Jakarta, Indonesia Sentinel — The rare phenomenon known as “Shadowless Day,” or solar culmination, is expected to sweep across the island of Java this week, occurring between October 8 and 14, 2024. Indonesia’s Meteorology, Climatology, and Geophysics Agency (BMKG) explains that culmination occurs when the Sun reaches its highest point in the sky, directly above an observer at solar noon.
This phenomenon, officially called the “Main Culmination,” happens when the Sun’s declination aligns precisely with the latitude of the observer’s location. As a result, during the culmination, shadows of upright objects disappear momentarily, as the shadow falls directly underneath the object. This is why the event is also referred to as “Shadowless Day.”
BMKG attributes this phenomenon to the fact that Earth’s rotational axis and the plane of its orbit around the Sun (known as the ecliptic) are not perfectly aligned. Throughout the year, the Sun’s position relative to Earth shifts between 23.5° north and 23.5° south latitude, creating what is known as the Sun’s apparent motion. This motion is part of an annual solar cycle that consistently repeats.
Ida Pramuwardani, the Head of Weather Prediction and Early Warning at BMKG, offered further insight into this event. “Shadowless Day is the result of the Sun reaching its highest position in the sky,” she explained. “When the Sun’s declination aligns with the Earth’s equatorial plane and the observer’s latitude, it is referred to as the Main Culmination, commonly known as Shadowless Day.”
On that day, the Sun will be positioned directly overhead, causing the shadow of any upright object to disappear, as it aligns perfectly with the object.
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Despite the Sun’s maximum intensity during this event, Ida emphasized that it will not lead to a significant increase in temperature. “While sunlight will reach its peak intensity, this does not necessarily cause a sharp rise in surface temperature, especially in regions experiencing Shadowless Day,” she noted.
This is because temperature changes are influenced by multiple factors, including cloud cover, humidity levels, and the potential for rainfall.
The Shadowless Day phenomenon is part of the natural movement of the Sun and will continue to be a regular occurrence.
(Raidi/Agung)
