16 - The Universe
Q. 1. Name these :
(1)Birthplace
of stars : Huge nebulae made up of dust particles and gases.
(2) Biggest
planet in the solar system : Jupiter
(3) The
galaxy which is our neighbour : Andromeda
(4) Brightest
planet in the solar system : Venus
(5) Planet with largest number
of satellites : Jupiter.
(6) Planets without a single satellite : Mercury
and Venus.
(7) Planet with a rotation different from other
planets : Venus
(8) A celestial body that carries a tail along :
Comet
Q 2
Fill in the blanks.
Ans. (1) The group of
galaxies of which our Milky Way is a part is called Local group.
(2) Comets are made of
frozen matter and dust particles .
(3) The planet Uranus
appears as if it is rolling along its orbit.
(4) Jupiter is a stormy
planet.
(5) The Pole Star is the
best example of a variable type of star.
Q. 3. Match the columns :
Answers
(1) Galaxy – Spiral
(2) Comet -- Halley
(3)
Sun-like star - Sirius
(4)
Saturn - 33 satellites
(5)
Venus - From east to west
Q 4 Say if the
statements given below are Right or wrong. Rewrite the wrong
statements after correcting
them :
. (1) Venus is the planet closest to the sun.
Ans Wrong (Mercury is the planet closest to the
sun.)
(2) Mercury is called a stormy planet.
Ans Wrong (Jupiter is called a stormy planet.)
(3) Jupiter is the biggest planet.
Ans Right.
Q. 6. Answer the following:
(1) Which celestial bodies does a galaxy include ?
Ans. A galaxy includes
innumerable stars and their planetary systems. It has many celestial bodies
such as clusters of stars. nebulae, clouds of gases, clouds of dust. dead
stars, newly born stars, etc. The Milky Way is our galaxy in which our solar
system is included. It has planets, satellites, asteroids, dwarf planets and
meteors,
(2)
What are the types of galaxies?
Ans. The types of galaxies
are according to their shapes. These are spiral, elliptical barred spiral and
irregular.
(3) Name the
different types of stars.
Ans. There is a great
variety in stars. Some are very bright, some are faint. There are many colours
among the stars. e.g. Blue, white, yellow and reddish. Some stars have varying
brightness. Their luminance changes constantly. According to these characters,
the stars are of the following subtypes : Sun-like Stars, Red Giants Stars,
Super Nova. Binary or Twin Stars and Variable Stars.
(4) What is a special characteristic of the planet Mars ?
Ans. (1) Mars is the fourth
planet in our solar system. (2) It appears reddish as the soil on the Mars contains iron. Hence it is
also known as the red planet. (3) The highest and largest mountain in our solar
system called Olympus Mons is present on the planet
Mars. (4) Mars has two
satellites. Its rotation is in about 24 hours and it takes about 1.88
years to revolve around the sun.
(5) What are the characteristics of the planet
Neptune?
Ans (1) Neptune is the
eighth planet of our solar system. (2) One season on the Neptune planet lasts
for about 41 years. (3) The winds blow at a very high speed on Neptune. (4)
Neptune has 13 satellites. It takes approximately 16 hours and 11 minutes to
rotate around itself and 164 years for one revolution around the sun.
(6) What are the
types of comets and on what basis are they classified ?
Ans. Comets are of two
types :(1) Long period comets (2) Short period comets.
This classification is based
on the time taken by them to make a complete revolution around the sun. long period
comets take more than 200 years for a revolution while short period comets take
less than 200 years to make one revolution around the sun.
(7) What is the difference
between meteors and meteorites?
Ans (1) Meteors are rocky
pieces originating from the asteroid belt. Smaller rocky pieces are completely
burnt due to friction with air when they enter the earth's atmospheric
layers.
(2) Meteorites are the
rocky pieces that do not burn completely but fall down to the surface of the
earth.
