Could an asteroid knock Earth out of its orbit?
Impact from space wouldn’t make much of a difference to the Earth’s momentum or could be the end of the world as we know it.
Asked by: Chris Wisner, South Carolina, USA
No. The Earth has a lot of mass and moves extremely quickly in its orbit around the Sun; in science speak, we say its ‘momentum’ is large. To significantly change the Earth’s orbit, you would have to impart a very great change to the Earth’s momentum. Not even the largest asteroids have sufficient mass and kinetic energy to make much of a difference to the Earth’s momentum.
Even more of an obstacle is the fact that our planet’s binding energy is greater than its orbital kinetic energy. This means that any object large enough to change the Earth’s orbit is also big enough to completely destroy it!