Hyperbolic orbit
= Hyperbolic orbit
{title2=$e>1,\quad\varepsilon>0$}
An unbound <Kepler orbit> under attractive <inverse-square law> <gravity> is a <hyperbola> with the attracting center at a <focus of a conic>. Writing $\mu=GM$ and $h$ for <angular momentum> per unit <mass>, its <eccentricity> satisfies $e^2=1+2\varepsilon h^2/\mu^2$, where $\varepsilon>0$ is the <specific orbital energy>. A nonzero incoming <speed> $v$ at infinity gives $\varepsilon=v^2/2$.