What is Zero Shadow Day, and how does it occur?

→ Zero Shadow Day, also called "Noon Solar Day" or "Nilasundar Din," is a special event in the sky that happens in certain places on Earth.

→ On this day, things on the ground don't make a shadow for a short time when the sun is right above.

→ This happens only two times in a year, around March 20-21 and September 22-23, during the equinoxes.

→ Zero Shadow Day happens because of how the Earth leans and moves around the sun. This is why it occurs:

Axial Tilt
Equinoxes
Zero Angle of Incidence
Specific Latitudes

(1). Axial Tilt

→ The Earth leans over a bit as it goes around the sun.

→ This tilt is like bending a stick a little.

→ Because of this tilt, the sun shines on the ground from the side sometimes, not straight down.

→ This makes things make shadows on the ground, especially on most days of the year.

(2). Equinoxes

→ During the times when the seasons change (spring and autumn), the Earth tilts in a way that the sun is right above the middle of the Earth, called the equator.

→ This makes the sunlight shine straight down on the equator, making it almost like a straight line.

→ This happens when the sun is highest in the sky around noon on these days.

(3). Zero Angle of Incidence

→ When the sun is right above us, its light comes straight down onto the ground.

→ This makes things have very short shadows or no shadows at all because the sun's light goes straight down.

(4). Specific Latitudes

→ Zero Shadow Day happens near the middle of the Earth, not too far away.

→ It's on the days when day and night are almost the same length.

→ When you move away from the middle towards the top or bottom of the Earth, the shadow you make gets bigger.

→ And if you go really close to the very top or bottom, the shadow becomes even longer.

→ It's important to remember that Zero Shadow Day happens in places close to the middle of the Earth.

→ You can't see it in places that are farther from there.

→ When you go away from the middle of the Earth, the sun's light comes from the side, so the shadows become longer, even when it's almost noon.

→ Watching Zero Shadow Day helps us see how the Earth leans and how this connects to where the sun is in the sky.

→ This is a really interesting thing that shows how the Earth spins, tilts, and moves around the sun.

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