How much more massive would Pluto have to be to clear its neighborhood? How much more massive would Pluto have to be to clear its neighborhood?
This Wikipedia page does a decent job of describing the orbit-clearing criterion, based on the original paper by Stern &amp; Levison (2002), which can be found here (PDF).

In order to have cleared its orbit over a period of billions of years, an object needs a "Stern-Levison parameter" $\Lambda$ which is $&gt; 1$; Pluto has $\Lambda \approx 3$-$4 \times 10^{-3}$. Since $\Lambda$ depends on the square of the object's mass (see the Wikipedia page, or Equation 4 of Stern &amp; Levison), Pluto would need to be about fifteen to twenty times its current mass in order to cross the threshold.