The open star cluster in Cygnus known as M29 is also now nicknamed “the Cooling Tower” due to its oddly symmetrical shape, evoking the hyperboloid shape of the chimneys of a nuclear power plant. The principal stars form a box with an open top, sort of.
It’s considered the least-interesting entry in the Messier catalog. I thought it was kind of neat!
Either the last bit of twilight or the limitations of my telescope kept me from seeing the full cluster or its promised backdrop of the Milky Way. I saw a dark patch of sky with six tiny stars in a near-perfect geometrical configuration. They are magnitude 9.5, give or take–tiny but very clear in my telescope.
Cygnus is a great place to go to find nebulae and clusters, not to mention the grand sweep of the Milky Way. Its long axis from south to north parallels the flow of the Milky Way. It’s fun just to put in a wide-angle lens, or one of low-to-moderate magnification, and just go swimming.