Page 113 - SST Class 06

Just Think! Info Bits
Info Bits

Suman throws a lavish party on each of her As the region from the North Pole to the Arctic
birthday and last time she did so was on 29 Circle receives sunlight continuously for 24 hours,
February, 2016; when will she throw her next the phenomenon of midnight sun occurs in the
party? countries of Norway and Sweden.

Winter Solstice
The Earth takes about 365 days and 6 hours to
complete one revolution around the Sun. So, we The longest night in the Northern Hemisphere
have 365 days in a year. The additional 6 hours occurs on 22 December because this receives
are added over four years to make one day and sunlight for the shortest duration. On this day, the
this day is added to the leap year. Thus all years Sun shines vertically over the Tropic of Capricorn
which can be divided by 4 are leap years. The (23½°S). It is winter in this hemisphere and this
month of February has 28 days, but in a leap year, situation is called the winter solstice.
it has 29 days.
Spring/Vernal Northern spring,
Equinox Southern autumn
Seasons
Summer Winter
The Earth rotates west to east. It also revolves Solstice 21 March Solstice
round the Sun west to east. These two motions
21 June SUN 22 December
together are responsible for the change of seasons.
As the Earth goes round the Sun in its elliptical Northern summer, 23 September Southern summer
Northern winter,
Southern winter
orbit, one hemisphere receives more sunlight than
the other. When the Northern Hemisphere faces
Autumn Northern autumn,
Equinox Southern spring
the Sun, it receives sunlight for a longer duration
and it results in summer in this hemisphere. It Earth’s revolution and seasons
results in longer dark hours in the Southern Quiz Time
Hemisphere resulting in winter there.
Write True or False :
When the Earth on its journey brings the other
hemisphere in sunlight, the above phenomenon is 1. The Earth rotates from east to west. _____
reversed. That is, when the Southern Hemisphere 2. The longest day in the Northern Hemisphere
faces the Sun, the summer occurs there and the occurs on 21 June. _____
Northern Hemisphere experiences winter. 3. The Earth takes about 365 days and 8 hours to

The Earth has four chief positions in the cycle of complete one revolution around the Sun. _____
its revolution, as a result of which it has four 4. On 21 June, the Sun shines vertically over the
seasons—spring, summer, autumn and winter. The Tropic of Cancer (23½°N). _____
four positions of the Earth in relation to the Sun
are assumed on 21 June, 23 September, 22 5. The Earth has five chief positions in the cycle of
its revolution. _____
December and 21 March.
Equinox
Summer Solstice
On 21 March and 23 September, the Sun shines
The longest day in the Northern Hemisphere
vertically over the Equator. None of the poles is
occurs on 21 June because this receives sunlight
tilted towards the Sun on these days. As a result,
for the longest duration. On this day, the Sun
shines vertically over the Tropic of Cancer the days and nights are of equal duration
throughout the Earth. This situation is called the
(23½°N). It is summer in this hemisphere and this
situation is called the summer solstice. equinox. On 23 September, the autumn season
occurs in the Northern Hemisphere and the spring
Motions of the Earth
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