Planet formation is violent, slow and messy

The collisions that spawn planets are bigger and take place over longer periods of time than previously thought, say astronomers who studied nearly 300 stars with NASA’s Spitzer Space Telescope. The new cache of data gives astronomers fresh hope that Earth-like planets might be common in the universe.
Planets are thought to grow as dust collides and sometimes sticks together in the discs around young stars. Until now, most theorists suspected the process was relatively smooth, with dust clumps building up gradually through successive collisions.
Article: Planet formation is violent, slow and messy – New Scientist