Update 23 Mar 2024: Zero shadow at 1.11pm on March 23 in Singapore
The bollards outside Stadium MRT station did not cast a shadow at 1.11pm on March 23. ST FOTO:SHINTARO TAY
A Lahaina Noon phenomenon, where one’s shadow appears minimal, took place at 1.11pm on March 23 in Singapore. Also known as zero shadow day, it is a natural event in which objects standing upright, such as a stick or pole, will cast no shadow.
Professor Matthias Roth, who teaches geography at the National University of Singapore, said the phenomenon will also happen on Sept 19 at 12.58pm, when the solar altitude is as close to or at 90 degrees. He noted that the phenomenon on March 23 comes about four days after the start of the spring astronomical season, which is determined by the position of the Earth in relation to the Sun.
As Singapore is not exactly on the Equator, the midday sun will be overhead only about four days after the astronomical spring equinox, Prof Roth added. The astronomical spring equinox results in an equal amount of daylight and darkness. “Due to historical reasons, Singapore’s time is one hour ahead compared with the solar time. This means that solar noon does not occur until about 1pm, rather than noon, which also explains why sunrise and sunset times are observed at about 7am and 7pm respectively.”
Earth, like nearly all the planets, orbits the Sun in a tilted fashion
There are only two moments each year when neither pole points toward the Sun, and the Sun lies directly above Earth’s equator. These moments are the equinoxes.
The March equinox happens sometime between March 19 and 21. The September equinox occurs sometime between September 21 and 24.
In the Northern Hemisphere, the March equinox is also known as the spring or vernal equinox; the September equinox can be called the fall or autumnal equinox. In the Southern Hemisphere, the names are the other way around. On the date of the equinox, at any location, the lengths of day and night are roughly equal.
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What is an Equinox?
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An equinox is one of the two times of the year when the amount of daylight and nighttime hours are just about of equal length. The two equinoxes occur around March 20–21 and September 22–23.
The equinoxes occur on these days, but an equinox is not the whole day—it is the moment when the sun is directly above Earth’s equator. The word equinox can also refer to the position of the sun at this moment. This can also be called the equinoctial point. The equinoxes are traditionally considered to mark the start of spring and fall. In the Northern Hemisphere, the vernal equinox (or spring equinox) occurs in March and the autumnal equinox occurs in September. In the Southern Hemisphere, it’s the reverse.
In contrast, a solstice is one of the two times of the year when the positioning and tilt of Earth relative to the sun results in the most amount of daylight time or the least amount of daylight time in a single day. There are two solstices during the year: one that occurs around June 20–22 (usually June 20 or 21) and one that occurs around December 20–23 (usually December 21 or 22). In the Northern Hemisphere, the summer solstice occurs in June and the winter solstice occurs in December. In the Southern Hemisphere, it’s the reverse.
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