How long would humans survive without the sun?

If the sun vanished, life on Earth would quickly become impossible.

The first thing we would notice is that the sky would go dark. The last rays of sunlight would reach Earth about eight minutes after the sun’s disappearance, as that is how long it takes for light to travel from the sun to Earth. After that, we would only see the faint light of stars and planets.

The second thing we would notice is that the temperature would drop rapidly. Without the sun’s heat, Earth would lose its warmth by radiating it into space. Within a week, the average global surface temperature would fall below freezing. Within a year, it would plummet to -100 degrees Celsius (-148 degrees Fahrenheit). The oceans would freeze over, except for some pockets of liquid water near geothermal vents.

The third thing we would notice is that plants and animals would die off. Without sunlight, photosynthesis would stop, and plants would wither and decompose. Animals that depend on plants for food would starve, and so would animals that depend on those animals. Only some microorganisms that live deep underground or in the oceans could survive by using chemical energy.

The fourth thing we would notice is that Earth would drift away from its orbit. Without the sun’s gravity, Earth would fly off in a straight line into space. It would encounter other planets and asteroids that could collide with it or alter its course. Eventually, Earth would either be swallowed by a black hole or wander into the cold and dark depths of interstellar space.

Some humans might be able to survive for a while by using artificial sources of heat, light, and food, such as nuclear reactors, geothermal plants, or hydroponic farms. However, these resources would be limited and difficult to maintain. Moreover, humans would face other challenges such as psychological stress, social unrest, and cosmic radiation.

Therefore, it is safe to say that humans could not survive without the sun for more than a few years at most.