What is Samvatsara?
There can be many explanations but I like to keep it simple. Samvatsara means "a year" in Sanskrit, this calendar is calculated based on the sidereal solar (vedic) year combined with the Jovian (Jupiter) cycle and Saturn's cycle around the zodiac belt. First let's see what a Solar year is.
Vedic Solar year
It starts when the Sun enters the zodiac of Aries and ends when the Sun leaves Pisces. It's approximately 365.25 days a year. It usually starts on 14th/15th of April every year. It is more accurate and easier to follow than the lunar or luni-solar calendars. One full cycle of the Sun from Aries to Pisces is called one Solar year. It's the same as Gregorian year but starts at the time of April, that's the difference.
The same way, we have solar months in comparison to lunar months. Since Sun takes (approximately) 30 days to transit a zodiac, it is called a solar month. Sun usually enters a sign in the mid of every Gregorian month. It enters Aries on 14th/15th of April then Taurus on 14th/15th of May and so on.
The entry of the Sun in every zodiac is called Sankranti.
Sankranti = Sankar (Sun) + Anti (entry) = entry of the Sun into a zodiac. Sun’s entry into Aries is called Mesha Sankranti, Taurus is called Rishabha Sankranti, Capricorn is called Makara Sankranti and so on. Every month is named after their monthly themes. I’ve written about all of them here.
A Jovian cycle is the cycle of Jupiter from Aries to Pisces. Jupiter takes 12 years to finish one full cycle of all the zodiacs. It means one Jovian cycle is the equivalent of 12 years on earth. In other words, Jupiter takes one year to transit a zodiac so the influence of Jupiter on that zodiac will be stronger in that period than any other planet (in transit astrology). Based on this context, our sages named every year with the theme of Jupiter's influence in mind.
Now coming back to the Samvatsara, there are a total of 60 years in the Samvatsara calendar with each of them having a different theme. The ancient scriptures named them properly based on their associated themes. So what happens after 60 years? Simple, the cycle starts again. It means we witness the same theme once again every 60 years, that's why we say history repeats itself. The themes are also based on relative positions of Sun, Jupiter and Saturn. But most importantly Jupiter like I said earlier. That's why Samvatsara is usually called Jovian years because of its dominance.
But why 60 years exactly? Why not more or less?
Take the most important grahas of the solar system. The Sun, Jupiter and Saturn. All three meet at the same point every 60 years. For ex., if Sun, Jupiter and Saturn start their journey from 0 degree Aries today then they’ll meet each other exactly at the same sign at the same degree after 60 years on the same day (approximate). So their meeting after every 60 years starts a new cycle once again. Understanding this, our ancestors bestowed us this incredible calendar system with which we can easily find the themes of every year. This calendar is still in practice in South India mainly in the states of Tamilnadu and Kerala.
Prabhava 21. Sarvajita 41. Plavanga
Vibhava 22. Sarvadhari 42. Keelaka
Sukla 23. Virodhi 43. Saumya
Pramodhuta 24. Vikruti 44. Sadharana
Prachorpati 25. Khara 45. Virodhakrutu
Aangirasa 26. Nandana 46. Paridhabi
Srimukha 27. Vijaya 47. Pramadhisa
Bhava 28. Jaya 48. Ananda
Yuva 29. Manmadha 49. Rakshasa
Dhata 30. Durmukha 50. Nala/Anala
Eswara 31. Hevilambi 51. Pingala
Bahudhanya 32. Vilambi 52. Kalayukti
Pramathi 33. Vikari 53. Siddharti
Vikrama 34. Sarvari 54. Raudra
Vishu 35. Plava 55. Durmathi
Chitrabhanu 36. Subhakrutu 56. Dundhubi
Subhanu 37. Sobhakrutu 57. Rudhrodhgari
Tarana 38. Krodhi 58. Raktakshi
Parthiba 39. Visvavasu 59. Krodhana
Vyaya 40. Parabhava 60. Akshaya
Sun enters Aries on 14th of April 2022, so the name of this year is Shubha Krutu (சுபக்கிருது/शुभकृत). Also known as Shubha Kritu. It means creating auspiciousness through good deeds. So the result of this year would be about creating new/fresh karma using guidance, wisdom and freewill coming through Jupiter in Pisces.