What would happen if the Sun went out?
What would happen if the Sun went out?
Eight minutes and twenty seconds of normality, then permanent night — and surface temperatures below freezing within a week.
Reasoned extrapolation
Light takes about 8 minutes 20 seconds to reach Earth, so that is how long nothing would appear to change. Photosynthesis would stop immediately once darkness arrived, collapsing the base of nearly every food chain within weeks to months. Surface temperatures would fall below 0 °C within about a week and continue downward, reaching perhaps -70 °C within a year as the atmosphere radiated its heat away, eventually cold enough for the atmosphere itself to begin condensing. If the Sun's mass vanished along with its light, Earth would leave its orbit on a straight tangential path, and the change in gravity would arrive at the same moment as the darkness because gravity propagates at the speed of light. Life would not end entirely: deep-ocean ecosystems around hydrothermal vents run on chemistry rather than sunlight, and the ocean beneath a thickening ice cap would stay liquid for a very long time.
What happens, in order
| When | What |
|---|---|
| 8 minutes 20 seconds | Darkness arrives; nothing before this |
| Days | Photosynthesis has stopped; surface temperature falls below freezing within a week |
| Months | Food chains collapse; ocean surface freezes over |
| Years | Surface near -70 °C; deep ocean and vent ecosystems persist under the ice |
How confident this is
This is a reasoned extrapolation rather than an observation. The mechanism is understood, but the scale of the consequences depends on assumptions that could reasonably be argued differently.
The Earth
- What would happen if the Earth stopped spinning? Everything not bolted down would keep moving east at up to 465 metres per second, and the oceans would migrate to the poles.
- What would happen if the Earth lost the Moon? Tides would drop to about a third, nights would be dark, and Earth's axial tilt would eventually wander.
- What would happen if all the ice on Earth melted? Sea level would rise by about 70 metres, redrawing every coastline on the planet.
- What would happen if all the bees died? Serious, expensive and not civilisation-ending — most staple calories come from wind-pollinated grasses.
- What would happen if the Earth's magnetic field flipped? It has flipped hundreds of times already, most recently 780,000 years ago, with no mass extinction attached.
- What would happen if all the trees disappeared? A carbon and water-cycle catastrophe — but not suffocation, because most oxygen production is marine and the atmosphere holds a huge reserve.
- What would happen if the Earth spun twice as fast? A twelve-hour day, more violent weather, and everyone at the equator about 1.4 per cent lighter.
- What would happen if the Moon were closer to Earth? Tides scale as the inverse cube of distance — at half the distance they would be eight times larger.
- What would happen if all the volcanoes erupted at once? Sulphate aerosols would cool the planet for years, then the released carbon dioxide would warm it for millennia.
- What would happen if the ocean currents stopped? North-west Europe would cool sharply while the tropics warmed — the ocean moves as much heat poleward as the atmosphere does.
- What would happen if all the insects died? Far worse than losing bees — decomposition, pollination and the base of most terrestrial food webs would fail together.
- What would happen if the Amazon rainforest burned? It holds well over a hundred gigatonnes of carbon and generates much of its own rainfall — losing it would change climate far beyond South America.
- What would happen if all the bacteria disappeared? Complex life would end within years — nitrogen fixation, decomposition and digestion all run on bacteria.
- What would happen if the Earth stopped moving in its orbit? It would fall into the Sun in about 65 days.
Common questions
- What would happen if the Sun went out?
- Eight minutes and twenty seconds of normality, then permanent night — and surface temperatures below freezing within a week.
- How certain is that?
- Reasoned extrapolation. This is a reasoned extrapolation rather than an observation. The mechanism is understood, but the scale of the consequences depends on assumptions that could reasonably be argued differently.
Related pages
- What would happen if the Earth stopped spinning? Everything not bolted down would keep moving east at up to 465 metres per second, and the oceans would migrate to the poles.
- What would happen if the Earth lost the Moon? Tides would drop to about a third, nights would be dark, and Earth's axial tilt would eventually wander.
- What would happen if all the ice on Earth melted? Sea level would rise by about 70 metres, redrawing every coastline on the planet.
- What would happen if all the bees died? Serious, expensive and not civilisation-ending — most staple calories come from wind-pollinated grasses.
- What would happen if the Earth's magnetic field flipped? It has flipped hundreds of times already, most recently 780,000 years ago, with no mass extinction attached.
- What would happen if all the trees disappeared? A carbon and water-cycle catastrophe — but not suffocation, because most oxygen production is marine and the atmosphere holds a huge reserve.
- What would happen if the Earth spun twice as fast? A twelve-hour day, more violent weather, and everyone at the equator about 1.4 per cent lighter.
- What would happen if the Moon were closer to Earth? Tides scale as the inverse cube of distance — at half the distance they would be eight times larger.
- What happens if you stop eating sugar? Your body
- What happens if you stop drinking alcohol? Your body
- What happens if you stop smoking? Your body
- What happens if you stop eating meat? Your body
- What happens if you crack your knuckles every day? Your body
- What happens if you swallow gum? Your body
Sources
- NASA — National Aeronautics and Space Administration (Public domain (US Government))