A very unenergetic wavelength, or frequency, of light. Radio waves are the least energetic form of radiation known. They have wavelengths longer than 10^-3 meters and frequencies less than 10^11 Hz. Radio waves are not harmful to life because they are not strong enough to ionize atoms or destroy cells. While the Earth's atmosphere shields us from some radio radiation, it does allow radio waves in the vicinity of VHF, UHF, and FM frequencies to pass through. Astronomers study waves that pass through this "radio window" with large radio telescopes or antennas, which resemble giant satellite dishes. Often, many radio antennas are coordinated together to synthesize even bigger telescopes, such as the Very Large Array in New Mexico. In addition to astronomy, radio waves have many useful applications on Earth, such as television and radio broadcasts and RADAR.