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Planets of the solar system - class-VII

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The time interval between two successive noon when sun passes through zenith point (meridian) is known as

  1. sidereal day

  2. mean solar day

  3. solar year

  4. lunar month


Correct Option: B
Explanation:

Mean solar day is the time interval between two successive noon when sun passes through zenith point (meridian).

Light from the sun reaches the earth approximately in

  1. 5 s

  2. 50 s

  3. 500 s

  4. 0.5 s


Correct Option: C
Explanation:

Time taken by light to reach the earth from the sun is, 

$t= 8 min 20 s= 8 \times 60s + 20 s $
$= 480s+ 20s = 500s$

State whether the sentences is true(T) or false(F).
Saptarishi and Ursa Major are two different constellations.

  1. True

  2. False


Correct Option: B
Explanation:

Ursa Major constellation lies in the northern sky. Its name means “the great bear,” or “the larger bear,” in Latin. The smaller bear is represented by Ursa Minor. Its brightest stars form the Big Dipper asterism, one of the most recognizable shapes in the sky, also known as the Plough.

Ursa Major is called as Saptarishi as it has seven prominent stars.

 

Mark the odd one in the following list.

  1. Earth

  2. Jupiter

  3. Sun

  4. Saturn

  5. Venus


Correct Option: C
Explanation:
  • Sun is star, which emits light from its own sources of energy. Remaining options Earth, Jupiter,Saturn and Venus are planets that revolve around the Sun and shine by the light of Sun.
  • Hence, Sun is the odd one in given options.

Galileo's observations that venus shows all  of the phases, was important because, it discredited?

  1. Newtons law of gravitation.

  2. The Copernican theory

  3. Keplers Harmonic Law

  4. The Ptolemaic Theory


Correct Option: D

All the planets in the solar system revolve around the Sun in same plane. This statement is

  1. True

  2. False


Correct Option: A
Explanation:

Most of the planets orbit the Sun very near the same plane in which the Earth orbits, the ecliptic.
The orbits of the planets are ellipses with the Sun at one focus, though all except Mercury are very nearly circular. The orbits of the planets are all more or less in the same plane (called the ecliptic and defined by the plane of the Earth's orbit). The ecliptic is inclined only 7 degrees from the plane of the Sun's equator.
Hence, the statement is true.

What is the time taken by the Jupiter to go around the Sun?

  1. 21 years

  2. 20 years

  3. 12 years

  4. 2 years


Correct Option: C
Explanation:

Jupiter revolves or orbits around the Sun once every 11.86 Earth years, or once every 4,330.6 Earth days. Jupiter travels at an average speed of 29,236 miles per hour or 47,051 km per hour in its orbit around the Sun.
Hence, the planet Jupiter takes 12 years to go around the Sun.

The distance between the sun and the earth is

  1. 150 million kilometers

  2. 100 million kilometers

  3. 2 billion kilometers

  4. 1.2 light years


Correct Option: A
Explanation:

The distance between the sun and the earth is $149,600,000 km$ which is approximately equal to $150$ million kilometers.

Who is regarded chief of solar system? 

  1. Sun

  2. Moon

  3. Earth

  4. Sky


Correct Option: A
Explanation:

Sun is regarded as the chief of solar system. It is because all of the other planets circle around it due to the gravitational pull because of its enormous mass.

The mean distance between the Earth and Sun as well as the distances within the solar system is represented by

  1. light year

  2. astronomical units

  3. parsec

  4. Angstrom


Correct Option: B
Explanation:

The mean distance between the Earth and Sun as well as the distances within the solar system is represented by astronomical units.
One astronomical unit (AU) represents:
1 AU = 149,597,870.700 kilometers (or 149,597,870,700 meters)
An astronomical unit is the mean distance between the Earth and the Sun.

Match items in column A with one or more items in column B 

Column A Column B
(i) Inner planet  (a) Saturn 
(ii) Outer planet  (b) Pole star 
(iii) Constellation (c) Great Bear
(iv) Satellite of the earth  (d) Moon
(e) Earth 
(f) Orion 
(g) Mars 
  1. $( i) - g,e    \  (ii) - a \ (iii)   -c,f  (iv) - d$

  2. $( i) - g,e    \  (ii) - c,f \ (iii)   -a  (iv) - d$

  3. $( i) - a    \  (ii) - b \ (iii)   -c,f  (iv) - d$

  4. None of these


Correct Option: A
Explanation:
Column A Column B
(i) Inner planet  (g), (e) Mars, Earth 
(ii) Outer planet  (a) Saturn 
(iii) Constellation  (c), (f) Great bear, Orion 
(iv) Satellite of the Earth  (d) Moon

Which of the following planets takes minimum time to take one revolution around the Sun?

