Delphinus
Delphinus, the little dolphin leaping beside the Milky Way. With its dainty rhombus shape, it carries the tale of the dolphin that saved a musician.
Quick Facts
At a glance- Brightest star
- Rotanev · m3.63
- Latin name
- Delphinus
- Latin genitive
- Delphini
- Main stars
- 5
Science
The scienceDelphinus is small and faint, yet its stars huddle close to form a distinct dainty rhombus (the dolphin's body) with a short tail, making it surprisingly easy to find at the edge of the Milky Way. The names of its chief and second stars, "Sualocin" and "Rotanev," hold an amusing secret: Niccolò Cacciatore, an assistant at the Palermo Observatory in the 19th century, slyly gave them by reversing his own Latinized name, Nicolaus Venator.
Mythology
How it became a constellationWhen the nymph Amphitrite, whom the sea god Poseidon wished to marry, fled and hid herself, Poseidon sent a dolphin to find her and win her over. When the dolphin carried out its task splendidly, Poseidon honored the deed by setting it among the stars as a constellation. In another tale, the musician Arion, seized by sailors and thrown into the sea, was carried safely to shore on the back of a dolphin enchanted by his beautiful song.
Observing Guide
how to observe🔭 How to find it
Inside the Summer Triangle (Vega, Altair, and Deneb), move a little northeast from Altair (in Aquila) and you'll see a dainty diamond of small stars clustered close together — this is Delphinus. Its clear shape — a diamond (the dolphin's body) with a short tail attached — means that despite its small size, it's surprisingly easy to spot at the edge of the Milky Way. It's also nicknamed "Job's Coffin."
✨ What to look for
For such a small constellation, Delphinus holds two globular clusters: NGC 6934, and the more distant and fainter NGC 7006 — both requiring a medium or larger telescope. There's also a planetary nebula, NGC 6905, known as the "Blue Flash Nebula." On the whole, though, bright targets are few, so it's more rewarding simply to enjoy the constellation's charming little shape.
📍 Where to see it (US · Canada · UK · Australia)
At +11° to +16° declination, Delphinus is well placed for northern observers, riding high in the south on summer-to-early-autumn nights (July–October) from the US, Canada, and the UK; because its stars are faint, the little diamond stands out best under a dark sky. From Australia the dolphin appears in the northern sky during the southern winter and spring — lower down, but still easy to pick out.
Stars
Main stars (J2000.0 equatorial)FAQ
Frequently askedWhat is the brightest star in Delphinus?
The brightest star in Delphinus is Rotanev, shining at apparent magnitude 3.63.
When and where can you see Delphinus?
At +11° to +16° declination, Delphinus is well placed for northern observers, riding high in the south on summer-to-early-autumn nights (July–October) from the US, Canada, and the UK; because its stars are faint, the little diamond stands out best under a dark sky. From Australia the dolphin appears in the northern sky during the southern winter and spring — lower down, but still easy to pick out.
What is Delphinus and what does it represent?
Delphinus, the little dolphin leaping beside the Milky Way. With its dainty rhombus shape, it carries the tale of the dolphin that saved a musician.