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From Aquila, look a little to the northeast of Altair, past the small arrow-shape of Sagitta, for a tight kite of four stars with a short tail: that's Delphinus. It doesn't have a Vega or a Deneb to anchor it, so it helps to have Aquila found first. For the Summer Triangle that dominates this whole part of the sky, see Cygnus. Delphinus sits at a declination of roughly +11° to +16°, similar to Aquila — up for something close to half of each 24-hour period from Ohio's latitude, not circumpolar, best viewed full dark in August and September once your eyes have had a few minutes to adjust.

Star	RA (h)	Dec (°)	Mag	Distance	Name
Sualocin (Alpha Del)	20.660	+15.91	3.77	not verified — omitted	Reversed spelling of "Nicolaus" — see below
Rotanev (Beta Del)	20.627	+14.60	3.63	not verified — omitted	Reversed spelling of "Venator" — see below
Dhanishta (Gamma-1 Del)	20.778	+16.12	3.87 (combined double)	not verified — omitted	IAU name for the brighter half of a fine double star
Delta Del	20.725	+15.07	4.43	~223 ly	No proper name
Aldulfin (Epsilon Del)	20.553	+11.30	4.03	not verified — omitted	Arabic ðanab ad-dulfīn via Latin cauda delphini, "the dolphin's tail"; named by the IAU in 2017

Delphinus doesn't reward you with a lot of verified nearby astrophysics — it rewards you with a shape and a story.

Delphinus's two brightest stars carry the best inside joke in the night sky. Alpha and Beta Delphini are named Sualocin and Rotanev — odd, meaningless-looking names that first appeared in print in the Palermo Catalogue of 1814, compiled by the Italian astronomer Giuseppe Piazzi (who, a decade earlier, had discovered Ceres, the first asteroid found). Read backward, letter by letter, Sualocin spells Nicolaus and Rotanev spells Venator — together, Nicolaus Venator, the Latinized form of Niccolò Cacciatore, Piazzi's assistant and eventual successor as director of Palermo Observatory. The Latinization is a direct translation, not just a sound-alike: cacciatore is Italian for "hunter," and venator is Latin for the same thing.

It's usually told as Cacciatore quietly naming a pair of stars after himself and getting away with it — which would make him the only person in the history of astronomy to pull that off. Ian Ridpath, whose research into the origins of star names is the standard reference on this kind of question, notes a second possibility that's just as plausible: Piazzi himself may have applied the names, as a tribute to his protégé and heir apparent — the French word dauphin, meaning both "dolphin" and "heir to the throne," may be doing quiet double duty. Either way, the joke wasn't solved publicly until the English astronomer Thomas Webb worked out the reversal. What started as a private joke or a private tribute has since become official: Sualocin and Rotanev are now the internationally recognized formal names of Alpha and Beta Delphini.

Delphinus is one of Ptolemy's 48 constellations in the Almagest. Dolphins were a familiar, friendly sight to Greek sailors, and two separate stories put one in the sky. In the version given by Eratosthenes, the dolphin is Poseidon's messenger: when the sea god fell for the Nereid Amphitrite and she fled his advances, Poseidon sent a dolphin after her, and it coaxed her back with gentle persuasion. Grateful, Poseidon set its image among the stars.

The second version, from Hyginus and Ovid, is more dramatic: this is the dolphin that saved Arion, a real poet and lyre player of the 7th century BCE. Returning from a concert tour by ship, Arion learned the crew meant to rob and kill him; he asked to sing one final song before he died, and his music drew a school of dolphins alongside the ship. Arion leapt overboard, and one of the dolphins carried him safely to shore, where he lived to see his attackers brought to justice. In this telling, Apollo placed both the dolphin and Arion's own lyre among the stars — which is why the neighbouring constellation is Lyra.

The constellation's popular nickname, Job's Coffin, is old enough that no one now knows who coined it or why — an honest gap, not a settled fact dressed up as one. In China, the four stars of Job's Coffin plus one more formed Hugua, and five more nearby stars formed Baigua: a matched pair of gourds, one dried and useful, one gone soft and rotten.

• NGC 6934, a globular cluster roughly 52,000 light years away, magnitude 8.8, discovered by William Herschel in September 1785.
• NGC 6905 ("Blue Flash Nebula"), a planetary nebula estimated at roughly 5,500–8,500 light years away (distance estimates for small planetary nebulae like this one are often this uncertain), magnitude 10.9, discovered by Herschel in 1784.

Date	Event
c. 150 CE	Ptolemy catalogues Delphinus in the Almagest.
1784	William Herschel discovers the planetary nebula later catalogued as NGC 6905.
September 1785	William Herschel discovers the globular cluster NGC 6934.
1814	Giuseppe Piazzi's Palermo Catalogue publishes the names Sualocin and Rotanev.
1930	The IAU adopts Eugène Delporte's precise boundaries for the 88 constellations, fixing Delphinus's borders on the sky.
1992	Rho Aquilae's own proper motion carries it across the border from Aquila into Delphinus.
2017	The IAU formally names Epsilon Delphini "Aldulfin."

• Aquila — the nearest bright neighbour, and the source of the star (Rho Aquilae) drifting into Delphinus.
• Lyra — Arion's own lyre, placed in the sky beside this dolphin in the same myth.
• Cygnus — the Summer Triangle that anchors this whole part of the sky.