minutes, what would happen to us on earth?

**Juvenal** · November 06, 2007, 06:57 AM

It would get dark...for a bit.

The speed of light that we commonly refer to is actually the speed of light in a vacuum (approx 300,000 kilometres per second).

It is slower when passing through transparent materials. For example the speed of light through diamond is 124,000 kilometres per second.

So if you place a 150 million kilometre diamond between the Earth and the Sun, then the Sun's light would be interrupted for approx 11.8 minutes.

Unfortunately there are some other factors:

When the diamond is placed, we would receive whatever light had been shining into the other side 20 minutes ago.
Also, something catastrophic would probably happen to the Earth due to the gravitational attraction of a 150 million kilometre diamond before the 11.8 minutes were up.

**Cavalier** · November 06, 2007, 07:03 AM

Thank's for the theory and your response.

However, I thougt it'd get ALOT colder, many would freeze to death and it would be absolutely dark, except for the artificial lights.

Perhaps sciencefictional thoughs?

**Juvenal** · November 06, 2007, 07:24 AM

Light from the Sun is interrupted for up to 4 months at the poles, and up to 16 hours at temperate lattitudes (i.e. night time).

If the Sun were to stop shining or disappear permanently, then the Earth would cool steadily until some equilibrium point determined by the amount of heat conducting out from the core.

It may well be that the atmosphere would freeze and precipitate out in the form of snows. You would get distinct layers because the different atmospheric gasses freeze at different temperatures.

I once read a story that used this as a setting. Survivors had to go outside to collect air with snow-shovels and buckets.

Once the atmosphere is gone, it isn't actually that hard to stay warm provided you have a power source - there is no heat convection through a vacuum. You might even need radiators to get rid of unwanted heat!

**Spurius** · November 06, 2007, 07:56 AM

Originally Posted by Juvenal

Once the atmosphere is gone, it isn't actually that hard to stay warm provided you have a power source - there is no heat convection through a vacuum. You might even need radiators to get rid of unwanted heat!

Small consolation in the face of extinction, I fear. Nothing to breathe, nothing to eat, and all the shops closed.

**Cavalier** · November 06, 2007, 12:01 PM

Could always eat some snow ;P

**Simetrical** · November 06, 2007, 12:16 PM

Originally Posted by Cavalier

Thank's for the theory and your response.

However, I thougt it'd get ALOT colder, many would freeze to death and it would be absolutely dark, except for the artificial lights.

Only if it stopped shining for a long period. If it just stopped shining for a few minutes, it would have practically no effect except confusing a lot of people and maybe disturbing the weather a bit. It would probably (I'm guessing here) take days at least of no sunlight for the temperature to even drop a few degrees. Of course, keep it up for long enough and the Earth's temperature would drop to maybe a few tens of kelvins or lower, below the melting points of nitrogen and oxygen (both in the mid-50 kelvins). Then the air would freeze solid, which would be a real Snowball Earth.

With sufficient preparation some humans could probably survive indefinitely under such conditions. Pretty much the only energy sources would be nuclear power, fossil fuels, and geothermal power, but those could last for a few thousand years or longer, especially with a sharply reduced population (say, cut down that six billion to a few ten thousand or less ― probably what would happen). These could be used, basically, to create an artificial environment, sunlight and all, much akin to that in a spaceship. It's not a very happy picture, and it would take a lot of planning.

But realistically, nothing is going to stop the Sun from burning until it becomes a white dwarf, by which point the Earth will have probably been destroyed somehow anyway. So don't worry about it.

**Medicus** · November 06, 2007, 02:39 PM

Originally Posted by Cavalier

I've heard that it takes 8 minutes for the sunrays(right word) to reach the earth, and my question is, if something would hinder the sunrays for some seconds, or perhaps minutes, what would happen to us on earth?

It would get dark for a bit. It's commonly referred to as an eclipse.