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The Cat’s Eyes

Right Ascension17h31 to 17h34
Declination-37° 6' to -37° 18'
Separation0° 35' 53"
Brightest StarShaula
Optimum VisibilityJune / July

A name sometimes given to a pair of blue-white stars of similar brightness that lie close together at the tip of Scorpius' tail. These two stars, Shaula and Lesath, are typically seen as the stinger of the Scorpion, or sometimes as the barb at the end of the Fishhook, but together they also form a small asterism in their own right.

This image shows the Cat's Eyes shining against the backdrop of the Milky Way. The brighter star to the east (left) is Shaula or Lambda Scorpii, while the fainter of the two 'eyes' to the west (right) is Lesath or Upsilon Scorpii. Imagery provided by Aladin sky atlas

The brighter of the Cat's Eyes is Shaula or Lambda Scorpii, with a visual magnitude of +1.6 (placing it among the thirty brightest stars in the sky). The other Eye star is Lesath or Upsilon Scorpii, with a visual magnitude of +2.7 (formally less than half as bright as Shaula, though still clearly visible to the naked eye). The two stars lie less than a degree apart in the sky, closer together than the diameter of the Moon's disc.

The stars of the Cat's Eyes are not physically connected, but they do lie relatively close to one another in space. Shaula is marginally the closer of the two, at a distance of about 570 light years from the Sun, but Lesath lies just ten light years further away. Both stars share a similar physical structure, each being a B-type subgiant more than ten times the Sun's diameter, and thousands of times more luminous. Shaula is a short-period pulsating variable of the Beta Cephei type, within a system with at least two faint companion stars. Lesath is a rather less complex star, with no variability or stellar companions recorded.


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