What are your thoughts? If Earth lost it's orbit or our sun fizzled out without destroying it, could we survive underground?
What would happen if earth got knocked out of orbit?
In: Astronomy [Edit categories]
The collision required to knock the earth out of orbit would be much too massive for the earth to survive. The earth would simply be destroyed by the massive collision and the remains of the earth would either fly off into space of collide with other objects.
If this is purely a hypothetical.. If the earth did, somehow, (even though it is impossible) get knocked out of orbit, it would die. Without a constant source of energy like the Sun (which indirectly provides all energy on earth), the earth would eventually run out of resources and die.
There are a few possible mechanisms for this scenario
1) Giant impact with another planet, it would take an object the size of Venus or larger. This would obliterate both planets.
2) Premature solar nova. Theoretically, if the sun went nova (but not supernova) right now, without going through the red giant phase, the sudden drop in its mass would drastically reduce its gravity, effectively releasing earth from its orbit. Earth would fly off on a path tangent to its orbit. This would effectively be a moot point to anything living on the surface, since the waves of superheated solar plasma jettisoned from the sun would burn the earth to a crisp within a half hour. However, if the sun lost enough mass from another process, like the mother of all coronal mass ejections, earth could survive provided it was on the opposite side of the sun.
3) Near miss by a rouge gas-giant planet. If, say, Jupiter or Saturn fell off their orbits toward the sun, and passed within maybe .25 AU (astronomical unit), it's gravity could accelerate earth in its orbit just enough to fly out of orbit. Provided, or course, earth isn't engulfed by the gas giant. This would likely result from orbital resonance between the gas giants, their moons, and the sun.
4) Fly-by from another star or a small black hole. If a massive object, like a neutron star or a black hole, passed within a quarter of a light year of our sun (still technically within our solar system) the orbits of all the inner planets would be disturbed. Provided the object wasn't headed straight for our sun, its gravity could at some point cancel out the suns, and earth would be essentially floating unbound to anything, and drift off. Or the far more likely thing being the objects gravity overpowering the suns, and slingshotting earth off into deep space. Either one works. There would be a considerable chance that tidal forces from the object and the sun's gravity would tear earth apart, however.
5) Orbital resonance between the earth, sun, moon, and some other object. If the earths orbit began to resonate with the moon and sun, the resulting force could provide enough of a push to accelerate earth out of orbit of the sun. This would likely require the gravity of another planet, most likely Mars, to finish the job. This would be the most likely scenario, and the most survivable, not requiring a cataclysm to happen. Similar events are responsible for the existence of so called "Hot Jupiter" planets.
Whatever the cause of earth going rogue, there are only three possible chain of events, and one outcome, after earth starts to drift.
If Earth went rouge, scientists and astronomers would realize it within days if not almost immediately, by noticing deviation between where the stars are and where their supposed to be. Most of us wouldn't notice a change for some time, since the moon would stay with the earth, and the stellar changes would be subtle for the first few weeks, as we'd be moving off at a tangent to our former orbit. After about three months, the change in the position of the stars would so drastic that anyone could be it. The zodiac would stop advancing, and the stars would be drifting in a straight line. Now, the sun's "life zone" extends from inside Venus' orbit to well beyond Mars' orbit, so weather effects would take years to show up. But, the sun would rapidly grow dimmer in the sky, and the moon with it. By the time Earth crossed Mars' orbit, the climate would be in the early years of an ice age, and most of Earth's plant life would be dying out from lack of sunlight. To survive, humanity would have to move under ground, like in Dr. Strangelove.
Deep caves or mine shafts would be adequate, but the deeper the better. About a mile and a half deep the there would be plenty of geothermal energy to power a technological society. It would be warm too. And you'd want to be as deep as possible, for reasons discussed later. Crops could be grown in hydroponic farms. Livestock could be raised in facilities similar to today's corporate owned farms. The biggest problem would ironically be people. Without any prior warning about Earth going rogue, we would never be able to save the entire human race, instead at most a few million could be saved. These people would have to chosen from the best of humanity, with emphasis on higher intelligence and expertize in science, math, and engineering. No athletes, bankers, stock brokers, or career politicians. Religion would have to be abandoned too. It would also be necessary to exclude career artists and musicians, as they have no useful skills. Instead you'd want engineers/scientists/professionals who also happen to be artists. It may even be necessary to exclude certain ethnic groups, to ensure genetic stability. Contrary to movies like 2012 or Deep Impact, a lottery system would a terrible way to select survivors, as would letting people buy entry to the shelter. Instead a computer would have to be used. You wouldn't want anyone over the age of 35 too. The location of the entry points, or even the entire program's existence, would have to kept a secrete to protect the facilities and the survivors from those weren't chosen. The shelters would have to be sealed shut, and their existence all but erased on the surface, long before Earth freezes.
At earth's average orbital speed, it would take us about 3 years to cross Mars' orbit. While still in our solar system, there would be a small chance of Earth colliding with another planet, which would destroy it. There would also be a 100% chance of it drifting through the asteroid belt. A planetary collision is extremely unlikely, but asteroid collisions are all but certain. About 3-5 years after earth went rogue, the surface would be essentially frozen solid, and the worst is yet to come. Earth would drift into the asteroid belt, and get pummeled with more steroids and meteors than have hit it in its entire life time. Anything still somehow alive on the surface would surely be destroyed, along with any evidence of human existence on the surface. The impacts would not be enough to destroy the earth, but would pulverize the outer crust. So, any underground shelters would have to be extremely deep, at least 1.5 miles. It would be a good idea to build them under high mountain ranges. The endless asteroid barrage would last the better part of a decade.
After exiting the belt, Earth would essentially be free and clear, provided it doesn't collide with a gas giant. With the distances between the outer planets, such a collision would be very unlikely. Earth would drift through the outer solar system for the next few decades with little change. 30-50 years after going rogue, Earth would drift into the Kuiper belt, a field of comets a small planetoids roughly the size of Pluto. The risk of collision would be minimal, however, because of the immense distance between objects out there, often greater than 5 AU. Th most interesting thing would be passing through the heliopause; the point where the sun's solar wind goes from super sonic to subsonic, essentially a giant sonic boom in space. This phenomenon may have destroyed on of the voyager probes, and would probably strip earth of any atmosphere in had left. Maybe 300 years after going rogue, Earth would pass through the Oort Cloud, a field of millions of comets about a light year from the sun, and effectively exit our solar system. As a rogue planet, Earth would orbit the galactic center along with the sun and the rest of the Sagittarius Arm. There is a minuscule chance of entering another nearby star system. or colliding with another star, but this is extremely unlikely.
Planetary collision and asteroid bombardment could be avoided if the Earth was also knocked off its orbital plane.
While drifting rogue, earth would remain geologically active. The decay of uranium at the Earth's core will last for the next billion or so years, and the residual heat would last another 5 or 6 billion years. In fact had earth stayed in its original orbit, the sun would die before the earth did, and consume it in the process. Also life could survive in some of the deeper ocean trenches, more than 5 miles down. Provided we dug in deep enough, humanity could survive for millions of years, and eventually colonize other star systems as earth passed close to them.
Of course this is just theoretical, and is not likely to ever happen.