The Earth doesn't emit a single dominant wavelength, but rather a spectrum of wavelengths. However, the peak of Earth's emitted radiation falls within the infrared region of the electromagnetic spectrum.

This is due to Earth's relatively low temperature compared to the Sun. The peak wavelength emitted by a blackbody (an ideal object that absorbs and emits all radiation) is determined by Wien's Displacement Law:

λ_max = b/T

Where:

* λ_max is the peak wavelength (in meters)

* b is Wien's displacement constant (2.898 x 10^-3 m·K)

* T is the temperature (in Kelvin)

The average temperature of Earth's surface is approximately 288 K (15°C), leading to a peak wavelength of around 10 μm. This falls within the infrared region, specifically the thermal infrared range.

Therefore, while the Earth emits radiation across a wide range of wavelengths, the majority of its energy is emitted in the infrared region, peaking around 10 μm.