When and What Is an Autumnal Equinox?

Autumnal Equinox
Autumnal Equinox

An Equinox is a celestial phenomena where the equatorial plane of Earth passes through the center of the Sun. Let me tell you more about an Autumnal Equinox.

What is an Autumnal equinox?

In simplest words, an Equinox is that day of the year when the rays of Sun fall straight on the Earth’s equator. Due to this phenomenon, the length of day and night on the Earth is almost equal during the Equinox.

An equinox always occur two times in a year. The timing for Equinox in every year is usually 20 March and 23 September. As the name suggests, autumnal equinox is the equinox that occurs during the month of September every year.

Due to it’s time of occurrence Autumnal Equinox is also called September Equinox.

The Autumnal Equinox definition can be given as the Astronomical phenomenon where the rays of Sun falls straight on the Equator of the Earth during the month of September.

autumnal equinox illustration
Autumnal Equinox Illustration. Image Courtesy timeanddate.com

What is date and time of September Equinox 2017?

The September Equinox also known as Autumnal Equinox 2017 will occur on:
September 22, 2017 (Friday) at 20:02(UTC) in Northern Hemisphere.

Why Equinox?

The word Equinox is derived from a Latin word aequinoctium. Aequus means equal and Nox (general form noctis) means Night. So Equinox means the time of a year when the night and the day are equal.

September Equinox
September Equinox Day and Night

What and When is Solstice?

Like Equinox, Solstice is also an astronomical event. During the Solstice, the day on Earth either gets the most sunlight of the year or it gets the least sunlight on any place on Earth other than the Equator.

Just like Equinox, Solstice occurs twice every year. The usual timing of Solstice each year is around 21 June and 22 December.

2005 Summer Solstice Sunrise over Stonehenge
2005 Summer Solstice Sunrise over Stonehenge

Effects of Equinox and Solstice

The Equinoxes and Solstices combined, are directly in relation with different seasons on Earth.

seasons change during equinox and solstice
seasons change during equinox and solstice

Mythology and Naming Traditions

During an Equinox, the seasons on either side of the Earth’s equator are different. In fact, there are completely opposite seasons on each hemisphere.

– In the Northern Hemisphere, the September Equinox marks the beginning of the Autumn (fall) Season. So, September Equinox is also know as Autumn Equinox or Fall Equinox.

– In the Southern Hemisphere, the March Equinox marks the beginning of the Spring (vernal) Season. So, March Equinox is also known as Spring Equinox or Vernal Equinox.

An ancient celebration of Equinox

The Pyramid Chichen Itza, Mexico is a very famous pyramid. It has staircases running all the way from bottom to top on each of its four faces. The stairs of this pyramid are constructed in a very geometrical and calculated manner. Each stair is created and placed at a specific measured angle. At the very bottom of the pyramid stairs, is created a giant snake head.

Snake of Sunlight during Equinox
Snake of Sunlight at Chichen Itza, Mexico during Equinox

Due to such amazing art of construction, when the sunlight falls on the stairs of Chichen Itza during an Autumnal Equinox, it looks as if a giant snake is descending from top of the pyramid. This whole occurrence is world famous by the name ‘The Snake of Sunlight’.

Autumnal Equinox Rituals, Customs and celebrations

– China

In China, the Moon festival also known as the Mid-Autumnal Festival is celebrated during the Fall Equinox time. It is celebrated by the abundance of the summer’s harvest. A very special food for the festival is the Mooncake. Mooncake is prepared by fillings of lotus, sesame seeds and a duck egg or dried fruits.

mooncakes in mid-autumn festival
mooncakes in mid-autumn festival

– Ancient Greece

In the ancient Greek mythology, Autumn is the time when a Goddess named Persephone had went back to the underworld in order to be with her husband, Hades.

Persephone and Hades
Persephone and Hades

– Japan

In Japan, both Autumnal Equinox and Spring Equinox are observed as national holidays. During this time, Higan-e or Higan – a week of Buddhist services is observed in Japan. The word Higan, which means “other shore”, refers to the spirits of the dead attaining Nirvana – the freedom from circle of life and death. During Higan, people remember the dead by visiting, cleaning and decorating their graves.

Higan in Autumnal Equinox

10 Facts about September Equinox

  1. September Equinox is the second equinox of the year. The first equinox occurs during 21 March also known as March Equinox.
  2. In Northern Hemisphere, the Autumn or Fall Season starts and Summer season ends during September Equinox.
  3. In Southern Hemisphere, the Spring or Vernal Season starts during September Equinox.
  4. Some amazing phenomena takes place at specific places on the Earth. The Equinox at Chichen Itza, Mexico is an example for this.
  5. The Autumnal Equinox usually occurs during 22 or 23 September. But it can also take place on 21 or 24 September.
  6. The 21 September Equinox has not occurred since 1000 CE. In 21st Century, September 21 Equinox will happen in 2092 and 2096.
  7. The September 24 Equinox had last happened in 1931 and next one will occur in 2303.
  8. Equinox means ‘Equal night’, which has led people to misinterpretation that every place on Earth observes 12 hours of day and night.
  9. On day of Equinox, most places on Earth sees more than 12 hours of daylight.
  10. According to NASA, the chances of occurring Northern Lights are more during a September Equinox.
Northern Lights in Alberta, Canada
Northern Lights in Alberta, Canada