Caption: 
 This SwRI animation shows a projectile 3,000 km in diameter crashing into the nascent Earth at a speed of 19 km/sec. At right, the model shows the interaction of projectile and terrestrial materials. Green indicates silicate particles from both the mantle of the Earth and the projectile, while white indicates metallic particles from the projectile’s core. Light brown indicates particles from the Earth's core. At left, the same model reflects the temperature of the particles.