Lahaina Noon phenomenon: Near zero shadow at 1.11pm on 23 Mar & 12.58pm on 19 Sep in Singapore
A Lahaina Noon phenomenon, where one's shadow appears minimal, took place at 1.11pm on March 23. 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. The phenomenon will also happen on Sept 19 at 12.58pm, when the solar altitude is as close to or at 90 degrees.
Lahaina Noon
Lāhainā Noon, also known as a zero shadow day, is a semi-annual tropical solar phenomenon when the Sun culminates at the zenith at solar noon, passing directly overhead (above the subsolar point). As a result, the sun's rays will fall exactly vertical relative to an object on the ground and cast no observable shadow.
A zero shadow day occurs twice a year for locations in the tropics (between the Tropic of Cancer at latitude 23.4° N and the Tropic of Capricorn at 23.4° S) when the Sun's declination becomes equal to the latitude of the location, so that the date varies by location. The term "Lāhainā Noon" was coined by the Bishop Museum in Hawaiʻi. The subsolar point travels through the tropics. Hawaiʻi is the only US state in the tropics and thus the only one to experience Lāhainā Noon. In 2022 and 2023, the phenomenon occurred in Honolulu on May 26 and July 16. Hawaii and other locations between the Tropic of Cancer and Tropic of Capricorn receive the sun's direct rays as the apparent path of the sun passes overhead before and after the summer solstice.
Lāhainā Noon can occur anywhere from 12:16 to 12:43 p.m. Hawaii–Aleutian Standard Time. At that moment objects that stand straight up (flagpoles, bollards, telephone poles, etc.) cast no outward shadow. The most southerly points in Hawaii experience Lāhainā Noon on earlier and later dates than the northern parts. For example, in 2001 Hilo on the Island of Hawaiʻi encountered the overhead sun around May 18 and July 24, Kahului, Maui, on May 24 and July 18, Honolulu, Oʻahu, on May 26 and July 15 and Līhuʻe, Kauaʻi, on May 31 and July 11. Between each pair of dates, the sun is slightly to the north at solar noon. Chosen in a contest sponsored by the Bishop Museum in the 1990s, Lāhainā Noon was the selected appellation because lā hainā (the old name for Lāhainā, Hawaii) means "cruel sun" in the Hawaiian language. The ancient Hawaiian name for the event was kau ka lā i ka lolo which translates as "the sun rests on the brains.
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
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.”
Autumn Equinox 2024 秋分 Qiūfēn
Autumn starts this year on Sunday 22 September and ends on 21 December 2024. Or does it? You may have heard us already talking about autumn in the weather forecasts.
This is because the astronomical autumn begins at the autumn equinox (22 September this year) but the meteorological one always starts on 1 September. For meteorological records it is preferable to group the seasons into three-month periods with the northern hemisphere autumn being September, October and November. This makes year-on-year comparisons easier. The word "equinox" is derived from Latin and literally translates to "equal night". On these days, everywhere on Earth experiences roughly 12 hours of sunshine and 12 hours of darkness.
The Earth's axis is titled at an average of 23.5°. As the Earth travels on its year-long path around the Sun it is tilted towards or away from the Sun, which gives us our seasons. But, on the day of an equinox, the tilt of Earth's axis is perpendicular to the Sun's rays, producing a nearly equal amount of day and night all over the world. Normally, the autumn equinox falls between 22 and 24 September, and this year the equinox occurs on 22 September at 13:44 BST.