Experiencing Zero Shadow Day in Mumbai: A rare and Spectacular Astronomical Event


A zero shadow day is a unique event that occurs when the Sun is positioned directly overhead at noon, causing objects on the ground to not cast any shadows. This phenomenon occurs because the Sun’s rays are perpendicular to the Earth’s surface, resulting in no visible shadows for a few minutes at solar noon.

Solar noon is when the Sun reaches the highest point in the night sky appearing directly overhead, casting shadows at their shortest length. In ancient times 12PM was marked as the time when solar noon occurs but the exact time of solar noon varies depending on the location and time of the year, as it is influenced by the Earth’s tilt and orbit around the Sun.

No Shadow Day in Mumbai
No Shadow Day in Mumbai

What is Zero Shadow Day?

 Zero Shadow Day is a rare astronomical event that occurs twice a year, around the time of the equinoxes. An equinox is experienced when the Sun is directly above the equator, resulting in almost equal amounts of daytime and nighttime in both hemispheres. During these times the sun’s rays fall perpendicular to the surface of the Earth resulting in the shorting of our shadows, appearing as if we are standing on our own shadows, hence the term ‘zero shadows’.

Zero Shadow Day happens depending on the latitude of the place. The latitude should be near the Tropic of Cancer (around 23.5 degrees North of the equator) or the Tropic of Capricorn (around 23.26 degrees South of the equator). The Tropic of Cancer passes through many states of India and Mumbai which is around 19.07 degrees North of the equator also experiences zero shadow day.

Being close to the Tropic of Cancer, Mumbai also experiences zero shadow days twice a year, around the vernal equinox in March and the autumn equinox in September. The date and time at which it occurs is different for every location.

On the equinox, the Earth's axis is perpendicular to the Sun's rays.
On the equinox, the Earth’s axis is perpendicular to the Sun’s rays.

Why is Zero Shadow Day significant?

Zero Shadow Day is a wonderful astronomical event as it can be seen and experienced without the help of any sophisticated equipment like a telescope or binoculars and doesn’t require deep knowledge of physics. It also helps us understand the movement of Earth around the Sun and its position relative to the Sun.

In Iran, zero shadow day has an important cultural significance as it is celebrated as Nowruz, the Persian New Year.

How to Witness Zero Shadow Day

Many states in India like Hyderabad have already experienced zero shadow day and you may have seen photos or videos of it in the news or on the internet. Determining the time when this event will occur is important. First find the exact time of solar noon. If you are in Mumbai on the 15th of May then solar noon will be around 12:35 pm but can vary slightly depending on your location.

Once you have determined the time, go to an open space like a park or rooftop or any place with a clear view of the sky. As solar noon approaches you’ll see your shadow disappearing. Any object near you like a pole will have no shadow and it will appear to be floating in the air.

You can take pictures of yourself and of the objects near you as they appear and tag us on Instagram at stargazingmumbai.

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