Which of the following statements is / are correct about planets ?
(A) They are lit by the light of the stars.
(B) They are made up of only rocks.
(C) All planets have their moons.
Options:
- AOption (a)
Only (A)
- BOption (b)
Only (A) and (B)
- COption (c)
Only (B) and (C)
- DOption (d)
All (A), (B) and (C)
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Correct answer
Only (A)
Why this answer is correct
The Correct answer is: Only (A)
Key Points
- They are lit by the light of the stars:
- This statement is correct.
- Planets do not produce their own light but reflect the light of stars, primarily their host star, which in our Solar System is the Sun.
- When we see planets in the night sky, we are seeing the sunlight reflected off their surfaces or atmospheres.
- They are made up of only rocks:
- This statement is incorrect.
- Planets can be made of various materials, not just rocks. In our Solar System, for example, we have rocky planets (terrestrial planets) like Earth and Mars, and gas giants like Jupiter and Saturn that are primarily composed of hydrogen and helium.
- There are also ice giants like Uranus and Neptune, which contain a mixture of water, ammonia, and methane ices.
- All planets have their moons:
- This statement is incorrect.
- Not all planets have moons. For example, in our Solar System, Mercury and Venus do not have any moons.
- Moons are natural satellites that orbit planets, and their presence depends on various factors including the planet's mass and gravitational influence.
Additional Information
- Planet Classification:
- Planets are classified into different types based on their composition and location in the solar system.
- Terrestrial planets (like Earth and Mars) are rocky and have solid surfaces.
- Gas giants (like Jupiter and Saturn) are composed mainly of hydrogen and helium and do not have a well-defined solid surface.
- Ice giants (like Uranus and Neptune) contain more ices in their composition.
- Exoplanets:
- Planets that orbit stars outside our Solar System are called exoplanets.
- Thousands of exoplanets have been discovered, exhibiting a wide variety of sizes, compositions, and orbital characteristics.
- Moons and Natural Satellites:
- Moons are natural satellites that orbit planets. They can vary greatly in size and composition, ranging from small asteroid-like bodies to large objects with their own atmospheres and geological activity.
- Some moons, like Earth's Moon, are thought to have formed from debris resulting from collisions, while others may have been captured by the planet's gravity.