Eight planets (As Pluto is not lucky enough to be considered as a planet anymore) and their moons, tens of thousands of asteroids revolve around the sun. One of these is our Earth, orbiting the sun at an average distance of about 92,960,000 miles (149,600,000 kilometers). The sun is a huge, glowing ball that provides light, heat, and other energy to our Earth. Sun is already doing its thing for almost 4.5 Billion Years. So how many years is left before the sun dies? According to NASA almost 4.5 billion.
So What if our Sun dies?
If you put a steamy cup of coffee in the refrigerator, it wouldn’t immediately turn cold. Likewise if the Sun turns off, which is physically impossible, Earth will still stay warm for millions of years. But not at its surface.
In a year its surface temperature would dip to –100° F. The top layers of the oceans would freeze. But that ice would insulate the deep water below and prevent the oceans from freezing solid for hundreds of thousands of years. Millions of years after that, our planet would reach a stable –400°, said David Stevenson, a professor of planetary science at the California Institute of Technology.
Only some microorganisms living in the Earth’s crust would survive but most of the life will end soon after the Sun going dark. Most of the plants would die in few weeks as photosynthesis would halt immediately. So all the food chain depending upon greens will die and same will happen to others.
Humans could live in submarines in the deepest and warmest parts of the ocean or there might be nuclear- or geothermal-powered habitats, where people could continue harnessing volcanic heat for hundreds of years. But these are all the theories.
The sun doesn’t merely heat the Earth; it also keeps the planet in orbit. If its mass suddenly disappeared (this is equally impossible, by the way), our planet would fly off from its orbit.