Which heavenly body in our Solar System takes nearly the same time to complete one rotation on its axis as it does to complete one revolution around its planet, always keeping the same face turned toward that planet?

Introduction / Context:
Many students notice that the same side of the Moon always faces the Earth. This interesting fact is a result of the Moon taking almost exactly the same time to rotate on its own axis as it takes to revolve once around the Earth. This condition is called synchronous rotation or tidal locking. The question checks whether you can identify which heavenly body has this property from among common options like asteroid, comet, Moon, and Mars.

Given Data / Assumptions:

• We are dealing with one rotation of a body on its axis and one revolution in its orbit.
• The body of interest keeps the same face towards the planet it orbits.
• Options include an asteroid, a comet, the Moon, and the planet Mars.
• We assume standard known facts about the Earth Moon system.

Concept / Approach:
In celestial mechanics, when a body is tidally locked to another, its rotational period and orbital period are equal or nearly equal. This is true for the Earth's Moon, which takes about 27.3 days to both rotate once on its axis and revolve once around the Earth. As a result, we always see essentially the same hemisphere of the Moon from Earth. Asteroids and comets have more irregular rotations and orbits and are not tidally locked in this way to Earth. Mars is a planet with its own rotation and revolution around the Sun, not around Earth, and so it does not satisfy the condition described in the question.

Step-by-Step Solution:
Step 1: Note the key phrase that the body takes nearly the same time for rotation and revolution. Step 2: Recall that the Moon always shows the same face to the Earth, which is a hallmark of tidal locking. Step 3: Tidal locking occurs because the rotational period matches the orbital period. Step 4: Compare this with asteroids and comets, which rotate and revolve irregularly and are not locked to Earth in this manner. Step 5: Therefore, the body described is the Moon, making option C correct.

Verification / Alternative check:
You can verify this fact by observing the Moon over many nights. The pattern of maria and craters visible from Earth remains essentially fixed, proving that we see the same lunar hemisphere. Space missions have photographed the far side of the Moon, which we never see directly from Earth. Astronomical references clearly state that the Moon is tidally locked to the Earth and that its rotation period equals its revolution period relative to Earth.

Why Other Options Are Wrong:
Asteroids are small rocky bodies that generally orbit the Sun and are not tidally locked to Earth, so option A is incorrect. Comets follow elongated orbits around the Sun and are not synchronised in rotation and revolution with Earth, so option B is wrong. Mars is a separate planet orbiting the Sun, not the Earth, and its rotation period is about one Mars day, while its revolution period is about 687 Earth days, so option D does not match the described condition. Only the Moon fits the description of having nearly the same rotation and revolution period with respect to the Earth.

Common Pitfalls:
Some learners mistakenly think that the Moon does not rotate at all because they always see the same side. In reality, it does rotate, but its rotation and revolution periods are equal. Another confusion is to mix up the orbital motion of Mars around the Sun with an orbit around Earth. To avoid such mistakes, always remember that the Earth Moon system is a clear example of tidal locking, where the Moon shows the same face due to matching rotation and revolution times.

Final Answer:
The heavenly body that takes almost the same time to rotate on its axis and to revolve around its planet is the Moon.