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Câu hỏi: Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer for each of the questions from 35 to 42.
Many parameters are used to describe a star. One of them is its temperature, which can be determined by simple observation; the color of a star and its temperature are related. Once the color of a star is identified, its temperature can be calculated through the use of scientific principles such as Wien's Law.
There are different types of stars in the universe. For our purposes, we can classify them into categories: variable and binary. Variable stars are those which show some degree of variability in their luminosity and magnitude. Luminosity refers to the amount of energy radiated by a star, while magnitude refers to its brightness. At times the degree of variability may be high, requiring a telescope with an equally high light-gathering power. This can be achieved by using a lens of large diameter, such as that of a reflecting telescope. Binary stars are those found in pairs that revolve around a common center. The closest star to the sun, Proxima Centauri, is a binary star. To observe a binary star, the resolving power of a telescope - its ability to distinguish between two close objects having a small angular separation " must be very high.
Stellar astronomy is possible for everyone, well beyond mere looking at the sky with the naked eye in order to identify constellations. With two basic types of telescopes and rudimentary knowledge, much exploration can be achieved.
Why does the author writethat "stellar astronomy is possible for everyone"?
A. To emphasize that it is easy to become an astronomer
B. To encourage people to try observing stars
C. To show that most people know a lot about stars
D. To explain why astronomy is popular
Many parameters are used to describe a star. One of them is its temperature, which can be determined by simple observation; the color of a star and its temperature are related. Once the color of a star is identified, its temperature can be calculated through the use of scientific principles such as Wien's Law.
There are different types of stars in the universe. For our purposes, we can classify them into categories: variable and binary. Variable stars are those which show some degree of variability in their luminosity and magnitude. Luminosity refers to the amount of energy radiated by a star, while magnitude refers to its brightness. At times the degree of variability may be high, requiring a telescope with an equally high light-gathering power. This can be achieved by using a lens of large diameter, such as that of a reflecting telescope. Binary stars are those found in pairs that revolve around a common center. The closest star to the sun, Proxima Centauri, is a binary star. To observe a binary star, the resolving power of a telescope - its ability to distinguish between two close objects having a small angular separation " must be very high.
Stellar astronomy is possible for everyone, well beyond mere looking at the sky with the naked eye in order to identify constellations. With two basic types of telescopes and rudimentary knowledge, much exploration can be achieved.
Why does the author writethat "stellar astronomy is possible for everyone"?
A. To emphasize that it is easy to become an astronomer
B. To encourage people to try observing stars
C. To show that most people know a lot about stars
D. To explain why astronomy is popular
Câu trả lời này dựa vào thông tin "well beyond mere looking at the sky with the naked eye in order to identify constellations."
Đáp án B.