  1. Mercury

  2. Jupiter

  3. Saturn

  4. Pluto


Correct Option: A
Explanation:

Out of these fours mercury takes minimum time to revolute one round. It takes $88$ days to do so.

Day and night are caused by ___________.

  1. revolution of the earth

  2. rotation of the earth

  3. both rotation and revolution of the earth

  4. neither rotation nor revolution of the earth


Correct Option: B
Explanation:

Day and night are caused by  rotation of earth.

Ans: rotation of earth

The planet Uranus rotates on its axis from

  1. east to west

  2. west to east

  3. north to south

  4. south to north


Correct Option: A
Explanation:

Every planet in solar system except venus and uranus rotates frm west to east so uranus rotates from east to west.

Because of its highly tilted axis, ________ appears to roll along the orbital plane.
  1. Uranus

  2. Mercury

  3. Saturn

  4. Venus


Correct Option: A
Explanation:

A unique feature of Uranus is that it appears to roll along its orbital plane. This is because it has a highly tilted axis which makes it almost parallel to its orbital motion and the planet appears to roll.

________ is the fastest rotating planet.
  1. Saturn

  2. Jupiter

  3. Uranus

  4. Earth


Correct Option: B
Explanation:

Jupiter is the fastest rotating planet. It take only 9 hours and 55 min to complete one rotation about its own axis.

On which two days does the Sun rise exactly in the East?

  1. April 21, July 23

  2. March 21, September 23

  3. March 23, September 21

  4. June 21, December 22


Correct Option: B
Explanation:

From summer solstice (June 21), the Sun starts moving towards the South and from winter solstice (December 22), the Sun starts moving towards North. So during summer solstice, it is in the south eastern part and in winter solstice it is in the north eastern part. However, there are 2 days, i.e., March 21 and September 23, when the Sun rises exactly in the East.

_________ stated that Sun was the centre of our universe and not Earth.
  1. Albert Einstein

  2. Isaac Newton

  3. Nicolaus Coppernicus

  4. Galileo Galilei


Correct Option: C
Explanation:

With the development of the heliocentric model by Nicolaus Copernicus in the 16th century, the sun was believed to be the center of the Universe, with the planets (including Earth) and stars orbiting it. 

Planets do not collide with each other because

  1. those are of different sizes

  2. those have fixed, non-intersecting individual orbits

  3. those rotate from West to East

  4. each planet has a different time of rotation and revolution


Correct Option: B
Explanation:

Every planet is at a different distance from the Sun and has a fixed orbit in which it revolves around the Sun. The Sun"s gravitational force holds the planets in this place and they do not collide with each other as their orbits are non-intersecting.

The time taken by a planet for one complete revolution changes according to:
  1. its distance from the Sun

  2. its size

  3. its mass

  4. the shape of its orbit


Correct Option: A
Explanation:

As the distance between the Sun and the planet increases, the time taken by the planet to complete one revolution around the Sun also increases as the planet has to cover more distance as compared to the planets before it.

Why does Venus show phases like the moon?

  1. It rotates from East to West

  2. It is covered by clouds

  3. Its atmosphere is dense

  4. None of the above


Correct Option: A
Explanation:

Just like moon, Venus too rotates from East to West. Thus, only that part of Venus is visible to us which reflects the light from the Sun towards us. Hence, the Venus appears to show phases because the Earth and Venus rotate in opposite direction.

Autumnal Equinox occurs on ?

  1. September 22

  2. September 23

  3. October 22

  4. October 23


Correct Option: B

Degenerate electron pressure will not be sufficient to prevent the core collapse of white dwarf if its mass becomes n times of our solar mass. Value of n is:

  1. 0.5

  2. 0.8

  3. 1

  4. 1.4


Correct Option: D
Explanation:

This is the definition of Chandrasekhar's Limit . 
Degenerate electron pressure will not be sufficient to prevent core collapse of white dwarf if its mass becomes 1.4 times or more of our solar mass.

The planets keep changing their position with respect to:

  1. Galaxy

  2. Stars

  3. Venus

  4. Moon


Correct Option: B
Explanation:

Planets are solid heavenly bodies which revolve around the Sun in closed elliptical paths. A planet is made of rock and metal and produces no light of its own. A planet shines because it reflects the light of the Sun. Since, the planets are much nearer to the stars, they appear to be big and do not twinkle at night. The planets move around the Sun from West to East, so the relative positions of the planets keep changing day by day. They are very small compared to the sun and other stars. 
Hence, the star appears to remain in a fixed position with respect to each other whereas the distance between the planets keep changing constantly.

