A tropical phenomenon, twice a year
Zero Shadow Day — Hari Tanpa Bayangan
There is a day when the sun stands directly over your head. At midday your shadow disappears beneath your feet. It happens everywhere in Indonesia, twice a year.
Why does it happen? · Learn more
The sun drifts through the year
The point on Earth directly beneath the sun does not stay put. It travels north until June, then back south until December.
Twice, it passes your town
Indonesia lies between those two limits, so that point crosses every city in the country twice a year — once going north, once coming back.
That day, the shadow goes
With the sun straight overhead, a vertical object has no shadow in any direction. It lasts a couple of minutes, and then the shadow returns.
The latitude directly beneath the sun sweeps between 23.44°N and 23.44°S over the year. Indonesia lies entirely inside that band, from Sabang at 5.9°N to Rote at 11°S. So every place in the country gets two zero shadow days: once as the sweep heads north, once as it returns. Nowhere in Europe, North America, or most of China ever gets one.
Shadows point north for part of the year and south for the rest. Outside the tropics they only ever point one way.
Solar noon is not 12:00. WIB is anchored to 105°E while Banda Aceh sits near 95°E — nearly ten degrees west, so its solar noon runs roughly forty minutes later than the clock implies.
Go deeper
- ShadowTurn the view, drag the time, and watch the shadow shorten until it is gone.
- For schoolsMeasure the EarthMeasure the circumference of the Earth with two sticks and a ruler.
- Shadow trailsThe trace of the shadow’s tip through a day, and the figure-eight the sun draws.
- AnalemmaThe figure of eight the sun draws over a year.
- Archipelago mapWatch the sun’s band sweep across the archipelago through the year.