Autumnal Equinox – Heralding the beginning of Fall in the Northern Hemisphere

Autumnal Equinox

Autumn Equinox or September equinox is occurring on this September 22nd, 2016 at 14:21 UTC (19:51 IST). This also heralds the first day of  fall (autumnal equinox) in the Northern Hemisphere and the first day of spring (vernal equinox) in the Southern Hemisphere.

An equinox is the astronomical event when Sun crosses the celestial equator (extended plane of Earth’s equator), which means that Sun is exactly overhead at a point on the equator.

The word equinox has derived from Latin aequinoctium, aequus (equal) and nox (night). At equinox, day and night are of approximately equal duration all over the planet. As a result, the Northern and Southern hemisphere are equally illuminated.

Twice each year, Sun comes exactly overhead on the equator and thus each year there are two equinox:

  • Spring Equinox
  • Autumn Equinox

Today is the last day of summer. Autumn equinox begins on the 22nd at 10:21 EST. The word equinox means “equal night”; night and day are about the same length of time. During the equinox, the Sun crosses what we call the “celestial equator” from north to south. At this point, the amount of nighttime and daytime are roughly equal to each other.

The event is celebrated in the whole world as astronomical event and seasonal festival. SPACE conducts ‘Project Paridhi’ on this day.

‘Project Paridhi’ is a flagship project of SPACE, to popularize hands on science. It is a showcase for proving that science can be best learnt by doing. It is open to all age groups and the public. It is typically conducted on days of Equinoxes and Solstices.

Description of Activity
This is a hands on science activity which involves measuring the length of shadows cast by a vertical object (gnomon) as cast by the sun, to determine the local noon. Simple trigonometry leads to the calculation of the circumference using the measured sun angle. The activity replicates that done by Eratosthenes in 2300 BC.

Learning Outcomes and Benefits to Schools
Participants learn basic concepts of science in a fun way with hands on science and use geometry and trigonometry. Some are trained as Earth Scientists and conduct the training, which hones leadership skills. Schools can host this for the neighbourhood to showcase their schools.

To Know More About Project Paridhi:


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