ZERO SHADOW DAY - GEOGRAPHY
News: Bengaluru
sees Zero Shadow Day: What is it, why does it happen
What's in the news?
● At
12:17 pm on Tuesday (April 25), Bengaluru experienced a ‘Zero Shadow Day’, when
vertical objects appear to cast no shadow.
Key takeaways:
● The
Zero Shadow Day was because the sun was at its zenith, and so the shadow was directly under the object.
Zero Shadow Day:
● ‘Zero
Shadow Day’ is an astronomical event that occurs
twice a year on specific dates in some parts of the world.
● It
is a phenomenon that occurs when the Sun
is directly overhead and the shadows of vertical objects such as poles,
trees, and buildings disappear completely for a brief period of time.
Occurence:
● It
occurs when the sun’s location moves from 23.5°N to 23.5°S of Earth’s equator
and back, causing the shadow to disappear beneath objects at local noon.
What causes Uttarayan and Dakshinayan?
● The
occurrence of Uttarayan and Dakshinayan is due to the fact that the Earth’s
axis of rotation is inclined at an angle of approximately 23.5° to the axis of
revolution around the Sun.
● Uttarayan
is the movement of the Sun from south to
north from winter solstice to summer solstice, while Dakshinayan is the
back movement of the Sun from north to
south.
Uniqueness:
● It
occurs only within tropics and
absent in the temperate and polar regions.
When does a Zero Shadow Day happen?
● The
dates of Zero Shadow Day vary from place
to place, and the event is more likely to occur near the equator. This
phenomenon lasts for a small part of a second, but the effect can be seen for a
minute to a minute-and-a-half.