🔍 Key Concepts

• Astronomical refraction is the bending of light from a celestial body as it passes through Earth’s atmosphere • Refraction makes objects appear shifted from their true (geometric) position in the sky • The effect depends mainly on the body’s altitude above the horizon, not on hemisphere or left/right position

💭 Think About

• Think about how light bends when it passes from thinner air (higher altitude) into denser air (near the surface). In which direction does the apparent position shift? • Is refraction primarily a vertical effect (up/down) or a sideways effect (left/right) when observing stars and planets? • When a star is very close to the horizon, navigators can still see it even though geometrically it might already be below the horizon. What does that suggest about how its apparent altitude is changed?

✅ Before You Answer

• Confirm whether refraction changes the apparent altitude (height above horizon) or the sideways bearing of the body • Check if hemisphere (Northern vs Southern) actually affects the direction of astronomical refraction • Remember that refraction is strongest near the horizon and consider whether that would make bodies seem higher or lower than their true positions