What would happen if earth stops revolving around the sun?

The Earth orbits the Sun once every 365 days, or one full year. It does this while whizzing through the vacuum of space at break-neck speeds of up to 110,000 kilometers per hour. Many of us take the Earth’s orbit around the Sun for granted, but as it turns out, life would be different (if not entirely nonexistent) if the Earth stopped orbiting the star at the center of our solar system.

"If Earth stopped revolving around the sun, it would either fly out of its orbit and into outer space, or it would fall into the sun. If it flew out of its orbit, everything on Earth would be moving at 30 km/s and would fly off the planet. If it fell into the sun, it would take around 65 days for the planet to crash. During this time, the Earth would experience an intense heat wave, and most of life as we know it would be destroyed."

If it happened quickly, then results would be catastrophic, turning the whole planet into a blended slurry of mountains, oceans and trees, hurtling past at hundreds of kilometers per hour. And if it happened slowly, it would still be unpleasant, as we stopped having a proper day/night cycle. But it wouldn't be immediately lethal.

But would happen if the Earth somehow just stopped in its tracks as it was orbiting the sun, as if it ran into an invisible wall? As with the Earth turning question, it's completely and totally impossible; it's not going to happen. And with the unspun Earth, it would be totally devastating and super interesting to imagine.

Before we begin to imagine the horrifying consequences of a total loss of orbital velocity, let's examine the physics involved.

Earth’s Orbital Velocity:

Right now, Earth revolves around the Sun at a staggering speed of 30 kilometers per second (70,000 miles per hour)! (Source) Of course, we don’t realize we’re going so fast because everything on Earth is moving at the same speed. That means there is no relative speed that could possibly give us any idea of our orbital velocity.

What If Earth Suddenly Stopped Revolving Around The Sun?

In the case of a sudden halt of Earth’s revolution around the heat giant, everything would fall into complete disarray on the planet. You see, since Earth has an orbital velocity, everything on Earth is moving at the same velocity. In the case of a sudden stop, everything on Earth would still have 30 km/s worth of inertia.

To put it in perspective, think of what inertia does to you when a bus driver suddenly applies the brakes. In this case, Earth is the bus and everything that it hosts (including all mountains, seas, rocks and every single lifeform) represent the passengers. Note that Earth’s escape velocity is 11.2 km/s (Source). With an inertia of 30 km/s, things on the leading side would fly off into space, while everything on the trailing side would be crushed against Earth’s surface by an incredibly powerful force. In short, complete destruction in a matter of seconds is what I’m talking about

How long would it take? 

The calculations of Dave Rothstein from Cornell's Ask an Astronomer. According to Dr. Rothstein, the whole journey would take about 65 days. It would take 41 days to cross the orbit of Venus, and on day 57, we'd cross the orbit of Mercury.

As they days went by, the Earth would get hotter and hotter as it got closer to the sun. Aatish Bhatia over at WIRED did some further calculations to figure out the temperature. A month into the freefall, and the average temperature on Earth would have risen to 50 degrees C. 50 days in and we'd be about 125 C. On the final day, we'd get up to 3,000 C… and then, that would be that.

Of course, this is completely and totally impossible. There's no force that could just stop the Earth in its tracks like that. There is, however, a plausible scenario that might drag the Earth into the sun.

In the far future, the sun will turn into a red giant and expand outward, engulfing the orbits of Mercury and Venus. There's still an argument among astronomers on whether it's going to gobble up Earth as well.

Let's say it does. In that case, the Earth will be inside the atmosphere of the sun, and experience a friction from the solar material as it orbits around, and spiral inward. Of course, at this point you're orbiting inside the sun, so falling into the sun already happened.

There you go. If the Earth happened to stop dead in its orbit, it would take about 65 days to plunge down into the sun, disappearing in a puff of plasma. 

Deep Explanations :

If the Earth lost its rotational inertia and stopped spinning on its axis (something that would take an almost indescribable amount of energy to do), the end result would not be the total cessation of any rotation, but rather the tidal locking of the Earth to the sun, just as the moon is tidally locked to the Earth.

Due to the gravitational influence of the sun, the Earth with no rotational energy will be forced to rotate at the same period as our orbit, meaning that one full rotation would take a year and one side of the Earth would be in permanent sunlight, and the other side in permanent darkness.

This is not an ideal situation for any inhabitants that may be on the planet at the time, as it means that the sunlit side would be exposed to a constant 120 degC and the dark side would be at minus 120 degC. This would result in the seas literally boiling on the sunlit side, and freezing solid on the dark side. There would be a ring around the planet at the effective solar horizon that would have a habitable temperature range, since it would be in eternal twilight.

There still would be seasons though, since the planet would retain its inclination of 23.5 degrees. This would result in the strongest seasons being present at either pole, with the most uniform conditions being present at the equator.

The huge difference in temperatures between the sunlit and dark hemispheres would result in the migration of all the surface water from the hot side towards the cold, with precipitation at the twilight zone tending to run back towards the hot side. This then establishes a working hydrologic cycle that might enable life to hang on in these areas, so such a scenario is not necessarily the end of life on Earth, although the available habitat is greatly diminished.

Edit; It has become clear in the comments section that many are unaware of what exactly “tidal locking” actually means. Tidal locking is not the cessation of all rotational motion, but rather the synchronising of the rotational period with the orbital period. Having a planet that rotates one full turn every year is still a planet that is rotating.

The other misconception is that a tidally locked body is rigidly attached to its parent. Some people have gone as far as showing pictures of clock faces to demonstrate how relative motion is not possible. At no point is tidal locking a rigid, mechanical union of the two bodies, they still are free to have relative motion within the constrains of their gravitational influences and a good example of that is our own moon, which we all can agree is tidally locked to our planet.

Here you can see the libration of the moon, which means that despite being tidally locked with us, we can see more than just 50% of the satellite. This is thanks to the 1.5 degrees of inclination its rotational axis has with respect to its orbital plane, assisted in this case by a 28.5 degree inclination with respect to the Earths equator.

As you can see, we have a tidally locked moon that has an axial inclination in its rotation, as well as an inclination relative to the ecliptic plane. The moon makes these “freedoms” even more stark when you consider that it doesn’t even have a circular orbit, but rather has a distinct amount of eccentricity (which changes its apparent size from Earth), yet at the same time it is still “tidally locked” with us.

Assuming our gravitational bind to the Sun were somehow lost, we would hypothetically be carried off by our momentum at 63° to the ecliptic plane of the Milky Way. If we were lucky, we'd be carried into the Milky Way. It wouldn't save us, but long after we perish our rock might eventually regain some of what it would lose by encountering any of the ~150 million inner star systems. A million-billion-to-one chance we'd smash into a young earth-like body and become its moon the way a large planetoid became our moon. Then that civilization would speculate about all sorts of ridiculous things and my ghost would be immensely amused.

Aside from motion, without the sun's energy we would rely on our quickly dissipating interior energy. No plants would grow. Animals would die. Republicans would deny it happened and blame Democrats and gays. Soon enough, our mantle would cool, we'd lose our magnetosphere, we'd lose our atmosphere, and we'd lose our stock portfolio. Somehow we'd still owe taxes. We'd die long before the sun drags the Oort cloud past our path, which is a shame. I'd've liked to've seen evidence of it.

The sun would continue on its course around the galactic center, completely ignorant that it had lost some little rock. Pluto would give us his rocky-icy middle finger and say "Look who's not a planet now!"