Thursday, January 19, 2023

A CASCADE OF STARS IN THE GIRAFFE

One of the most beautiful asterisms to admire in the sky is Kemble’s Cascade, a series of 20 stars aligned to form an almost perfect straight line. The line has a length of nearly three degrees or, to say it more familiarly, the diameter of five full moons.

Kemble’s Cascade, as mentioned, is not a constellation, but an asterism. Asterism is any group of stars that is recognizable from the rest by its particular geometric configuration. As for the constellations, the stars of the asterisms are not physically bound and appear close together only for a pure perspective effect.

This trail of stars seems to lead to a tiny open cluster known as Jolly Roger, located 3500 light years from Earth and composed of just 60 components. In this image the Jolly Roger is that small grouping of white stars at the top of the image.

The stars that make up Kemble’s Cascade have an apparent magnitude between the fifth and the tenth, while the Jolly Roger appears of sixth magnitude. The brightest stars and the same open cluster are therefore at the limit of visibility to the naked eye and can be observed only under skies in perfect conditions and without light pollution. To be better observed asterism therefore requires at least the use of binoculars, even better if a telescope.

Credit: Tommy Lease.

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