The typical wavelength of a gamma ray is very small, less than 1 x 10 to the negative 11th power, or 0.000000000001 meter. These rays have the shortest wavelength and the highest frequency of all forms of electromagnetic radiation and are the most energetic detected photons as of May 2014.
On Earth, gamma rays are produced by nuclear decay and in experimentation with nuclear fusion and nuclear fission, according to About.com. They are also produced by events taking place in the universe, such as colliding or collapsing stars. The length of radio waves, by comparison, are much longer at greater than 0.1 meter, and they have a lower frequency.