We think that gravitons can have any wavelength and any energy, just like the particles of light, called photons. Gravitons (gravity waves) would be emitted by accelerating masses, just as photons (electromagnetic waves) are emitted by accelerating electrical charges. The particular wavelengths of electromagnetic waves depend on the source- radio transmitters, lasers, etc. The same would hold for gravity waves- the wavelength depends on how the mass in the source is accelerating around.
Actually, my first statement may not be quite right. There is reason to suspect that gravitons with wavelengths less than about
1/100,000,000,000,000,000,000,000,000,000,000 centimeters might not exist. Since no gravitons have yet been observed, that may not be worth worrying about yet.
(published on 10/22/2007)