Delphinus
What is Delphinus?
Constellations· Summer–autumn evenings (N) · tiny diamond. A tiny diamond of four stars just east of Altair, beside the summer Milky Way — sometimes called "Job's Coffin". Small but crisp, it is easy to find again once learned. Zoom in near Altair in the Sky view.
📍 Visible from where you are right now — computed in your browser
bearing · altitude · rise time · best time tonight
Where Delphinus is in your sky right now: https://nowsky.org/solar/sky?sel=con:Delphinus — location and time set automatically, no login.
Stars of the figure
| Star | Magnitude |
|---|---|
| Rotanev | 3.6 |
| Sualocin | 3.8 |
| Aldulfin | 4.0 |
| Gamma Delphini | 4.3 |
The 4 brightest of the 5 stars used in the figure (5 lines). Lower magnitude means brighter.
Constellation basics
| Season | summer–autumn evenings (N) |
|---|---|
| Brightest star | Rotanev (β, 3.6) |
| How to find | small diamond east of Altair |
| Area rank | 88 |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Frequently asked
- When can I see Delphinus?
- summer–autumn evenings (N).
- How do I find Delphinus?
- small diamond east of Altair.
- What is the brightest star in Delphinus?
- Rotanev, magnitude 3.6.
- Where is Delphinus in the sky right now?
- Open the sky view for your location and time and it shows the position in the sky right now.
The new star that rose in Delphinus in 2013
On 14 August 2013 the Japanese amateur astronomer Koichi Itagaki discovered a new star in Delphinus. Named Nova Delphini 2013, it brightened within two days to magnitude 4.3, visible to the naked eye, one of the few novae of the twenty-first century seen without optical aid. Lying near the small diamond beside the Summer Triangle, it was easy to find and many people saw it for themselves.
The nova also left a scientific mark. Lithium was detected for the first time in the spectrum after the outburst, confirming a long-standing prediction that some of the universe's lithium is made in nova explosions. A piece of the explanation for why stars hold more lithium than the Big Bang produced came from this small constellation. The star has since faded and is visible only in telescopes.
The constellation in depth
Delphinus is one of the 48 ancient constellations catalogued by Ptolemy. In Greek myth it is the dolphin that persuaded the sea nymph Amphitrite to marry Poseidon, or the one that carried the poet Arion to safety after he leapt from a pirate ship. For such a small figure it carries a surprising amount of story.
Its two brightest stars, Sualocin and Rotanev, hide a joke: they are the Latinised name of Niccolò Cacciatore (Nicolaus Venator), an assistant at Palermo Observatory, spelled backwards — the only case of someone quietly naming stars after himself. Gamma Delphini is a lovely double for small telescopes, and the globular cluster NGC 6934 lies nearby.
From July to October find Altair in the south-east, then look about 15 degrees to its left for the little diamond. All four stars are brighter than 4th magnitude, so the shape survives city skies. In the Sky view, set a summer evening and zoom in beside Altair.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.