Truth can not be suppressed and always is the ultimate victor.

About 12 Sankranti

Makara Sankranti and Karka Sankranti are two Ayan Sankranti which are also known as Uttarayana(6months time period when sun moves into Northern hemisphere) Sankranthi and Dakshinayana(6months time period when sun moves into Southern hemisphere) Sankranthi respectively. These are conceptually equivalent to winter solstice and summer solstice in Hindu

Uttarayana is six month time period when the Sun moves into Northern hemisphere and Dakshinayana is remaining six month time period when the Sun moves into Southern hemisphere. Due to precession of the Earth these definitions of Ayan Sankranti(s) have become incorrect.

The Sun God, also known as Surya Dev, starts moving into Northern hemisphere about 24 days before Makara Sankranti. Currently Makara Sankranti occurs on 14th or 15th January while Winter Solstice, the movement of the Sun from Southern to Northern hemisphere, starts on 21st or 22nd December.

Correct positioning of Stars is foundation of Hindu calendar and any likely correction will invalidate whole concept of Sidereal Astrology. During Makara Sankranti the Sun God coincides with same Stars in the background which was the original (and is still) concept to mark the day of Makara Sankranti. During Winter Solstice, the Sun doesn't coincide with same Stars in the background which is must to mark the day of Makara Sankranti. Hence Hindu calendar doesn't respect seasons and let them drift but maintain the same position of the Sun (with respect to Stars in the background) to mark the day of all Sankranti(s) including Makara Sankranti.

According to above explanation, Hindus still celebrate Makara Sankranti on right day however the word Uttarayana has become misnomer with time and most Indians have accepted this fact by ignoring Winter Solstice and Summer Solstice for any religious activities.

Similarly Dakshinayana when the Sun God starts moving into Southern hemisphere falls on 21st or 22nd June about 24 days before Karka Sankranti. Karka Sankranti currently occurs on 15th or 16th July which has drifted apart from Summer Solstice by 24 days.

For Ayan Sankranti auspicious time period is well written in religious texts. For Makara Sankranti 40 Ghati(s) after Sankranti and for Karka Sankranti 30 Ghati(s) before Sankranti is auspicious for doing all rituals related to Sankranti.

Mesha Sankranti and Tula Sankranti are two Vishuva Sankranti which are also known as Vasant Sampat and Sharad Sampat respectively. These are conceptually equivalent to Vernal Equinox and Autumnal Equinox in Hindu calendar and these Vishuva Sankranti(s) are drifting apart from seasonal Equinoxes due to precession of the Earth. After thousands of years these Vishuva Sankranti(s) will coincide again with seasonal Equinoxes.

For these two Sankranti(s) fifteen Ghati(s) before and after Sankranti moments are considered for auspicious activities.

Simha Sankranti, Kumbha Sankranti, Vrishabha Sankranti and Vrischika Sankranti are four Vishnupadi Sankranti. For all these four Sankranti(s) sixteen Ghati(s) before Sankranti moments are considered for auspicious activities.

Meena Sankranti, Kanya Sankranti, Mithuna Sankranti and Dhanu Sankranti are four Shadshit-mukhi Sankranti. For all these four Sankranti(s) sixteen Ghati(s) after Sankranti moments are considered for auspicious activities.