Being an astronomer is a fascinating experience. Whether it’s during the day or at night, the sky never fails to offer its wonders. One of the most captivating phenomena to watch out for during the in-between times is crepuscular rays, also known as twilight rays.
Crepuscular rays are essentially sunbeams that appear when the sun is low or has just set, casting a line of light across the sky. These rays may seem familiar, as we often see beams of light radiating from the sun when it’s behind a cloud. However, crepuscular rays are more complex than they appear.
The air is transparent, so we can’t see light passing through it. But when there are particles like dust or haze suspended in the air, the sun’s light illuminates them, causing them to reflect light brightly. If an object such as a cloud or a mountain blocks the sun, particles in that line are in shadow, creating a contrast of light and dark beams that seem to radiate from the sun.
Crepuscular rays are more prominent at sunset due to the accumulation of haze particles in the air during the day. As twilight sets in, the contrast between light and shadow becomes more visible, enhancing the beauty of these rays.
When observing crepuscular rays, it may appear as though they are diverging away from the sun. However, they are actually almost parallel to each other. This optical illusion is a result of perspective, similar to how railroad tracks seem to converge in the distance. In reality, crepuscular rays are parallel, but they appear to converge or diverge based on their position in the sky.
For those interested in space, photographs taken from the International Space Station clearly show that crepuscular rays are parallel, offering a unique perspective on this phenomenon. Additionally, if you look east at sunset, you may notice the Belt of Venus, a pinkish or reddish band on the horizon that is actually Earth’s shadow on its atmosphere.
The Belt of Venus is a stunning sight that occurs as the sun sets and the shadow of Earth is cast on the atmosphere, creating a dark band on the eastern horizon. The reddish colors above the band result from the scattering of light, adding to the beauty of this atmospheric phenomenon.
As an astronomer, paying attention to the sky can unveil countless wonders like crepuscular rays and the Belt of Venus, each offering a deeper appreciation when understood. So, next time you find yourself under the twilight sky, remember to look out for these spectacular natural light shows and marvel at the beauty of our universe.
