We can see the Sun even when it is a little below the horizon because of atmospheric refraction of light.

Quick Scoop

When the Sun is just below the geometric horizon, its light is still passing through Earth’s atmosphere toward you.

Because air density increases closer to Earth’s surface, the atmosphere acts like a set of layers with different refractive indices that bend (refract) the sunlight downward along a curved path.

So even though the Sun is physically below the horizon line, the bent rays reach your eyes as if they came in a straight line from a point above the horizon, making the Sun appear slightly higher than it really is.

Key points

  • The correct fill‑in is: “because of atmospheric refraction (refraction of light).”
  • Layers of air with different densities bend light towards the denser regions, curving the path of sunlight near sunrise and sunset.
  • This effect lets us see the Sun for a few minutes before it has actually risen and after it has actually set.

One-line exam-style answer

We can see the Sun even when it is a little below the horizon because of atmospheric refraction of light in the Earth’s atmosphere.

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Learn why we can see the sun even when it is little below the horizon because of atmospheric refraction, with a simple explanation and exam-ready answer.