Can Humanity Survive Without the Sun?
All Plants Would Die And, Eventually, All Animals That Rely on Plants for Food — Including Humans — Would Die, Too. While Some Inventive Humans Might Be Able...
All plants would die and, eventually, all animals that rely on plants for food — including humans — would die, too. While some inventive humans might be able to survive on a Sun-less Earth for several days, months, or even years, life without the Sun would eventually prove to be impossible to maintain on Earth.
How long would humans survive without the sun?
The current mean temperature of the Earth's surface is about 300 Kelvin (K). This means in two months the temperature would drop to 150K, and 75K in four months. To compare, the freezing point of water is 273K. So basically it'd get too cold for us humans within just a few weeks.
What would happen if the sun died out?
After the Sun exhausts the hydrogen in its core, it will balloon into a red giant, consuming Venus and Mercury. Earth will become a scorched, lifeless rock — stripped of its atmosphere, its oceans boiled off. ... While the Sun won't become a red giant for another 5 billion years, a lot can happen in that time.