# How long would we have?

How long would life forms be able to live if the sun were to just dissapear and send us flying into space?
How fast would the planets temperature drop to a dangerous level?

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Redbelly98
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If I wanted to make a rough estimate, I'd consider how much the temperature usually drops from daytime to nighttime. About 10 C, or 15-20 F? Then imagine the temperature continues dropping by that much every 12 hours.

In just wondering thought. I would think surface life forms would be gone relatively fast (including us). Plant life would also perish due to absence sunlight and cold.

However, if looking at broad spectrum life forms. I would think simple life forms would be around for a long time, perhaps several millions of years.

Sub terrain life forms would still have geothermal heat. Also I don't think the oceans would freeze to the bottom for the same reason. There may be several kilometers of ice but still still liquid H2O under it.

As an example the life that exists around geothermal vent in the deep ocean is quite robust. to both temperature and pressure.
The same thing being with bacteria that exist withing the deeper earth.

I guess the planet would eventually wonder off in the direction of Proxima Centuria.
However, I don't think it would be a totally dead planet for quite a long time.

But, I am not going to worry about the Sun just shutting down on a moments notice.

In just wondering thought. I would think surface life forms would be gone relatively fast (including us). Plant life would also perish due to absence sunlight and cold.

However, if looking at broad spectrum life forms. I would think simple life forms would be around for a long time, perhaps several millions of years.

Sub terrain life forms would still have geothermal heat. Also I don't think the oceans would freeze to the bottom for the same reason. There may be several kilometers of ice but still still liquid H2O under it.

As an example the life that exists around geothermal vent in the deep ocean is quite robust. to both temperature and pressure.
The same thing being with bacteria that exist withing the deeper earth.

I guess the planet would eventually wonder off in the direction of Proxima Centuria.
However, I don't think it would be a totally dead planet for quite a long time.

But, I am not going to worry about the Sun just shutting down on a moments notice.
Obviously gravity would be affected...what would happen to the atmosphere...step by step?

Gravity on the earth per se would not be effected. We would loose the solar gravitational attraction letting us go off is some arbitrary direction.

As the temperature started to drop, the coefficient of volumetric expansion would kick in and start to reduce the volume of atmospheric gases.
The surface pressure would rise slightly. As the temperature falls further each atmospheric gas will arrive at a pressure / temperature curve in which the gas will liquefy.

Ignoring trace gases, oxygen would liquefy depending on the pressure ≈ 180°C. Nitrogen would not be far behind at ≈ 195°C.
Some trace gases would drop much more in temperature before liquefying.

Perhaps there may for a time be enough geothermal heat escaping at the surface to vaporize surface liquid O2 / N only to condense and ‘rain’ back to the surface.

Generally, earth would eventually take on the attributes and become much more like Titan or Europa.

I think Redbelly's estimate is probably good. If we start at 80F or 300K, and figure a 10K per 12 hour drop that's about 6.6% drop per day, giving 44F after one day, 10F after two, -20F after three, -51F after four. I don't know how you want to define a dangerous level, but I'd guess almost all humans would be dead within a week.

I wonder who would be best off for living the longest. At first the ISS popped into my head, but without the sun for solar power they wouldn't last long. Next I thought about a nuclear sub. They can go months without surfacing, and the ocean would probably retain heat for a while. If they set down on the floor somewhere where it isn't that deep and get as much geothermal heat as possible. I'd guess they'd last a few months until their food ran out. Scientist at the Antarctic research station would be somewhat prepared but as Waveform pointed out oxygen in the air would become liquid, so even if they could keep warm breathing would be the real issue. I can't think of any human that would be able to survive more than a year.