Astronomy   View all facts   Glossary   Help
abstraction > mathematical concept > unit > time unit > second unit > leap second
Next second unitmean solar second    Upsecond unit    Previous second unitephemeris second   

leap second comparison table
Subject is an instance of is a kind of has definition
second unit time unit 
leap secondsecond unit A second (see second, Système International) added between 60s and 0s at announced times to keep UTC within 0s.90 of UT1. Generally, leap seconds are added at the end of June or December.

Next second unitmean solar second    Upsecond unit    Previous second unitephemeris second