Why is the Hindu New Year on different days — Gudi Padwa, Ugādi, Puthāṇḍu, Baisakhi?

some regions start the year by the Moon (Caitra Śukla Pratipadā), others by the Sun’s entry into Aries (Meṣa Saṅkrānti).

India has two main calendar families. The lunisolar calendar, used in Maharashtra, Karnataka, Andhra Pradesh and Telangana, begins the year on the first day after the new moon of Caitra. That day is Gudi Padwa for Marathi families, who raise a Gudi, a pole with a bright cloth, an upturned kalaśa, neem leaves and a sugar garland, and Ugādi for Telugu and Kannada families, who eat Ugādi pachaḍi (Kannada bevu-bella), a mix of six tastes for life’s joys and sorrows, and hear the pañcāṅga śravaṇam.

The solar calendar, used in Tamil Nadu, Kerala, Punjab, Assam, Bengal and Odisha, begins when the Sun enters Meṣa, usually around 14 April: Puthāṇḍu, Viṣu, Baisākhī, Bohāg Bihu, Pohela Boishākh and Pana Saṅkrānti. Gujarat begins its year the day after Dīpāvalī.

All are correct; they simply count from different heavenly markers.

Lunisolar: Caitra Śukla Pratipadā · Solar: Meṣa Saṅkrānti · Source: regional pañcāṅga traditions

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