When the Sun transits into the Cancer sign, people belonging to the Hindu community observe the Karka Sankranti. In Hinduism, Karka means Cancer sign. This will mark the end of the six months of the Uttarayana Period and the onset of Dakshinayan, Lord Sun's southern journey. The Dakshinayana will end on Makar Sankranti next year.
People on this day worship Lord Vishnu.
Devotees wake up early in the morning and freshen up.
They then bathe and wear clean or new clothes.
After this, they offer Arghya to Lord Surya and chant 'Om Adityaya Namah'.
Chanting the mantra for 108 times is considered to be quite beneficial and auspicious.
Then you can worship Lord Vishnu with Kumkum, Tulsi leaves, incense sticks, flowers and by lighting a Diya (earthen lamp). Also, offer seasonal fruits to the deity and chant his prayers.
A banyan or peepal tree is planted by the devotees of Lord Vishnu.
This Sankranti is considered to be a favourable time for Pitru Tarpan, the time when departed souls get peace.
The main aim of worshipping on this Sankranti is to get rid of the hardships of life.
People visit Lord Vishnu's temple and offer prayers to him.
However, this time period isn't considered auspicious for initiating any holy work. This is because of the onset of Chaturmas, the four months during which Lord Vishnu sleeps or meditates.
Also, devotees believe that the Lord Sun too goes towards the south to take rest. Due to this, Lord Shiva along with other Gods looks after the world. Hence, people worship Lord Shiva during these months.