Earth does not spin upright relative to its orbital plane (the flat disk of its path around the Sun). Instead, it is tilted at an angle of approximately 23.5 degrees—an angle known as its . This tilt is the single most important reason for the seasons. It means that as Earth orbits the Sun, first the Northern Hemisphere and then the Southern Hemisphere leans toward our star, receiving more direct, concentrated solar radiation.
For daily wit & wisdom, sign up for the Almanac newsletter. ... Planning activities, gardening, or just curious? Here are the star... The Old Farmer’s Almanac When Do Seasons Start and End? - Time and Date When Do Seasons Start and End? * 1. Astronomical Seasons. The astronomical definition uses the dates of equinoxes and solstices to... Time and Date Meteorological and Astronomical Seasons: Southern Hemisphere ... Meteorological and Astronomical Seasons: Southern Hemisphere graphic * Image. * Caption. Do you know the difference between meteor... NOAA (.gov) Show all Spring (Vernal Equinox): March 20 Summer (Summer Solstice): June 21 Fall (Autumnal Equinox): September 22 Winter (Winter Solstice): December 21 The Old Farmer’s Almanac +4 3. The Southern Hemisphere Flip If you are south of the equator (e.g., Australia, Brazil, or South Africa), the seasons are the exact opposite: The Old Farmer’s Almanac +1 December to February: Summer March to May: Fall June to August: Winter September to November: Spring Time and Date +1 Why Do We Have Seasons? Seasons occur because the Earth is tilted
The equinoxes are the "shoulder seasons"—the moments of maximum change in day length, where the migration of direct sunlight across the equator triggers profound biological and meteorological shifts. when are the seasons
A deeper layer of complexity comes from —a slow, 26,000-year wobble of Earth’s rotational axis, like a spinning top. This means the orientation of the tilt changes relative to the stars and relative to the point of perihelion. Over thousands of years, the date of the solstices relative to Earth's orbit shifts.
In about 13,000 years, the Northern Hemisphere will experience summer at perihelion (closest point to the Sun), leading to far more extreme seasonal contrasts (hotter summers, colder winters). Today, summer occurs near aphelion (farthest point), making Northern summers slightly milder. This slow drift means the "when" of the seasons, in terms of orbital context, is not fixed over geological time. Earth does not spin upright relative to its
Occurs around September 21st–24th. The Sun crosses the celestial equator moving southward. Again, day and night are roughly equal globally. This begins astronomical autumn in the north and spring in the south.
The Earth's rotation on its axis and its orbit around the Sun are the fundamental drivers of the seasons. The planet's axis of rotation is tilted at an angle of approximately 23.5 degrees relative to the plane of its orbit around the Sun. This axial tilt, also known as the obliquity of the ecliptic, is responsible for the changing seasons. It means that as Earth orbits the Sun,
The seasons bring various changes in weather patterns, including: