Plate tectonics give Earth its mountains, earthquakes, continental drift and maybe even helped give rise to life itself. But ...

Earth grew to its final size through one last major collision with another Mars-sized object. This last collision, also known as the “moon-forming impact,” was so large that—in addition to adding lots ...

Alinda is one of the five largest near-Earth asteroids, coming closer than 9.3 million miles until the year 2200.