Making double planets
Explore the formation of Pluto's Charon and Earth's Moon with computer simulations.
How do astronomers explore events that occurred billions of years ago, involved energies we can hardly imagine, and transformed a portion of a planet into molten rock?
The best way to date is through detailed computer simulations. Astronomers encode the rules of physics into a model that includes characteristics of a planet's composition, such as rock or ice; the effects of gravity; the sizes, speed, and masses of planet and impactor; and many other parameters. Then they set up the collision and watch what happens.