The apparent position of a star keeps changing slightly due to the continuously varying physical conditions of the Earth’s atmosphere. This fluctuation in the apparent position, coupled with the fact that stars are distant and approximate point-sized sources of light, ...

The atmosphere bends starlight towards the normal during atmospheric refraction. As a result, when a star is viewed near the horizon, its apparent position appears slightly higher (above) than its actual position.

The twinkling of stars is caused by atmospheric refraction of starlight. When starlight enters the Earth’s atmosphere, it undergoes continuous refraction due to the gradually changing refractive index of the atmospheric medium.

The twinkling of stars is a similar phenomenon to the wavering in hot air, but on a much larger scale. Atmospheric refraction in the Earth’s atmosphere causes variations in the refractive index of air at different altitudes, leading to the ...

The air above a heat source becomes hotter and less dense than the cooler air above it. This temperature difference causes variations in the refractive index of the air. As a result, the apparent position of objects seen through this ...