Question

The length of its day and the tilt of its axis are almost identical to those of the earth. ‘This is true of _____________.
A) Uranus
B) Neptune
C) Saturn
D) Mars

Answer 1

Hint: The Earth revolves around its axis once every 24 hours and orbits the sun once every 365 days. The Earth's rotation on its axis, not its orbit around the sun, causes day and night. The word 'one day' refers to the time it takes the Earth to rotate once on its axis, which includes both day and night.

Complete answer:
Length of day on Earth – When you think of a day, you usually take the shape of one cycle of day to night. This is referred to as a solar day. A solar day lasts around 24 hours on Earth. The Earth's orbit, on the other hand, is elliptical, which means it isn't a complete circle. This means that some solar days on Earth are a few minutes longer and some are a few minutes shorter than 24 hours.

Another way to count a day is to count how long it takes a planet to rotate entirely around and complete one full rotation. This is referred to as a sidereal day. A sidereal day lasts roughly exactly 23 hours and 56 minutes on Earth.

A day is a time it takes the Earth to complete one rotation around its axis, which takes approximately 24 hours. A solar day is a period of time between two consecutive periods when the Sun reaches its greatest point in the sky.

Let us analyze the given options:
Option A) Uranus: The duration of a planet's day is determined by its orbital velocity and mass. Because all planets have various masses and are at different distances from the sun (Star), their planet days will be different. So, Uranus' day is 17 hours long which is not identical to earth. Hence, this option is incorrect.

Option B) Neptune: Each planet experiences fluctuations in day and night length. The axis of each planet is slanted at a distinct angle. So, Neptune's day is 16 hours long which is not similar to the earth’s day. Hence, this option is incorrect.

Option C) Saturn: Because they, too, are inclined on their axes, other planets undergo fluctuations in day and night length. The axis of each planet is tilted at a different angle. So, Saturn's day is 10 hours long which is not similar to the length of the day on earth. Hence, this option is incorrect.

Option D) Mars: Mars has a daily cycle that is quite similar to Earth's. Its solar day is 24 hours, 39 minutes, and 35 seconds long, and the sidereal day is 24 hours, 37 minutes, and 22 seconds long. As a result, a Martian day (referred to as "sol") is roughly 40 minutes longer than an Earth day. Hence, this option is correct.

Therefore, Option ‘D’ i.e, Mars is the correct answer because it is true that the length of the day on Mars and the tilt of its axis are nearly identical to those on Earth.

Note: On Mars, time is readily split into days and years depending on its rotation rate and orbit. Sols, or Martian solar days, are 39 minutes and 35 seconds longer than Earth days, and a Martian year consists of 668 sols (687 Earth days).