New Delhi: Day and night will be of equal duration on Thursday, marking the beginning of autumn in northern hemisphere.
During an autumnal equinox, the sun shines directly overhead as viewed from the earth`s equator.
"An equinox happens twice every year, when there is a location on the earth`s equator where the centre of the sun can be observed to be vertically overhead, occurring around March 20/21 and Sep 22/23 each year," said Chandrabhushan Devgun of the Science Popularisation Association of Communicators and Educators (SPACE).
Devgun said on these two dates, the day and the night are of equal lengths anywhere on the surface of the earth.
SPACE will be performing public outreach at Jantar Mantar to explain to people the concept of equinox, using the ancient instruments. The programme will be held from 11 a.m. to 4 p.m.
"Telescopes and solar filter goggles will be set up for solar observations. Large number of students have registered with us to participate in the several activities to be conducted during the day," he said.