yottajoules

A yottajoule (symbol YJ) is the SI unit of energy equal to 10^24 joules. It uses the SI prefix yotta, which denotes a factor of 10^24, making the yottajoule one of the largest standard energy units.

In terms of larger SI units, 1 yottajoule equals 1,000 zettajoules or 1,000,000 exajoules. This places it far above the scale of typical human energy use and well into the domain of astronomical or planetary energy budgets.

Conversions to common energy measures include approximately 2.8 × 10^11 terawatt-hours (TWh). That is, one yottajoule is about 278 billion TWh, a scale far beyond annual energy consumption of civilizations on Earth.

Usage and context: The yottajoule is employed for extremely large energy magnitudes, such as theoretical comparisons in astrophysics, discussions of stellar or galactic energy scales, or planetary energy budgets. In practical terms, global energy consumption per year is on the order of 10^17–10^18 joules, which is roughly 10^(-7) yottajoules, illustrating how rarely a YJ is required in everyday discussions.

Notes: The yotta prefix represents the upper end of SI prefixes, and yottajoules are used chiefly for concepts that vastly exceed human-scale energies. For most terrestrial contexts, exajoules, zettajoules, or terawatt-hours are more common units.