How does heat transfer through vacuum?

Heat transfer through a vacuum occurs primarily through radiation because conduction and convection, the other two modes of heat transfer, require a medium (such as a solid, liquid, or gas) to transfer heat. Here's a brief explanation of each mode of heat transfer and how they apply in a vacuum:

Radiation:

Radiation is the transfer of heat in the form of electromagnetic waves, mainly infrared radiation, which does not require a medium to propagate. It can transfer heat through a vacuum because it involves the emission, absorption, and transmission of electromagnetic waves.
All objects with a temperature above absolute zero emit thermal radiation. The rate of radiation is proportional to the fourth power of the absolute temperature of the object, as described by the Stefan-Boltzmann law.
For example, the Sun's energy reaches Earth through the vacuum of space via radiation. Similarly, objects in space exchange heat through radiation.
Conduction:

Conduction is the transfer of heat through direct contact between particles in a material. It occurs when hotter particles transfer kinetic energy to adjacent cooler particles, leading to a flow of heat.
In a vacuum, there are no particles to facilitate conduction, so this mode of heat transfer does not occur in the absence of a medium.
Convection:

Convection involves the transfer of heat through the movement of a fluid (liquid or gas). This movement is typically driven by temperature differences within the fluid, causing warmer, less dense fluid to rise and cooler, denser fluid to sink.
In a vacuum, there is no fluid to carry heat, so convection cannot occur.
In summary, heat transfer through a vacuum primarily relies on radiation. Objects in a vacuum can emit and absorb thermal radiation, allowing them to exchange heat energy despite the absence of a medium for conduction and convection. This principle is fundamental in various scientific and engineering contexts, including spacecraft design, where managing heat transfer in the vacuum of space is crucial to spacecraft's thermal control systems.