What would happen if the Earth stopped moving in its orbit?

Earth stays in orbit because its sideways velocity of roughly 29.8 kilometres per second exactly balances the Sun's pull. Remove that velocity and there is nothing left but the pull, so the planet falls straight in. The free-fall time can be computed from Kepler's third law by treating the fall as a degenerate ellipse, and it comes to the orbital period divided by four times the square root of two — about 64.6 days. The fall would accelerate steeply: most of the distance is covered in the final days, and Earth would be moving at hundreds of kilometres per second by the end. Conditions would become uninhabitable long before arrival, with solar heating rising as the inverse square of distance — roughly four times current levels at half the distance, reached after about 50 days.

What happens, in order

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 Sun went out? Eight minutes and twenty seconds of normality, then permanent night — and surface temperatures below freezing within a week.
• 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.