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9th Science > Universe > Flashcards

Universe Flashcards

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1
Q

Who proposed the heliocentric model (heltos Sun), with Sun at the centre of the solar system.

A

Nicolaus Copernicus

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2
Q

Nearly all of the matter in the universe that we understand is made of ___________, the simplest elements, created in the Big Bang

A

hydrogen and helium

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3
Q

Which galaxy is our closest neighboring galaxy

A

Andromeda

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4
Q

Our solar system is _______ away from the centre of our galaxy.

A

25,000 light years

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5
Q

Just as the Earth goes around the Sun, the Sun goes around the centre of the galaxy and it takes ______ years to do that.

A

250 million

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6
Q

_______ are the fundamental building blocks of galaxies.

A

Stars

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7
Q

The brightness of a star depends on their ___________ from the Earth

A

intensity and the distance

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8
Q

Stars also appear to be in different colours depending on their ______

A

temperature

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9
Q

Hot stars are __________ whereas cooler stars are _________ in colour.

A

white or blue,
orange or red

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10
Q

A group of stars forms an imaginary outline or meaningful pattern on the space. They represent an animal, mythological person or creature, a god, or an object. This group of stars is called

A

constellations

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11
Q

People in different cultures and countries adopted their own sets of constellation outlines. There are ______ formally accepted constellations. Aries, Gemini, Leo, Orion, Scorpius and Cassiopeia are some of the constellations.

A

88

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12
Q

Sun has hydrogen and helium of _____ ratio

A

3:1

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13
Q

The period of rotation of earth

A

23 hrs 56 mins

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14
Q

Mercury

A

58.65 days

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15
Q

Venus

A

243 days

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16
Q

Earth

A

23.93 hrs

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17
Q

Mars

A

24.62 hrs

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18
Q

Jupiter

A

9.92 hrs

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19
Q

Saturn

A

10.23 hrs

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20
Q

Uranus

A

17 hours

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21
Q

Neptune

A

18 hours

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22
Q

Farther from the Sun is the outer solar system, where the planets are much more spread out. Thus the distance between Saturn and Uranus is much ___________ than the distance between the Earth and the Mars.

A

greater (about 20 times)

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23
Q

The four planets grouped together in the inner solar system are Mercury, Venus, Earth and Mars They are called inner planets. They have a surface of solid rock crust and so are called _________,

A

terrestrial or rocky planets

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24
Q

The four large planets Jupiter, Saturn, Uranus and Neptune spread out in the outer solar system and slowly orbit the Sun are called outer planets. They are made of hydrogen, helium and other gases in huge amounts and have very dense atmosphere. They are known as __________ The four outer planets Jupiter, Saturn, Uranus and Neptune have rings whereas the four inner planets do not have any rings

A

gas giants and are called gaseous planets)

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25
Q

Mercury can be easily observed thorough ________ than naked eye

A

telescope

It always appears in the eastern horizon or western horizon of the sky

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26
Q

After our moon, it is the brightest heavenly body in our night sky. This planet spins in the opposite direction to all other planets. So, unlike Earth, the Sun rises in the west and sets in the east here.

A

Venus

Venus can be seen clearly through naked eye. It always appears in the horizon of eastern or western sky.

27
Q

Mars has two small natural satellites

A

(Deimos and Phobos).

28
Q

Jupiter is called as Giant planet. It is the largest of all planets (about _____ times larger and ______ times heavier than Earth).

A

11
318

29
Q

. It has ____ rings and _____ moons

A

3 and 65(as 2023 Jupiter has 95 moon )

30
Q

Its moon _____ is the largest moon of our solar system.

A

Ganymede

31
Q

______ appears yellowish in colour. It is the second biggest and a giant gas planet in the outer solar system.

A

Saturn

32
Q

At least ______ moons are present at saturn

A

60

33
Q

_____ is the only moon in the solar system with clouds.

A

Titan
Largest moon in saturn

34
Q

______ Having least density of all (30 times less than Earth), this planet is so light.

A

Saturn

35
Q

Uranus has the longest summers and winters each lasting ____.

A

42 years

36
Q

Neptune has _____ moons . ____ being the largest.

A

13
Triton

37
Q

_______ is the only moon in the solar system that moves in the opposite direction to the direction in which its planet spins.

