From the passage provided, provide the two scenarios in bullet form where radiative heat transfer is an important consideration.

Context: Radiative heat transfer is the transfer of energy via thermal radiation, i.e., electromagnetic waves. It occurs across vacuum or any transparent medium. Thermal radiation is emitted by all objects at temperatures above absolute zero, due to random movements of atoms and molecules in matter. Since these atoms and molecules are composed of charged particles, their movement results in the emission of electromagnetic radiation which carries away energy. Radiation is typically only important in engineering applications for very hot objects, or for objects with a large temperature difference.

Answer: Radiative heat transfer is an important consideration when:
- Engineering applications for very hot objects
- Engineering applications for objects with a large temperature difference