1 year ago
Last edited at 2:20PM on 2/17/2013
Even an impact by a Mars-sized body failed to dislodge Earth from its orbit around the Sun, although the impact probably did change our axis of spin to the present 23.5 degrees to the plane of the solar system. To escape the Sun, Earth would require a speed of 11,000 mph (5 km/s) over its orbital speed of 67,000 mph (30 km/s). It's difficult to envision a force that could accelerate the mass of Earth to such a speed and therefore improbable Earth will ever escape the Sun.
Earth may have been in a slightly different orbit before the Mars-sized body hit it but is unlikely to change much in the future. Earth's orbit has been relatively stable for over four billion years with little sign of change in its predictable orbits for at least the next five billion years. Although the Sun is shrinking slightly, astronomers believe this is a temporary contraction and has negligible effect on Earth's orbit.