Page 149 - Innovator's Science-8

• Find the duration of the solar day by finding a difference in time on two
consecutive days as shown in the first column. Fill in the other enteries

on your own.
Finding the dura on of a solar day
Date Time of shortest shadow (hh:mm) Dura on of day (hh:mm)

22 March 2025 12:20 ______
23 March 2025 12:20 ______

24 March 2025 ______ ______

Calculate the average duration of the day. Is it almost equal to 24 hours?
The phases of the Moon create a
Cycle of Moon's phases due to natural cycle that lasts longer than a
its revolution around the Earth
defines a month day. It takes about 29.5 days, or
almost a month, for the Moon to go
through all its phases, from new

Moon to full Moon and back again.
Cycle of Sun returning to its This cycle of the Moon's phases is
highest position in the sky due
Cycle of Earth's seasons due to Earth's rotation defines a day the reason we measure a month as
to its revolution around the a unit of time. The next bigger unit
Sun define a year
of time is the year, which is based
The Earth goes around the Sun, and the Moon revolves
around the Earth in regular intervals of time. on the Earth's movement around
the Sun. The Earth takes about 365
and a quarter days to complete one full orbit around the Sun. During this

time, Earth experiences different seasons, and this cycle of seasons helps
us define a solar year .

LUNAR CALENDARS

In ancient times, people noticed that in one full cycle of seasons, about 12
cycles of the Moon's phases could fit in. This means there were roughly 12
lunar months in a year. Because of this, people created lunar calendars
based on the Moon's phases. In these calendars, the day is the shortest unit

of time, a month lasts about 29.5 days, and a lunar year is made up of 12
lunar months. So, the Moon's phases helped people measure longer
periods of time and organize their calendars.The Sun appears to rise in the

east and set in the west every day because the Earth rotates around its axis.
This rotation makes the Sun seem to move across the sky in a regular cycle,
which we call a day. The time the Sun takes to go from its highest point in
the sky one day to the same point the next day is about 24 hours, known as
a mean solar day . We can tell when the Sun is at its highest by looking at

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Science-8