The Earth
in the Solar System
EXERCISES
1.
Fill in the blanks with the appropriate word.
(a) The path taken
by planets to go round the sun is called orbit.
(b) The first
known planet which has rings around it is saturn.
(c) The hottest
planet in the solar system is venus.
(d) The belt of
broken rocks and debris lying between the orbits of Mars and Jupiter is called asteroid
belt.
(e) The shape of
the moon at the beginning of the waxing phase is called new moon.
2.
Choose the correct answer.
(a) A very large
group of stars is called a
(i) galaxy (✔)
(ii)
constellation.
(iii) comet
(b) One of these
planets has many rings:
(i) Mercury
(ii) Saturn (✔)
(iii) Earth
(c) The distance
between the earth and the sun is about:
(i) 150 million km
(✔)
(ii) 76 million
km
(iii) 90 million
km
(d) The third
nearest planet to the sun is
(i) Mars
(ii) Jupiter
(iii) Earth (✔)
(e) The period
when the moon appears to become 'smaller' is called
(i) full moon
(ii) waxing
(iii) first
quarter
(iv) waning (✔)
3.
Match the rows.
|
(a) Milky Way
|
(b) Proxima
Centauri
|
(c) Ursa Minor
|
(d) Ceres
|
(e) Sol
|
|
(i) star
|
(ii)
constellation
|
(iii) dwarf
planet
|
(iv) Sun
|
(v) galaxy
|
Ans-
|
(a) Milky Way
|
(b) Proxima
Centauri
|
(c) Ursa Minor
|
(d) Ceres
|
(e) Sol
|
|
(v) galaxy
|
(i) star
|
(ii)
constellation
|
(iii) dwarf
planet
|
(iv) Sun
|
4.
Write true or false. Correct the false sentences in your notebook.
(a) Jupiter is the
largest planet of the solar system. (True)
(b) Halley's Comet
visits our solar system once every 50 years. (False)
Halley's Comet visits our solar system once
every 76 years.
(c) Saturn is the
only planet that has rings around it. (False)
Jupiter,
Saturn, Neptune and Uranus have rings around them.
(d) The moon
revolves around the earth once in 14 days. (False)
The moon revolves around the earth once in
28 days.
(e) Shooting stars
are also called comets. (False)
Shooting
stars are also called meteors.
5.
Answer the following questions in one or two sentences.
(a)
Briefly define 'universe' and 'galaxy'
Ans- Universe-
Universe is the
boundless expanse in which all matter, starts, planets, satellites, etc. exist.
Galaxy-
A galaxy is a huge
collection of gas, dust, and billions of stars and their solar systems, all
held together by gravity.
(b)
Define the term constellation. Give an example of a constellation.
Constellation-
A group of stars
that form a recognizable pattern in the sky is called constellation. For
example- Ursa Major, Ursa Monor, Orion, Hunter, Scorpio
(c)
What is the solar system?
Ans- Solar
System-
The solar system
is the name givento the sun and the group of heavenly bodies (satellites,
meteors, comets and asteroids) that revolve around it.
(d)
What according to you makes planet earth unique?
Ans- Following
factors make the planet earth unique-
1. Watery
Planet- About 3/4th of the surface of the earth is covered with water
and that is why it is also referred to as the 'watery or blue planet.
2. Oxygen- The
earth's atmosphere has an adequate amount of oxygen, which we breathe. It also
helps to maintain a suitable range of temperature on the earth.
3. Composition
of Atmosphere- All the other gases-nitrogen, carbon dioxide and some
others that are present in small amount in the atmosphere-are critical for life
on earth. For example, ozone in the atmosphere protects us from the harmful
ultraviolet rays of the sun.
4. Soil- The
land has soil that supports plant life and other living beings.
(e)
What is an asteroid?
Ans- Asteroids-
Asteroids are
small rocky bodies that lie as a belt between Mars and Jupiter.
They are probably
broken rocks and debris from an exploded planet.
They orbit around
the sun and do not have an atmosphere.
6.
Answer the following questions in four or five sentences.
(a)
How is a comet different from an asteroid?
|
Asteroid
|
Comet
|
|
Asteroids are
made up of metals and rocky material
|
comets are made
up of ice, dust and rocky material.
|
|
Asteroids are
found much closer to the Sun, where it was too warm for ices to remain solid.
|
Comets are found
farther from the Sun where ice would not melt.
Comets which
approach the Sun lose material because some of their ice melts and vaporizes
to form a tail.
|
(b)
Explain what a meteorite is.
Ans- Meteorites
are large pieces of rocks which do not burn fully and fall on the earth making
craters.
Some large rocky pieces (meteors), do
not get burnt fully in the atmosphere and fall on the earth. They form craters
on the surface. These chunks that fall on the earth are called meteorites.
(c) How
are all the gases present in the earth's atmosphere are critical for the life
on the earth?
Ans- Gases
present in the earth's atmosphere are critical for the life on the earth-
1.
Oxygen
present in the earth's atmosphere helps us breathe.
2.
Oxygen
also helps to maintain a suitable range of temperature on earth.
3.
Ozone
in the atmosphere protects us from harmful rays of the Sun.
4.
Other
gases like nitrogen carbon dioxide which are present in small amount are also
critical for life on earth.
(d) Describe
the moon.
Ans- Moon-
1.
Moon
is the earth's natural satellite.
2.
it
is 384400 km from the Earth.
3.
the
diameter of the moon is one fourth of that of the earth.
4.
the
Great moon is is one sixth of the the earth's gravity.
5.
Traces
of water and some gases have been found on the moon.
6.
conditions
on moon are unfavourable for life to exist.
7.
moon
takes about 28 days to revolve around the earth.
8.
Moon
also takes around 28 days to rotate on its own axis.
9.
surface
of the moon is full of craters due to bombardments of meteorites.
(e) Explain
the phases of moon with the help of suitable diagram.
Moon takes around
28 days to go around the earth. The shape of the Moon grows during the first
half of this period which is called the waxing period. The shape of the Moon
reduces during the other half of this period which is called the Waning period.
This is due to different positions of the Moon during its journey around the earth.
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