Here's why stars appear higher:
1. Density Gradient: The Earth's atmosphere is not uniform in density. It is denser near the ground and becomes less dense as you move higher up. This difference in density creates a gradient.
2. Bending of Light: When light from stars enters the Earth's atmosphere, it encounters this density gradient. As light passes from a less dense region (outer space) to a denser region (atmosphere), it bends (refracts) toward the normal (perpendicular) to the boundary between the two media. This phenomenon is known as refraction.
3. Apparent Position: Due to refraction, the path of light from stars is slightly bent as it enters the Earth's atmosphere. This bending causes stars to appear slightly displaced from their actual positions. They appear higher in the sky than they would if there were no atmosphere.
4. Effect of Distance: The amount of refraction depends on the angle at which the light strikes the atmosphere and the density gradient. Stars near the horizon experience more refraction compared to those at higher altitudes. Therefore, stars close to the horizon appear more elevated than those higher in the sky.
5. Twinkling: The uneven distribution of density within the atmosphere can cause slight variations in the amount of refraction, leading to a shimmering or twinkling effect in stars.
Astronomical refraction is important in astronomical observations and calculations, as it affects the apparent position and brightness of celestial objects. It also contributes to the beautiful twinkling of stars that we see at night.
