A hot object radiates heat to its surrounding bodies at lower temperatures due to the fundamental principle of heat transfer known as the second law of thermodynamics. This law states that heat naturally flows from objects at higher temperatures to objects at lower temperatures until thermal equilibrium is reached.
Heat transfer occurs through various mechanisms, such as conduction, convection, and radiation. In the case of radiation, which is relevant to this question, objects at any temperature above absolute zero (-273.15 degrees Celsius or -459.67 degrees Fahrenheit) emit electromagnetic radiation in the form of photons. This radiation includes a broad spectrum of wavelengths, with the specific distribution determined by the temperature of the object.
When a hot object is in contact with cooler surroundings, such as the air or other objects, it emits thermal radiation in the form of photons. These photons carry energy, and as they are emitted from the hotter object, they travel through space and can be absorbed by cooler objects in their path. When the photons are absorbed by a cooler body, they transfer their energy to that body, increasing its internal energy and temperature. This process continues until the temperatures of the objects reach a state of equilibrium, where the heat transfer between them becomes balanced and no further net energy exchange occurs.
In summary, a hot object radiates heat to surrounding bodies at lower temperatures through the emission of thermal radiation in the form of photons. This transfer of energy occurs in accordance with the second law of thermodynamics, which governs the direction of heat flow from higher temperature regions to lower temperature regions.