Puppis (the Stern) is a large southern constellation that once formed part of Argo Navis, the ancient constellation representing the ship used by Jason and the Argonauts in Greek mythology. Today, the ship is divided into three constellations: Puppis (the Stern), Carina (the Keel), and Vela (the Sails).
Puppis lies along a rich section of the Milky Way and contains some excellent targets for amateur astronomers, including three Messier star clusters and the colorful Skull and Crossbones Nebula. Its brightest star, Naos, is an exceptionally hot and luminous blue supergiant.
Where Is Puppis and When Can You See It?
Puppis is the 20th-largest constellation, covering approximately 673 square degrees of the sky. It lies southeast of Canis Major and borders Carina, Columba, Hydra, Monoceros, Pictor, Pyxis, and Vela.
The best time to observe Puppis is January through March, particularly February, when it is well placed in the evening sky. Puppis is most easily observed from the Southern Hemisphere, although much of it is visible from lower northern latitudes. Its northernmost regions can be seen low on the southern horizon from southern Britain under favorable conditions.
To find Puppis, begin with Sirius, the brightest star in the night sky, in neighboring Canis Major. Look southeast toward the Milky Way, where Puppis occupies a broad region filled with star clusters. Its brightest star, Naos, lies in the southern part of the constellation.
History and Mythology of Puppis
Puppis was originally part of Argo Navis, one of the 48 constellations recorded by the Greek astronomer Ptolemy in the 2nd century AD. In Greek mythology, the Argo was the ship that carried Jason and the Argonauts on their voyage to recover the Golden Fleece.
Argo Navis was an enormous constellation, covering a much larger area than most other ancient star patterns. During the 1750s, French astronomer Nicolas-Louis de Lacaille reorganized the constellation into smaller sections while mapping the southern sky from South Africa. The resulting constellations were Puppis, Carina, and Vela.
Unlike most modern constellations, Puppis has no Alpha-designated star because the original Greek-letter designations from Argo Navis were largely retained when the ship was divided.
Notable Stars in Puppis
- Naos (Zeta Puppis) – The constellation’s brightest star, a hot blue O-type supergiant shining at magnitude 2.2. It lies roughly 1,000 light-years away and is hundreds of thousands of times more luminous than the Sun. Naos is also notable for its powerful stellar wind, which carries enormous quantities of material into space.
- Pi Puppis – An orange supergiant approximately 800 light-years away, shining at magnitude 2.7. It is associated with a loose grouping of young stars known as the Pi Puppis Cluster.
- Rho Puppis (Tureis) – A yellow-white evolved star approximately 63 light-years away, with an apparent magnitude around 2.8. It is a low-amplitude pulsating variable star.
- Xi Puppis (Asmidiske) – A yellow supergiant approximately 1,200 light-years away, shining at magnitude 3.3.
- Nu Puppis – A blue-white giant approximately 370 light-years away, with an apparent magnitude around 3.2.
- HD 69830 – A Sun-like star approximately 41 light-years away, notable for its system of three known Neptune-mass planets.
Notable Deep-Sky Objects in Puppis
Puppis lies along the Milky Way, making it especially rich in open clusters and star-forming regions. Three of its clusters appear in Charles Messier’s famous catalog.
Messier 46 — A Rich Open Cluster
Messier 46 (M46 or NGC 2437) is an open cluster approximately 5,000 light-years away, containing several hundred stars. With an apparent magnitude around 6.1, it is a rewarding binocular and small-telescope target under dark skies.
One of its most interesting features is the planetary nebula NGC 2438, which appears superimposed on the cluster. Although the nebula seems to lie among M46’s stars, it is generally considered a foreground object rather than a physical member of the cluster.
M46 is approximately 250–300 million years old and appears as a dense grouping of relatively faint stars through a telescope.
Messier 47 — A Bright, Loose Star Cluster
Messier 47 (M47 or NGC 2422) is a bright open cluster approximately 1,600 light-years away. It contains several dozen prominent stars and shines at an apparent magnitude around 4.4, making it visible to the naked eye under good conditions.
M47 is much younger and more loosely arranged than M46, with several bright blue-white stars standing out in binoculars. The two clusters lie only about 1.5 degrees apart in the sky, making them an excellent pair to compare through binoculars or a wide-field telescope.
Messier 93 — A Compact Open Cluster
Messier 93 (M93 or NGC 2447) is an open cluster approximately 3,600 light-years away. It contains dozens of stars concentrated into a relatively compact region, with an apparent magnitude around 6.0. Through binoculars, M93 appears as a small, hazy patch. A telescope reveals its brighter individual stars and the cluster’s irregular arrangement.
Its age is estimated at roughly 100 million years, making it another relatively young stellar grouping.
Skull and Crossbones Nebula — NGC 2467
The Skull and Crossbones Nebula (NGC 2467) is a colorful star-forming region containing glowing hydrogen gas, dark dust clouds, and young stellar clusters. It lies several thousand light-years away in the direction of Puppis and is part of a larger complex of star-forming material.
Radiation from hot, massive stars causes the surrounding hydrogen to glow, while dense clouds of gas and dust provide the raw material for future generations of stars.
Its dramatic appearance in astronomical photographs has earned it the nickname Skull and Crossbones Nebula.
Other Star Clusters in Puppis
Puppis contains several additional open clusters, including NGC 2477, one of the richest open clusters in the southern sky, and NGC 2451, a bright grouping visible through binoculars.
Other notable clusters include NGC 2546, NGC 2439, and NGC 2509.
Together, these objects make Puppis an especially rewarding constellation for observers interested in exploring the star clusters of the Milky Way.