A

Triton

38
Q

The biggest asteroid is ______&________ km across.

A

Ceres - 946

39
Q

________ are lumps of dust and ice that revolve around the Sun in highly elliptical orbits. Their period of revolution is very long

A

Comets

40
Q

One such comet is ________ Comet, which appears after nearly every 76 years. It was last seen in 1986. It will next be seen in 2062.

A

Halley’s

41
Q

They are small pieces of rocks scattered throughout the solar system
Most of them are burnt up by the heat generated due to friction in the Earth’s atmosphere. They are called

A

meteors

42
Q

Some of the bigger meteors may not be burnt completely and they fall on the surface of Earth These are called .

A

meteorites

43
Q

A body moving in an orbit around a planet is called .

A

satellite

44
Q

The Sun travelling at a speed of 250 km per second (9 lakh km/h) takes about 225 million years to complete one revolution around the Milky Way. This period is called a

A

cosmic year.

45
Q

The first artificial satellite Sputnik was launched in .

A

1956

46
Q

India launched its first satellite Aryabhatta on

A

April 19, 1975

47
Q

The horizontal velocity that has to be imparted to a satellite at the determined height so that it makes a circular orbit around the planet is called

A

orbital velocity.

48
Q

the satellite stays over the same spot all the time, this kind of orbit is called ‘.

A

geostationary

49
Q

Orbital velocity can be calculated using the following formula

A

v=√{(GM)/(R+h)}
G = Gravitational constant (6.673 × 10^-11 Nm^2kg-²)

M = Mass of the Earth (5.972 x 10^24 kg)

R = Radius of the Earth (6371 km)

h Height of the satellite from the surface of the Earth.

50
Q

Can you calculate the orbital velocity of a satellite orbiting at an altitude of 500 km?
Data: G=6.673 x 10-“ SI units;
M=5.972\times10^{24}kg
h=500000m
R=6371000m

A

Ans: v=7613 ms^-1 or 7.613 kms^-1

51
Q

________ is the condition in which people or objects appear to be weightless. The effects of microgravity can be seen when astronauts and objects float in space. Micro- means very small, so microgravity refers to the condition where gravity ‘seems’ to be very small.

A

Microgravity

52
Q

Time taken by a satellite to complete one revolution round the Earth is called .

A

time period
T=2πr/v

   2π(R+h)  T= -------------
  √{(GM)/(R+h)}
53
Q

At an orbital height of 500 km, find the orbital period of the satellite.

A

T= 5667 s
T=~95min

54
Q

All stars appear to us as moving from east to west, where as there is one star which appears to us stationary in its position. It has been named as Pole star. The pole star appears to us as fixed in space at the same place in the sky in the north direction

A

because it lies on the axis of rotation of the Earth which itself is fixed and does not change its position in space. It may be noted that the pole star is not visible from the southern hemisphere.

55
Q

Kepler was able to summarize the carefully collected data of his mentor,

A

Tycho Brahe

56
Q

Kepler First Law - The Law of Ellipses

A

All planets revolve around the Sun in elliptical orbits with Sun at one of their foci.

57
Q

Second Law - The Law of Equal Areas

A

The line connecting the planet and the Sun covers equal areas in equal intervals of time

58
Q

Third Law - The Law of Harmonies

A

The square of time period of revolution of a planet around the Sun is directly proportional to the cube of the distance between sun and the planets.

59
Q

As great as the ISS’ scientific achievements are, no less in accomplishment is the international co-operation which resulted in the construction of the ISS. An international collaboration of five different space agencies of 16 countries provides, maintains and operates the ISS. They are: _________ are also part of the consortium.

A

NASA (USA), Roskosmos (Russia), ESA (Europe), JAXA (Japan) and CSA (Cananda). Belgium, Brazil, Denmark, France, Germany, Italy, Holland, Norway, Spain, Sweden, Switzerland and the UK

60
Q

The period of revolution of planet A around the Sun is 8 times that of planet B. How many times is the distance of planet A as great as that of planet B?

A

4

61
Q

The Big Bang occurred ______years ago.

A

(a) 13.7 billion

62
Q

The speed of Sun in km/s is

A

250 km/s

63
Q

The rotational period of the Sun near its poles is

A

36 days

64
Q
  1. The third law of Kepler is also known as the Law of
A

Harmonics

9th Science (19 decks)

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