Measuring astronomical distances Quiz
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5 questions, one answer each
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1. A star has a parallax angle of 0.25 arcsecond. What is its distance?
- A. 0.25 pc
- B. 2.5 pc
- C. 4.0 pc
- D. 40 pc
2. Why can parallax not be used to find the distance to a distant galaxy?
- A. The galaxy is too bright
- B. The parallax angle is too small to measure
- C. The Earth does not move enough
- D. Galaxies do not emit light
3. A star has intensity I at Earth. A second identical star is three times as far away. What is its intensity?
- A. I/3
- B. I/6
- C. I/9
- D. 3I
4. What must be known for an object to be used as a standard candle?
- A. Its distance
- B. Its luminosity
- C. Its surface temperature
- D. Its mass
5. A student finds the distance to a galaxy with a standard candle but ignores dust between the galaxy and Earth. How does this affect the result?
- A. The distance is overestimated, because the intensity measured is too low
- B. The distance is underestimated, because the intensity measured is too low
- C. The distance is unaffected
- D. The distance is overestimated, because the luminosity is too high