Gaṇeśa Caturthī · the fourth lunar day in several observance settings
Gaṇeśa Caturthī
Gaṇeśa is widely honored as the remover of obstacles and the deity invoked at beginnings. Caturthī means the fourth tithi. The shared word connects several observances whose specific identities depend on the lunar fortnight, the time examined, and sometimes the lunar month.
What is going on in the sky?
Caturthī is a moving Moon–Sun interval.
Every tithi spans 12 degrees of Moon–Sun elongation. Śukla Caturthī, the fourth tithi after New Moon, covers 36 to 48 degrees. Kṛṣṇa Caturthī, the fourth tithi after Full Moon, covers 216 to 228 degrees. Either interval may begin or end at any clock time.
Two monthly observances
The teaching calendar checks the two monthly Caturthīs at different times.
A bright-fortnight observance. This teaching calendar checks whether Śukla Caturthī prevails at madhyāhna, represented here by the midpoint between local sunrise and sunset.
A dark-fortnight vrata. This teaching calendar checks whether Kṛṣṇa Caturthī prevails at candrodaya, the local moonrise. Practices may include fasting until moonrise, prayer, and Gaṇeśa pūjā.
These calendar rules assign each observance to a civil date. Caturthī itself remains the full 12-degree Moon–Sun interval.
The familiar annual festival
Bhādrapada turns the monthly pattern into the named annual festival.
The major annual Gaṇeśa Caturthī—also called Vināyaka Caturthī and celebrated in many places as Gaṇeśa's birth or appearance festival—is associated with Śukla Caturthī in the lunar month of Bhādrapada. It may include Gaṇeśa pūjā, installation of an image, processions, offerings, and immersion according to regional and community practice.
Open Pañcāṅga identifies the annual festival when Śukla Caturthī prevails at madhyāhna during the regular amānta month Bhādrapada. When those annual rules match, Open Pañcāṅga shows Gaṇeśa Caturthī instead of repeating the monthly Vināyakī Caturthī observance. Other calendars may use a different month system or additional date-assignment details.
How we learned about these dates
The monthly Caturthīs and the annual festival come from different sources.
Sewell and Dīkṣita's historical calendar tables describe the recurring monthly Caturthī timings. The Government of India's Incredible India guide explains that the annual Gaṇeśa Caturthī festival is celebrated on Bhādrapada Śukla Caturthī and describes regional traditions. Calendars and communities may apply additional details, so dates can sometimes differ.