Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2023 June 26
An orange sky hovers above snow-covered mountains. A blurry line
divides the orange sky from a darker sky. In the foreground are hills
and a house.
Please see the explanation for more detailed information.

The Belt of Venus over Mount Everest
Image Credit & Copyright: Soumyadeep Mukherjee

Explanation: You've surely seen it, but you might not have noticed it. During a cloudless twilight, just before sunrise or after sunset, part of the atmosphere above the horizon appears slightly dark and off-colour. Called the Belt of Venus, this transitional band between the dark eclipsed sky and the bright day sky can be seen most prominently in the direction opposite the Sun. Straight above, blue sky is normal sunlight reflecting off the atmosphere, while near the horizon the clear sky can appear more orange or red. In the Belt of Venus, the atmosphere reflects more light from the setting (or rising) Sun and so appears more red. Featured here, the Belt of Venus was photographed over several Himalayan mountains including, second from the right, Mount Everest, the tallest mountain on Earth. Although usually not mentioned, the belt is frequently caught by accident in other photographs.

Tomorrow's picture: ultraviolet red planet


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