The Solar System
I] Define/Explain:
a) BIG
BANG THEORY: It is believed that the universe was formed 15 billion years ago
due to a cosmic explosion, called big bang. And it is still expanding.
b) NEBULA:
The big bang explosion led to the formation of giant clouds of gases and dust
particles called nebula.
c) CELESTIAL
BODY: Bodies present in space are called heavenly or celestial bodies.
d) CONSTELLATIONS:
Clusters or group of stars are called Constellations. E.g. URSA MAJOR, ORION,
TAURAS, CANIS MAJOR, LEO etc.
e) GALAXY:
When stars are found in very large clusters or groups, the clusters are called
galaxies.
f) ECPLISE:
The Sun being a luminous body casts a shadow of the opaque body-the moon and
the earth. Formation of such a shadow is known as an eclipse. There are two
types of eclipses- The solar eclipses and lunar eclipse.
II] Give one-word:
a) Twinkling
spots of lights in the sky – STARS
b) The
major galaxy closest to our earth- ANDROMEDA
c) Shape
of Andromeda galaxy- SPIRAL
d) The
great bear – URSA MAJOR
e) Age
of the sun- 5 BILLION YEARS OLD
f) Two
main gases present in the sun- HYDORGEN AND HELIUM
g) We
live in _MILKY WAY galaxy.
h) Name
of the 10th planet- ERIS
i)
Shape of the earth- GEOID
j)
Name of brightest planet-VENUS
k) Name
of hottest planet-MERCURY
l)
Sideways planet- URANUS
m) Coldest
planet-NEPTUNE
n) Other
name of new moon day-AMAVASYA
III] Give answer to following questions in short.
a)
What
is photosphere?
Ans - This is the outer layer of
the Sun that is visible to us. This is where the light we see from the Sun
originates.
b)
How
much time light takes to reach earth from the sun?
Ans – The light from the sun
reaches the Earth in about 8 minutes and 20 seconds.
c)
What
do you mean by Planet day?
Ans – One rotation of the planet on
its own axis is completed in the time period of one planet day.
d)
Do
gas giants have rocks too?
Ans – They have very small rocky
cores.
e)
How
much time moon takes to revolve around the earth?
Ans – The moon completes one
revolution around the Earth in 27 days and 8 hours.
f)
When
will the Halley’s Comet be seen again?
Ans – It was last seen in 1986 and
it appears after every 76 years. So, it will be seen now in 2062.
IV]
Give answers in detail:
a)
Briefly
explain why earth is suitable for life to exist.
Ans – The favourable conditions
that facilitate life on the Earth are as follows:
1) Atmosphere
that surrounds the Earth.
2) Moderate
temperature
3) Ozone
layer in the atmosphere that protects living things from harmful ultraviolet
radiations coming from the Sun.
4) Presence
of adequate amount of fresh water.
5) Suitable
seasons and weather conditions.
b)
Write
down points of differences between Stars and Planets.
Ans.-
Stars
|
Planets
|
|
1
|
Self – luminous bodies. They emit
their own light and heat.
|
Non- luminous bodies. They only
reflect the light received from the Sun.
|
2
|
Made up of hot and burning gases.
|
Made up of solid materials.
|
3
|
Very large in size.
|
Comparatively smaller in size.
|
4
|
Move around the centre of the galaxy.
|
Move around a star, the Sun
|
c)
If
moon is revolving around the sun, then why do we see same side of the moon from
the surface of the earth?
Ans – The time taken by the Moon to
rotate on its axis is same as of its revolution around the Earth( 27 days 8
hour) so, we always see the same side of the Moon from the Earth.
d)
Draw
a diagram showing different phases of moon and explain briefly about each of
these phases.
Ans - Phases of the moon: different
shapes and sizes of the moon visible at night
during the month
Waxing: growing period of the
moon
Waning: shrinking period of the
moon
Crescent phase (waxing):: first
visible phase
First Quarter Phase (waxing): :
the phase after the crescent phase
Gibbous phase (waxing): the phase
between the first quarter and the full moon
Full moon: when the moon appears
full in the sky
Then onwards, the moon starts
disappearing passing through waning gibbous and crescent phase.
New moon day is when moon does not
receive sunlight and we are not able to see the moon.
e)
What
is the difference between meteors, asteroids, meteorites and meteoroids?
Ans – Asteroids – also known as planetoids
small celestial bodies similar to
planets
revolve around the sun in an
elliptical orbit
lie between the orbits of Mars
and Jupiter
this region is called the
asteroid belt.
Meteoroids – these are pieces of
rocks moving with high speed around the Sun.
Meteors – When meteoroids come near
the Earth, they are pulled by gravity. On entering the Earth’s atmosphere they
produce heat and light and are known as meteors or shooting stars.
Meteorites – Meteors fall on the
Earth’s surface causing huge dents or craters. These rock fragments are called
meteorites.
f)
What
is the difference between a comet and shooting stars?
Ans – Comets are huge lumps made up
of snow and rocky dust which follows its own elliptical orbit around the sun.
Shooting stars are meteoroids which
produce light when they enter in the Earth’s atmosphere.
Draw the phases of the moon
Draw the solar system
Draw the phases of the moon
Draw the solar system
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