The “Mad Bull” of the August Sky

Even a casual look at the night sky south of Hercules reveals a small group of stars that looks like a mad little bull charging east towards the Milky Way.  This horned beast is a striking sight, and, frankly, a little unsettling.  But it points the way to some lovely star fields that make a lovely sight in binoculars or a small scope.

This little star pattern (or asterism) is called Taurus Poniatowski, or Poniatowski’s Bull.  It was named in 1777 by Abbe Poszobut after King Stanislaus Poniatowsk of Poland.  For a time, this little group was considered a constellation,  as in the old star map above, though it’s now part of the large constellation Ophiuchus.  While “Taurus P” didn’t make the cut as a modern constellation, the name of this star group remains.

And it’s a pretty little group.  In binoculars, the background is flecked with fainter 9-th and 10th- magnitude stars that straggle off the western edge of the Milky Way.  The V-shaped head of the bull consists of three stars: 67, 68, and 70 Ophiuchi.  The two stars at the back end of this little beast are gamma and beta Ophiuchi (Cebalrai).  Long-time readers will remember meeting 70 Oph a couple of years ago… it’s a fine yellow-orange double star and one of the few you can see revolve during a human lifetime.  In binoculars, it makes a nice contrast with the blue-white 67 Oph.

Map of Taurus Poniatowski in the constellation Ophiuchus (click to enlarge)

This asterism can be seen in both hemispheres, though it will appear upside down in the southern hemisphere.

While it’s off the Milky Way, Taurus Poniatowski holds a few sparse open star clusters and one dazzler, IC4665, just one degree northeast of beta Ophiuchi.  We’ll meet this star cluster and a few others next week.  But for now, that’s it!