The planets do not emit light of their own. This statement is:

  1. True

  2. False


Correct Option: A
Explanation:

Planets are solid heavenly bodies which revolve around the Sun in a closed elliptical paths. A planet is made of rock and metal and produces no light of its own. A planet shines because it reflects the light of the Sun. Since, the planets are much nearer to the stars, they appear to be big and do not twinkle at night.
Hence, the statement is true.

Which of the following statement is incorrect?

  1. Planet jupiter shows phases like Moon

  2. The axis of rotation of Earth is slightly tilted with respect to the plane of its orbit around the Sun

  3. Diameter of Jupiter is about 11 times the diameter of the Earth

  4. Planet Uranus is made up mainly helium and nitrogen gases


Correct Option: A

Which of the following is a proof of the Earth's revolution around the Sun? 

  1. Rising and setting of the Sun

  2. The Foucault pendulum experiment

  3. Parallax of stars

  4. Seasons


Correct Option: D

The earth revolves about the sun in an elliptical orbit with mean radius $9.3 \times 10^7\ m$ in a period of $1$ year. Assuming that there are no outside influences, then

  1. The earth's kinetic energy remains constant.

  2. The earth's angular momentum remains constant.

  3. The earth's potential energy remains constant.

  4. All the statements above are correct.


Correct Option: C

Earth is revolving around the sun.If the distance of earth from the sun is reduced to $\frac { 1 } { 4 } \mathrm { th }$ of the present distance, then the length of present day will be reduced by 

  1. 1 / 4

  2. 1 / 2

  3. 1 / 8

  4. 1 / 6


Correct Option: A

The mass of a planet Jupiter is $1.9 \times 10^{27} kg$ and that of the Sun is $1.99 \times 10^{30} kg$. The mean distance of the Sun from Jupiter is $7.8 \times 10^{11} m$. The gravitational force, which the Sun exerts on Jupiter is.

  1. $4.1 \times 10^{23} N$

  2. $4.1 \times 10^{34} N$

  3. $2.2 \times 10^{23} N$

  4. $2.2 \times 10^{34} N$


Correct Option: A

Two plates move around the Sun. The periodic times and the mean radii of the orbits are $T _1, T _2$ and $r _1, r _2$ respectively. The ratio $\dfrac{T _1}{T _2}$ is equal to.

  1. $\left (\dfrac{r _1}{r _2} \right)^{\dfrac{1}{2}}$

  2. $\left (\dfrac{r _1}{r _2} \right)$

  3. $\left (\dfrac{r _1}{r _2} \right)^{2}$

  4. $\left (\dfrac{r _1}{r _2} \right)^{\dfrac{3}{2}}$


Correct Option: D

As per modern classification of solar system, number of planets excluding Earth is: 

  1. $7$

  2. $8$

  3. $9$

  4. $10$


Correct Option: A
Explanation:
As per older convention, there used to be $9$ planets in total in the solar system. As per modern convention, Pluto is no more a planet. So, excluding Earth, there are $7$ planets in total.

The radius of Jupiter is 11 times the radius of the Earth. Calculate the ratio of the volumes of Jupiter and the Earth. How many Earths can Jupiter accommodate ? 

  1. 1331

  2. 1221

  3. 111

  4. None of these


Correct Option: A
Explanation:

Planets are like spheres. Volume of a sphere is given by, 
V = $\displaystyle{\frac{4}{3}\pi r^3}$ 
Let the r$ _1$, r$ _2$ be radii of the Jupiter and the Earth respectively. 
r$ _1$ $= 11r _2$ _(1)
Volume of Jupiter, V$ _1$ = $\displaystyle{\frac{4}{3}\pi r^3 _1}$ _(2) 
Volume of Earth, V$ _2$ = $\displaystyle{\frac{4}{3}\pi r^3 _2}$ _(3) 
$\displaystyle{\frac{(2)}{(3)} \Rightarrow \frac{V _1}{V _2} = \frac{\frac{4}{3}\pi r _1^3}{\frac{4}{3} \pi r _2^3} = \frac{r _1^3}{r _2^3}}$ 
$\displaystyle{\frac{V _1}{V _2} = \frac{r _1^3}{r _2^3} = \frac{(11r _2)^3}{r _2^3} = (11)^3}$ = 1331 
Jupiter can accommodate 1331 number of Earths within it.

The earth spins about its axis from

  1. west to east

  2. east to west

  3. north to south

  4. south to north


Correct Option: A
Explanation:

Earth spins about its own axis from west to east. In another word earth turns counter clockwise direction as viewed from north pole.

The mean distance between Earth and Sun is referred to as one

  1. light year

  2. fermi

  3. astronomical unit

  4. angstrom


Correct Option: C
Explanation:

On Astronomical unit is the mean distance between earth and sun.

