Here's why:
* Earth's Temperature: Earth's average surface temperature is about 15°C (59°F).
* Wien's Displacement Law: This law states that the wavelength at which an object emits the most radiation is inversely proportional to its temperature. The hotter the object, the shorter the wavelength of peak emission.
* Infrared Radiation: Objects at Earth's temperature emit most of their radiation in the infrared part of the electromagnetic spectrum.
Important Note: While the peak of Earth's radiation is in the infrared, we also emit some radiation at other wavelengths, including visible light. That's why we can see the sun, but we can't "see" the infrared radiation emitted by the Earth.
