Universe And Space Book Back Questions 7th Science Lesson 15

7th Science Lesson 15

15] Universe And Space

Book Back Questions with Answer and Do You Know Box Content

Do You Know?

Astronomical unit: The average distance between the Earth and the Sun is called an astronomical unit. It is denoted by ‘au’. 1 au = 1.496 x 10⁸ km

Light year: The distance travelled by light in one year is called a light year. It is denoted by ‘ly’. 1 ly = 9.4607 x 10¹² km

Parsec: A parsec is defined as the distance at which one astronomical unit subtends an angle of one arc second. It is denoted by ‘pc’. 1 pc = 3.2615 ly = 3.09 x 10¹³ km

The Hubble Space Telescope and powerful ground-based telescopes are now beginning to find galaxies that were created about one billion years after the Big Bang. These small galaxies were much closer together than galaxies are today. Collisions were common. Like two flames moving towards each other, they merged into bigger galaxies. Our Milky Way galaxy came together in this way.

Subrahmanyan Chandrasekhar (19 October 1910 – 21 August 1995) was an Indian American astrophysicist who spent his professional life in the United States. He was awarded the 1983 Nobel Prize for Physics with William A Fowler. His mathematical treatment of stellar evolution yielded many of the best current theoretical models of the later evolutionary stages of massive stars and black holes. The Chandrasekhar limit is named after him. Chandrasekhar worked on a wide variety of physical problems in his lifetime.

In 1989, Galileo Galilei was memorialized with the launch of a Jupiter-bound space probe bearing his name. During its 14-years voyage, the Galileo space probe and its detachable mini-probe, visited Venus, the asteroid Gaspra, observed the impact of Comet Shoemaker-Levy 9 on Jupiter, Europa, Callisto, IO and Amalthea. In order to avoid the possible contamination of one of Jupiter’s moons, the Galileo space probe was purposely crashed into Jupiter at the end of its mission in September 2003.

Choose the best answers:

1. The moon takes ____________ days to complete one revolution around the Earth.

(a) 25

(b) 26

(c) 27

(d) 28

2. If the Moon is appearing in the sky today near the star Karthikai, the position of the Moon after 27 days is near the star

(a) Bharani

(b) Karthikai

(c) Rohini

(d) Asvini

3. Telescope was invented by

(a) Han Lippershey

(b) Galilio

(c) Nicolus Copernicus

(d) Ptolemy

4. The galaxy containing young and hot stars is

(a) Elliptical galaxy

(b) Irregular galaxy

(c) Cluster

(d) Spiral galaxy

5. With the launch of this satellite, ISRO became capable of launching 4 ton heavy satellites.

(a) GSAT – 13

(b) GSAT – 14

(c) GSAT – 17

(d) Way par GSAT – 19

Fill in the blanks:

1. Waxing of moon means ____________

2. Heliocentric model is proposed by _______________

3. ______________ is the prevailing model of Evolution of the Universe.

4. ______________ is a large constellation which covers a large part of the sky.

5. ______________ is the first satellite launched by India.

State true or false. If false, correct the statement:

1. On a full moon day, when the Sun is setting in the west, moon rises in the West.

2. The word crescent refers to the phases where the moon is less than half illuminated.

3. Galilio accepted the Geo-centric model.

4. Our Milky Way galaxy is identified as an elliptical galaxy.

5. The planet Venus in our solar system doesn’t have a moon.

Match the following:

1. Rohini – GSLV – Mark III

2. GSAT – 14 – GSLV Mark III m1

3. GSAT – 19 – SLV – 3

4. Chandrayaan – 2 – PSLV – XL C25

5. Mangalyaan – GSLV – D5

Complete the analogy:

1. Older stars: elliptical galaxies: younger stars: ______________

2. Nearest galaxy: Andromeda: Nearest star: ______________

Very short answers:

1. The word ______________ refers to the phases where the moon is less than half illuminated (crescent/gibbous)

2. _______________ and _________________ planets never appear in the mid-night sky.

3. Number of days taken by the Mars to orbit around the Sun.

4. In which phase does the size of the planet Venus is small?

5. The only evidence of the big bang theory is.

6. The galaxy which contains abundant amount of gas and dust is _______________

7. Which country launched the world’s first artificial launch vehicle?

Answers:

Choose the best answers:

1. 27 2. Karthikai 3. Han Lippershey 4. Spiral galaxy 5. Way par GSAT-19

Fill in the blanks:

1. Changing of Full Moon 2. Nicolaus Copernicus 3. Big bang theory 4. Ursa Major 5. Aryabhatta

Say True or False:

1. False

Correct Statement: On a full moon day when the Sun is setting in the west, the moon rises at the same time in the east.

2. True

3. False

Correct Statement: Galilio accepted the Sun-heliocentric theory of Copernicus.

4. False

Correct Statement: Our Milky Way galaxy is identified as a Spiral galaxy.

5. True

Match the following:

1. SLV-3 2. PSLV-XL C25 3. GSLV-Mark III 4. GSLV-D5 5. GSLV Mark III m1

Complete the Analogy:

1. Spiral galaxies 2. Proxima Centauri

Very Short Answers:

1. Crescent 2. Venus and Mercury 3. 687 days 4. Gibbous phase 5. Hubble’s discovery

6. Spiral galaxy 7. The Soviet Union