We are said to be currently in Lord Brahma’s 51^st day and. Each day has 2 Kalpa’s one for day and one for night. In the day it consist of 1000 Maha yugs (a Maha yug equals 4 Yugs – satyag {1,728,000 human year}, tretyug {1,296,000 human years}, dwarpa yug {864,000 human years} and kaliyug {432,000 human years}). The other Kalpa is Lord Brahmas night which is annihilation when there will be the water of inundation