  We study the gravitational bremsstrahlung owing to collisions mediated by a
$1/r$ potential. We combine classical and first order Born approximation
results in order to construct an approximate gravitational `Gaunt factor' for
the total emitted energy. We also obtain the cross-section with an angular
momentum cut-off, and hence the cross-section for emission via close hyperbolic
encounters in a gravitating cluster. These effects are the dominant source of
very high frequency gravitational noise in the solar system. The total
gravitational wave power of the Sun is $76\pm 20\,$MW.
