The Universe (Part-5)

Total Questions: 52

21. On which date day and night are of equal duration? [M.P.P.C.S. (Pre) 1992]

Correct Answer: (b) 23 September
Solution:Day and Night are of equal duration on the day of Equinox. Equinox literally means "equal day and equal night".

An equinox is an astronomical event in which Sun is vertically overhead of the equator, which occurs twice each year, i.e., 20/21 March and 22/23rd September. Therefore, in the given option 23rd September is the correct answer.

22. Equinox, the two periods in the year when day and night are equal, occurs on: [U.P. Lower Sub. (Spl) (Pre) 2004]

Correct Answer: (a) 21 March and 23 September
Solution:Day and Night are of equal duration on the day of Equinox. Equinox literally means "equal day and equal night".

An equinox is an astronomical event in which Sun is vertically overhead of the equator, which occurs twice each year, i.e., 20/21 March and 22/23rd September. Therefore, in the given option 23rd September is the correct answer.

23. Where are day and night equal throughout the year? [M.P.P.C.S. (Pre) 1995]

Correct Answer: (c) Equator
Solution:Day and night are of equal duration on Equator (12 hours each). Duration of day and night varies in the direction of north or south to the equator. There is no winter season on the equator. It only experiences wet and dry weather.

24. At the time the summer solstice in the northern hemisphere the length of the day will be 12 hours at the: [U.P.P.C.S.(Pre) 1997]

Correct Answer: (d) Equator
Solution:Two types of solstices occur in a year (i) Summer Solstice (ii) Winter Solstice. The sun reaches at Tropic of Cancer in the month of June in Northern hemisphere and the Summer solstice takes place and just opposite to it in Southern hemisphere Winter Solstice takes place.

At the time of summer solstice longest day and shortest night occur in Northern hemisphere, but in the Southern hemisphere shortest day and largest night occur. At the same time, there is no much difference in days and nights at the Equator. Therefore option (d) is the correct answer.

25. In the northern hemisphere, the longest day of the year normally occurs in the: [I.A.S. (Pre) 2022]

Correct Answer: (b) Second half of the month of June
Solution:The longest day of the year in the Northern hemisphere usually occurs in the second fortnight of June. This usually occurs on the date of 20 or 21 June. And in the Southern Hemisphere, the longest day of the year occurs in the second fortnight of the December.

26. The shortest day of the year in Northern hemisphere is on- [47 B.P.S.C. (Pre) 2005 M.P.P.C.S. (Pre) 1990]

Correct Answer: (b) 22 December
Solution:The shortest day of the year in Northern hemisphere occurs during Winter solstice on 21/22 December. Contrary to it on 20/21 June longest day occurs in Northern hemisphere during the Summer solstice. Opposite to it, in Southern hemisphere, the shortest day occurs on 20/21 June and longest day on 21/22 December.

27. Which is the longest day of the year? [M.P.P.C.S. (Pre) 2015]

Correct Answer: (e) None of the above
Solution:The shortest day of the year in Northern hemisphere occurs during Winter solstice on 21/22 December. Contrary to it on 20/21 June longest day occurs in Northern hemisphere during the Summer solstice.

Opposite to it, in Southern hemisphere, the shortest day occurs on 20/21 June and longest day on 21/22 December.

28. Which of the following is the longest day of the year? [U.P.P.C.S. (Pre) 1992]

Correct Answer: (c) 21 June
Solution:The shortest day of the year in Northern hemisphere occurs during Winter solstice on 21/22 December. Contrary to it on 20/21 June longest day occurs in Northern hemisphere during the Summer solstice. Opposite to it, in Southern hemisphere, the shortest day occurs on 20/21 June and longest day on 21/22 December.

29. The Longest day in southern Hemisphere is [48th to 52nd B.P.S.C. (Pre) 2008]

Correct Answer: (b) 22 December
Solution:The shortest day of the year in Northern hemisphere occurs during Winter solstice on 21/22 December. Contrary to it on 20/21 June longest day occurs in Northern hemisphere during the Summer solstice.

Opposite to it, in Southern hemisphere, the shortest day occurs on 20/21 June and longest day on 21/22 December.

30. On which of the following dates your shadow at noon is the smallest ? [U.P.P.C.S. (Pre) 2006]

Correct Answer: (c) June 21
Solution:In the course of a year, the earth's revolution around the Sun with its axis inclined at 66½ to the plane of the ecliptic changes the apparent altitude of the midday Sun.

After the March equinox, the sun appears to move north and is vertically overhead to the tropic of cancer (23) on about 21 June (summer solstice). Since the sun is vertically overhead at noon of 21 June, 0º shadow is formed.