Astronomy
Solstices & Equinoxes
The 4 seasonal markers of the solar year — March & September equinoxes and June & December solstices. Each marks a turning point in the Sun's apparent motion and has deep significance in Vedic tradition.
Next Seasonal Marker
September Equinox
Sharad Vishuva · Sharad Sampat
23 Sep 2026, 05:35 IST
in 63 days
Upcoming Seasonal Markers
Sanskrit: Sharad Vishuva · Sharad Sampat
Day & night equal length worldwide. Marks start of autumn in Northern Hemisphere and spring in Southern. Sun crosses celestial equator moving southward.
Sanskrit: Dakshinayana Sankranti · Uttarayana Aarambha
Shortest day in Northern Hemisphere, longest in Southern. Sun reaches its southernmost point. From this day the sun begins its northward (Uttarayana) journey — considered highly auspicious in Vedic tradition. Makara Sankranti follows in ~3 weeks.
Sanskrit: Vasant Vishuva · Vasant Sampat
Day & night equal length worldwide. Marks start of spring in Northern Hemisphere and autumn in Southern. Sun crosses celestial equator moving northward. In Vedic tradition, this is Vasant Sampat — the spring equinox.
Sanskrit: Uttarayana Sankranti · Dakshinayana Aarambha
Longest day in Northern Hemisphere, shortest in Southern. Sun reaches its northernmost point. From this day the sun begins its southward (Dakshinayana) journey. Pitru Paksha begins in many regions.
What Are Solstices & Equinoxes?
The Earth orbits the Sun on a plane called the ecliptic, but its rotation axis is tilted by 23.5° relative to that plane. As Earth moves around the Sun, this tilt causes the Sun's apparent position to shift north and south over the course of a year, producing the seasons.
Equinoxes (Latin aequus nox, "equal night") occur when the Sun crosses the celestial equator. On these two days — around March 20 and September 22 — day and night are approximately equal in length everywhere on Earth. The March equinox marks the start of spring in the Northern Hemisphere and autumn in the Southern; the September equinox marks the reverse.
Solstices (Latin sol stitium, "stationary sun") occur when the Sun reaches its northernmost or southernmost point relative to the celestial equator. The June solstice (~June 21) is the longest day in the Northern Hemisphere and shortest in the Southern. The December solstice (~December 21) is the opposite.
Together, the four seasonal markers divide the solar year into four roughly equal quarters of about 91 days each. They are the astronomical foundation of all solar calendars, including the Vedic solar calendar that underlies festivals like Makara Sankranti and Karka Sankranti.
Vedic Significance
Uttarayana (उत्तरायण)
The Sun's six-month northward journey, beginning at the December solstice. Considered highly auspicious in Vedic tradition — Bhishma Pitamah chose to wait for Uttarayana to leave his body. Makara Sankranti (~Jan 14) marks the Vedic start of Uttarayana, when the Sun enters Capricorn. This period is favored for auspicious activities: marriage, housewarming, sacred thread ceremonies, and starting new ventures.
Dakshinayana (दक्षिणायण)
The Sun's six-month southward journey, beginning at the June solstice. Considered less auspicious for new beginnings. Karka Sankranti (~Jul 16) marks the Vedic start. Pitru Paksha (the fortnight of ancestors) falls during Dakshinayana. Many traditional households avoid weddings, gruhapravesham, and upanayanam during Chaturmas (the four months of Dakshinayana, roughly July–November).
Vasant Sampat (वसन्त सम्पात)
The spring equinox — when day and night are equal and the Sun crosses into the Northern Hemisphere. Vasant Panchami, dedicated to Goddess Saraswati, falls near this time. This is also the start of the Vedic new year in many regional calendars (Ugadi, Yugadi, Baisakhi). The Vedic astrological new year is calculated from the New Moon following the Vasant Sampat.
Sharad Sampat (शरद् सम्पात)
The autumn equinox — when day and night are again equal and the Sun crosses into the Southern Hemisphere. Sharad Navratri (the nine-night festival dedicated to Goddess Durga) falls near this time, culminating in Dussehra. Sharad Purnima, the harvest full moon, is celebrated by many communities with kheer left under moonlight.
Solstice vs Sankranti — What's the Difference?
A common point of confusion: the December solstice (~Dec 21) and Makara Sankranti (~Jan 14) are not the same day, even though both mark the "beginning of Uttarayana". The ~24-day difference is due to precession of the equinoxes — the slow wobble of Earth's axis that shifts the zodiac by about 1° every 72 years. Vedic astrology (Lahiri ayanamsa) accounts for this precession, so the Sun enters Capricorn (Makara) around Jan 14 in the sidereal zodiac, even though the solstice itself occurs on Dec 21 in the tropical zodiac.
Roughly 1,700 years ago, the December solstice and Makara Sankranti fell on the same day. As precession continues, they will drift further apart. This is also why the Vedic month names (Chaitra, Vaishakha, etc.) no longer align with the solar seasons they were originally named after — a slow astronomical shift that takes ~26,000 years to complete one full cycle.