The Universe Part-2

31. Which one of the following Stars is nearest to the Earth? [I.A.S. (Pre) 1997]

(a) Polaris
(b) Alpha Centauri
(c) Sun
(d) Sirius

Correct Answer: (c) Sun

Solution:The Sun is the closest star to the Earth, about 149.6 × 106 kilometer away. Polaris is at a distance of 434 Light years (New estimate 323 light years) from the Earth while Sirius A is at a distance of 8.6 Light years from Earth. Alpha Centauri is the nearest neighbour after sun, with a distance of 4.35 light year from the Earth.

32. In completing one revolution of the sun, Earth takes approximately - [4st B.P.S.C. (Pre) 1996]

(a) 365 days
(b) 365.25 days
(c) 365.5 days
(d) 365.75 days

Correct Answer: (b) 365.25 days

Solution:The Earth takes 365.25636 days or 365 days, 6 hours, 9 minutes and 9.51 second to complete orbit revolution the Sun. This period is known as 'Solar year'. The solar year is also known as The tropical year. The tropical year is equal to 365.24 days. In the year 2000, the increase of 5 Minute had been noted in comparison to other years. In this period the time was calculated to 365 days, 6 hours, 13 minutes (in place of 9 minutes), 53.26 second (in place of 9.51 second). Such year is known as 'Anomalistic Year'.

33. The planet nearest to the Earth is - [U.P.P.C.S. (Pre) 1991, U.P.P.C.S. (Pre) 1993, U.P.P.C.S. (Pre) 1997, Uttarakhand P.C.S. (Pre) 2002, U.P.P.C.S. (Pre) 2012]

(a) Venus
(b) Mercury
(c) Mars
(d) Jupiter

Correct Answer: (a) Venus

Solution:The Earth takes 365.25636 days or 365 days, 6 hours, 9 minutes and 9.51 second to complete orbit revolution the Sun. This period is known as 'Solar year'. The solar year is also known as The tropical year. The tropical year is equal to 365.24 days. In the year 2000, the increase of 5 Minute had been noted in comparison to other years. In this period the time was calculated to 365 days, 6 hours, 13 minutes (in place of 9 minutes), 53.26 second (in place of 9.51 second). Such year is known as 'Anomalistic Year'.

34. Approximately how much distance per minute does earth cover while revolving? [44th B.P.S.C. (Pre) 2001]

Correct Answer: (e) None of the above

Solution:Earth's equatorial perimeter is about 40,090.28 km. This distance is covered by Earth in 24 hours and this indicates that cruising speed of Earth on its axis per hour is 40,090.28 km/ 24 hour = 1670 km/ hour (approx). According to this calculation the cruising speed per minute is = 1670 km/60 min = 27.8 km/ min. Thus, none of the given answers is correct, Note In this question rotating should be on the place of revolving.

35. The equatorial circumference of the Earth is nearly [Uttarakhand P.C.S. (Pre) 2016]

(a) 31,000 km
(b) 40,000 km
(c) 50,000 km
(d) 64,000 km

Correct Answer: (b) 40,000 km

Solution:Earth's equatorial perimeter is about 40,090.28 km. This distance is covered by Earth in 24 hours and this indicates that cruising speed of Earth on its axis per hour is 40,090.28 km/ 24 hour = 1670 km/ hour (approx). According to this calculation the cruising speed per minute is = 1670 km/60 min = 27.8 km/ min. Thus, none of the given answers is correct, Note In this question rotating should be on the place of revolving.

36. The Earth's axis of rotation (polar axis) is always inclined at an angle of [U.P.P.C.S. (Pre) 2016]

(a) 23.0° from the elliptic axis
(b) 23.1° from the elliptic axis
(c) 24.5° from the elliptic axis
(d) 23.5° from the elliptic axis

Correct Answer: (d) 23.5° from the elliptic axis

Solution:The Earth rotates about an imaginary line that passes through the North and South poles of the planet. This line is called the axis of rotation. The Earth axis of rotation is always inclined at an angle of 23°30' (23.5°) from the elliptic axis.

37. Consider the following statements: [I.A.S. (Pre) 2005]

1. The axis of the earth's magnetic field is inclined at 23 and a half degrees to the geographic axis of the earth.

2. The earth's magnetic pole in the northern hemisphere is located on a peninsula in northern Canada.

3. Earth's magnetic equator passes through Thumba in South India.

Which of the Statements given above is/are correct?

(a) 1, 2 and 3
(b) 2 and 3
(c) 2 only
(d) 3 only

Correct Answer: (d) 3 only

Solution:The axis of the magnetic field of Earth is different at different ces, not equally inclined at places, 1 23. Thus, statement 1 is 2 wrong. Earlier the magnetic pole of the Earth in Northern hemisphere is situated at Queen Elizabeth Island of Northern Canada not on a peninsula, thus, statement (2) is also incorrect. Thumba is an ideal location for satellite launches because of its proximity to the geomagnetic equator. This is the reason for establishing Thumba Equatorial Rocket Launching Station (TERLS) here as it proves to be a suitable place for satellite launch. Thus statement 3 is true, and option (d) is correct.

38. Consider the following statements and select the correct answer from the codes given below: [U.P.P.C.S. (Pre) 2000]

1. The northern end of the earth's axis is called North Pole.

2. 45° latitude is half of the length of the equator.

3. There is parallelism of the earth's axis.

4. The earth's speed of revolution is faster in aphelion position.

Code:

(a) 1 and 2
(b) 2 and 3
(c) 3 and 4
(d) 1 and 3

Correct Answer: (d) 1 and 3

Solution:The north pole is the northest point of Earth i.e. northern end of the Earth's axis is called North pole. So, statement (1) is true. 45° latitude passes from the middle of the equator and poles. The length of 45° parallel line is 28343.892 km, while the length of the equator is 40090.28 km. and so the 45° parallel is not half of the length of the equator and statement (2) is wrong. Parallelism of the Earth's axis means as Earth revolves around the sun, Earth's axis remain parallel to its previous positions. The situation of Aphelion occurs on 4 July, when the distance between the Sun and Earth is maximum and in the situation of Aphelion the cruising speed of Earth goes slow. Thus, statement (4) is wrong.

39. The causes of Day and Night is- [R.A.S./R.T.S. (Pre) 2000, R.A.S./R.T.S. (Pre) 1999]

(a) Earth-rotation
(b) Rotation of Earth on its axis
(c) Tilt of Earth's axis
(d) Moon's rotation

Correct Answer: (b) Rotation of Earth on its axis

Solution:The Earth experiences day and night as a result of Earth rotation on its axis. Earth takes around approx. 24 hours to complete one rotation. When a place on Earth faces Sun it has Day time when it faces away from Sun it has night.

40. When the length of day and night is equal the Sunrays falls perpendicular at/- [Uttarakhand P.C.S. (Pre) 2002]

(a) North pole
(b) Equator
(c) South pole matra
(d) Tropic of cancer

Correct Answer: (b) Equator

Solution:The sunrays fall perpendicular at the equator twice in a year (on 21 March and on 23 September). On these dates, the duration of day and night becomes an equal i.e. 12-12 hour, in both of the hemispheres.