Days and nights are caused by

  1. rotation of the Earth

  2. revolution of the Earth

  3. both rotation and revolution of the Earth

  4. neither rotation nor revolution of the Earth


Correct Option: A
Explanation:

As earth is rotating on its own axis so its half part is exposed to sun cause day at that part and hidden half part suffers from darkness called night.

All the stars appear to move from

  1. west to east

  2. east to west

  3. north to south

  4. south to north


Correct Option: B
Explanation:

As earth is rotating on its own axis from west to east so, due to relative motion star appears to move from east to west.

The planet which shows retrograde motion is

  1. Venus

  2. Mercury

  3. Jupiter

  4. Mars


Correct Option: A
Explanation:

Ans : Venus

The planet Jupiter is bulged at the centre and flattened at the poles because of ___________.

  1. movement of gases

  2. heaviness of the planet

  3. rotation of the planet

  4. revolution of the planet


Correct Option: C

Which of the following planets takes maximum time to complete one revolution around the Sun?

  1. Mercury

  2. Jupiter

  3. Saturn

  4. Neptune


Correct Option: D
Explanation:

Neptune takes maximum time to complete one revolution as it is the farthest planet.

Ans: Neptune

The planets revolve round the sun in _______ orbits.

  1. circular

  2. spiral

  3. elliptical

  4. helical


Correct Option: C
Explanation:

Ans: Elliptical 

The difference in the length of a mean solar day and a sidereal day is about

  1. $1$ minute

  2. $4$ minute

  3. $15$ minute

  4. $56$ minute


Correct Option: B
Explanation:

Solar day is the time taken by earth to complete one rotation about its axis with respect to sun. Sidereal day is the time taken by earth to complete one rotation about its axis with respect to distant star. There is a difference of $4$ minutes between solar day and sidereal day. Solar day is longer as earth has to rotate greater angle to attain same position with respect to sun due to its own motion (revolution) round the sun. Its position with respect to distant star remains almost fixed.

Which is the correct sequence of planets in increasing order of size?

  1. Saturn, Jupitar, Uranus, Neptune

  2. Jupitar, Saturn, Uranus, Neptune

  3. Jupitar, Uranus, Neptune, Saturn

  4. Neptune, Uranus, Saturn, Jupitar


Correct Option: B
Explanation:

A star and all the objects travelling around it — planets, moons, asteroids, comets and meteoroids constitute a solar system. Our solar system is located in Milky Way galaxy. Sun is the star of our solar system. The eight planets and their natural satellites, dwarf planets and their satellites, as well as asteroids, comets and other celestial bodies revolve around the sun.

Order of the planets of solar system on the basis of their size is given as following: -

  1. Jupiter - Its diameter is 69,911 km.
  2. Saturn - Its diameter is 58,232 km.
  3. Uranus - Its diameter is 25,362 km.
  4. Neptune - Its diameter is 24,622 km.
  5. Earth - Its diameter is 6,371 km.
  6. Venus- Its diameter is 6,052 km.
  7. Mars - Its diameter is 3,390 km.
  8. Mercury- Its diameter is 2,440 km.

If the axis of rotation of the earth were extended into space then it would pass close to

  1. The moon

  2. The sun

  3. The polar star

  4. The centre of mass of all the planets in the solar system


Correct Option: C
Explanation:

A pole star is a visible star, which lies approximately directly overhead when viewed from earth's north pole or south pole. In practice the term pole star usually refers to polars, which is the current northern pole star, also known as north star. The south celestial pole lacks a bright star like polarise to mark its position.

Which of the following describes ecliptic orbit?

  1. Orbit travelled by the Moon round the Sun.

  2. Path travelled by the Earth round the Sun

  3. Orbit along which Sun appears to move among the stars

  4. Orbit along which Moon appears to move among the stars


Correct Option: C
Explanation:
An ecliptic orbit is the one, in which the Sun appears to move among all the stars.

What is Minor Planet?

  1. Term used to describe an astronomical object that is neither a dominant planet nor a comet

  2. It includes away planet that orbits around the sun

  3. Both A and B

  4. None of the above


Correct Option: C
Explanation:

Minor planet is a term used to refer to a celestial object – that is not a planet or comet – which orbits the Sun. Found in 1801, Ceres, also known as a dwarf planet, was the first minor planet discovered. 

Who was the first to suggest, "A planet moves most quickly when it is closest to the sun, but slows down as it moves farther away"?

  1. Johannes Kepler

  2. Galileo Galilei

  3. Tycho Brahe

  4. Edwin Hubble


Correct Option: A
Explanation:

Kepler's law states that a line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time. So a planet moves most quickly when it is closest to the sun,as it have to cover more distance in same time but it again  slows down as it moves farther away as covering distance is less.

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