A foe is a unit of energy equal to 1044 joules. To measure the large amount of energy produced by a supernova, specialists occasionally use a unit of energy known as a "foe", an acronym derived from the phrase [ten to the power] fifty-one ergs, or 1051 ergs. This unit of measure is convenient because a supernova typically releases about one foe of observable energy in a very short period (which can be measured in seconds). In comparison, if the Sun had its current luminosity throughout its entire lifetime, it would produce 3.827×1026 W × 1010 years ≈ 1.2 foe.
