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July 12, 2015

Three tiny constellations stairstep up the eastern sky as it gets good and dark right now. From bottom to top, they’re Equuleus, the little horse; Delphinus, the dolphin; and Sagitta, the arrow. Despite their diminutive sizes, under dark skies two of them are fairly easy to pick out.

The “bottom” step is Equuleus. It’s quite low in the sky as darkness falls, but climbs into better view later on. Even then, though, it’s not much to look at. It’s the second-smallest of the 88 constellations, and you need especially dark skies to see even its brightest stars.

Delphinus stands directly above the little horse, and it’s easier to pick out. Its individual stars are all pretty faint, but together, they form a tight pattern that really does look like a tiny dolphin.

Two of those stars form an astronomical inside joke. They’re named Sualocin and Rotanev — names that first appeared in a star catalog in 1814. The names turned out to be backward spellings of Nicolaus Venator, the assistant director of the observatory that compiled the catalog. He added his name to give himself a bit of cosmic immortality. Other astronomers went along with the gag, and the names are still in use today.

Sagitta forms the top step. It’s the third-smallest constellation. But like Delphinus, its brightest stars form a pattern that’s fairly easy to see under dark skies. The arrow aims toward the lower left — ready to streak across the evening skies of summer.

Script by Damond Benningfield, Copyright 2015

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