Scintillation of StarsHardQuestion 20224
Question
Stars twinkle (scintillate) but planets generally do not because:
- AStars are farther away so light is weaker
- BStars are point sources — atmospheric refraction fluctuations significantly affect them; planets subtend a disk that averages out fluctuationsCorrect
- CPlanets emit their own light
- DStars have cooler surfaces
Correct answer
Stars are point sources — atmospheric refraction fluctuations significantly affect them; planets subtend a disk that averages out fluctuations
Explanation
Atmospheric turbulence causes random refraction changes. Stars are point sources so small deflections drastically change apparent brightness. Planets subtend a small (but non-zero) angular disk — the many rays from across the disk average out, reducing scintillation.