One way to distinguish stars from planets,particularly when they appear near the horizon,is that stars appear to twinkle and planets shine steadily.Which of the following statements is a reasonable explanation for this phenomenon?
A) Stars actually do twinkle-shine with a light that flickers bright and dim-whereas planets shine with a steady, unwavering light.
B) The light from planets is so much brighter than the light from stars (when they are observed from Earth) that it is unaffected by air movement in Earth's atmosphere.
C) The disk of a planet, as observed from Earth, appears larger than the disk of a star. Thus, if refraction through moving air in Earth's atmosphere makes the planet's disk appear to move about slightly, there will normally be a central part of the disk that shines steadily and does not appear to twinkle.
D) Because light from planets is reflected, it is unaffected by the refraction in Earth's atmosphere.

Question

Quizplus · Accepted Answer

The disk of a planet appears larger than the disk of a star when observed from Earth, allowing for a central part of the planet's disk to shine steadily and not appear to twinkle. Stars are point sources of light and any refraction through moving air in Earth's atmosphere causes their light to appear to flicker bright and dim. The brightness of the light from planets compared to stars has no impact on this phenomenon. Planets reflecting light, rather than emitting it, also has no impact on the refraction and the twinkling of stars.

One Way to Distinguish Stars from Planets,particularly When They Appear