Yuga
Yuga is a long period of time as defined in Hindu scriptures; there are four yugas: Satya, Treta, Dwapara and Kali.
Etymology
In Sanskrit, Yuga means era, the age.
About Yuga
Please understand the Yuga. In Sanskrit, Yuga means era, the age.
It is not dependent on sun and the moon moving, it is dependent on the collective mind moving.
'Even based on the sun and moon’s movements, as per the calendar, external calendar, the time for kali yuga to end is already happening. It is not as you expect 42,000 years. As per the vedic astrology the conclusion of the kali yuga is already happening. May be we are 400 years ahead, that’s all. So that can easily be equated by the movement of the collective minds. That is why I am saying, Satya yuga, the NIthya yuga is already started happening. You will see the proof for this word by 2015. 2015, you will see the proof. Solid proof. = HH Paramahamsa Nithyananda Paramashivam
References
http://www.nithyananda.org/video/qaperformance-means-being-total#gsc.tab=0