Makar Sankranti and Thai Pongal are two of many festivals celebrated by Hindus in January. Occurring on the same day, although observed in different ways, depending on the region, the festivals bring together groups of people in countries such as India, Nepal and Sri Lanka, symbolising the end of the winter solstice and the beginning of the harvest season. In southern areas such as Sri Lanka, Tamil Nadu and Puducherry the festival is referred to as Thai Pongal.

Throughout the celebrations, devotees convey their appreciation to the Sun God, showing their gratitude for providing the energy for agriculture. Part of the celebration consists of boiling of the first rice of the season or cooking traditional sweet dishes on open fires. Many Indians combine the occasion with the winter solstice with others marking the day by taking a dip at Ganga Sagar, the point where the River Ganges meets the Bay of Bengal.

Hindu ritual
Indian Hindu devotees arrive to take a holy bath and perform rituals at the Gangasagar Island, near Kolkata, IndiaDibyangshu Sarkar/ Getty Images
Hindu ritual
Indian Hindu devotees pour water over a sadhu, a 'holy man' – as they take a holy bath and perform rituals at the Gangasagar Island, IndiaDibyangshu Sarkar/ Getty Images
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A Sri Lankan vendor prepares flower garlands at a Hindu temple in Colombo. Hindus in Sri Lanka are celebrating the Thai Pongal festival, which worships and offers thanks to the Sun god.Ishara S.Kodikara/ Getty Images
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Devotees prepare ritual rice dishes to offer to the Hindu Sun God as they attend Pongal celebrations at a slum in Mumbai, IndiaDanish Siddiqui/ Reuters
Hindu ritual
They prepare a traditional sweet dish on open fires, during the Pongal celebrations in Mumbai, IndiaIndranil Mukherjee/ Getty Images
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Hindu devotees offer prayers at Sangam, the confluence of the Ganges, Yamuna and Saraswati rivers, on a foggy winter morning, on the occasion of Makar Sankranti festival in Allahabad, IndiaJitendra Prakash/ Reuters
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A Hindu pilgrim walks back after taking a dip at the confluence of the river Ganges and the Bay of Bengal, ahead of the Makar Sankranti festival at Sagar Island, south of Kolkata, IndiaRupak De Chowdhuri/ Reuters
Hindu ritual
A devotee reacts to smoke as others prepare ritual rice dishes to offer to the Hindu Sun God as they attend Pongal celebrations at a slum in Mumbai, IndiaDanish Siddiqui/ Reuters
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A Sadhu or a Hindu holy man takes a dip at Sangam, the confluence of the Ganges, Yamuna and Saraswati rivers on the occasion of Makar Sankranti festival in Allahabad, IndiaJitendra Prakash/ Reuters

As part of the festival, devotees take a dip in the holy river Ganges to worship the Sun God and to purify their souls. It also marks the arrival of spring season in India.

Hindu ritual
A Hindu pilgrim offers prayers at the confluence of the river Ganges and the Bay of Bengal on the occasion of Makar Sankranti festival at Sagar Island, south of Kolkata, IndiaRupak De Chowdhuri/ Reuters
Hindu ritual
A Hindu pilgrim uses a mobile phone to take pictures of her relative at the confluence of the river Ganges and the Bay of Bengal on the occasion of Makar Sankranti festival at Sagar Island, south of Kolkata, IndiaRupak De Chowdhuri/ Reuters
Hindu ritual
A Hindu devotee holds a candle and burning incense sticks as she prays after taking a dip in the waters of river Howrah on the occasion of Makar Sankranti festival on the outskirts of Agartala, IndiaJayanta Dey/ Reuters
Hindu ritual
Hindu pilgrims seek blessings from a cow after taking a dip at the confluence of the river Ganges and the Bay of Bengal, ahead of the Makar Sankranti festival at Sagar Island, south of Kolkata, IndiaRupak De Chowdhuri/ Reuters
Hindu ritual
Hindu devotees take a holy dip and perform rituals at Gangasagar Island, IndiaDibyangshu Sarkar/ Getty Images
Hindu ritual
Indian Hindu devotees take a holy bath before performing rituals at the Gangasagar Island, IndiaDibyangshu Sarkar/ Getty Images