A Retreating Thunderstorm at Sunset

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.

Explanation: What type of cloud is that? This retreating cumulonimbus cloud, more commonly called a thundercloud, is somewhat unusual as it contains the unusual bumpiness of a mammatus cloud on the near end, while simultaneously producing falling rain on the far end.

Taken in mid-2013 in southern Alberta, Canada, the cloud is moving to the east, into the distance, as the sun sets in the west, behind the camera.

In the featured image, graphic sunset colors cross the sky to give the already photogenic cloud striking orange and pink hues.

Further in the distance, a rising, waxing, gibbous moon is visible on the far right.