Question
Which of the following rocks is not expected to occur on the moon?
The correct answer is
Sandstone
Moon Rock Composition
The Moon's surface geology is primarily composed of igneous rocks formed from volcanic activity and impacts. Understanding the conditions required for different rock types helps determine their presence.
Analysis of Lunar Rocks
- Anorthosite: Found in the lunar highlands, these are light-colored, feldspar-rich rocks. They are a major component of the Moon's crust.
- Norite: This is a mafic intrusive igneous rock, similar to gabbro. Samples containing norite have been found, indicating its presence, likely within the deeper crust or ejecta from impacts.
- Basalt: Dark-colored, fine-grained extrusive igneous rocks, basalts are abundant in the lunar maria (seas). They formed from ancient volcanic eruptions.
- Sandstone: This is a sedimentary rock. Sedimentary rocks on Earth form through processes like erosion, deposition, and cementation, typically requiring liquid water and a substantial atmosphere.
Why Sandstone is Unexpected on the Moon
The Moon lacks the necessary conditions for sandstone formation:
- No liquid water: Essential for transporting and cementing sediment grains.
- Thin or no atmosphere: Prevents weathering and erosion processes that create sand, and lacks pressure needed for some sedimentary formations.
- Limited geological activity: The Moon's surface is dominated by impact events and ancient volcanism, not the widespread erosion and deposition seen on Earth.
Conclusion on Moon Rocks
Based on the Moon's geological environment, sandstone is the rock type least expected to be found there compared to the igneous rocks like anorthosite, norite, and basalt.
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Important Questions from Planetary Bodies
- The correct sequence of planets in order of increasing surface temperature is:
- Atmosphere of planet Mars is almost entirely made up of $\text{CO}_2$. But the surface temperature of Mars is less than that of the Earth because:
- Consider two planets A and B with radii $2r$ and $r$, respectively. Let their distances from the Sun be $d$ and $2d$, respectively. The solar constants for A ($F_{\text{SA}}$) and B ($F_{\text{SB}}$) are related by
- Consider two planets 'A' and 'B' with the following characteristics. The relationship between $T_1$ and $T_2$ is
Distance from the Sun Radius of the planet Incident Solar flux density Equivalent temperature Planet A $d_1$ $r_1$ $F_1$ $T_1$ Planet B $d_2 = 4d_1$ $r_2 = 2r_1$ $F_2$ $T_2$ - Venus is closer to the Sun than Earth, and therefore solar energy incident on Venus is higher than that on Earth. However, the effective radiating temperature of Venus is lower than that of the Earth, because
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