Star Constellation Facts: Scutum

Scutum Constellation
Image Credit: IAU and Sky & Telescope magazine (Roger Sinnott & Rick Fienberg)

Scutum (“the shield”) is an extremely small, faint southern sky constellation that was devised by Polish astronomer Johannes Hevelius in 1684 to commemorate King John III Sobieski’s victory at the Battle of Vienna against the Ottoman Turkish Empire a year earlier. Its brightest star, Ionnina, is an orange giant found 174 light years from Earth that shines with a visual magnitude of just +3.85.


Scutum is the 5th smallest constellation, taking up an area of 109 square degrees of the southern celestial sphere. It can be seen by observers situated between +80° and -90°of latitude, and can be viewed from June to August. Scutum is found to the southwest of the bright star Altair in Aquila, which marks the southernmost point in the famous Summer Triangle asterism, and can be located by following a south westwards imaginary line from Altair onto Deneb Okab in Aquila and then Scutum. Other constellations bordering Scutum includes Sagittarius to its north, and Serpens Cauda to its east.

Hercules Constellation Family

Scutum is part of the Hercules family of constellations, along with Aquila, Ara, Centaurus, Corona Australis, Corvus, Crater, Crux, Cygnus, Hercules, Hydra, Lupus, Lyra, Ophiuchus, Sagitta, Sextans, Serpens, Triangulum Australe and Vulpecula.


The Polish King John III Sobieski, along with the Habsburg Monarchy, and the Holy Roman Empire, successfully defeated the Ottoman Turk’s who had laid siege to the imperial city of Vienna in 1683. The victory marked an end to the menace posed by the muslim Ottomans to the Christian world, and in 1684 Polish astronomer Johannes Hevelius honored his king by naming his new constellation Scutum Sobiescianum (“Shield of Sobieski”), which was later shortened to just Scutum.

Meteor Showers

The June Scutids is a meteor shower that takes place between June 2nd and July 29th, with a peak on June 27th when 2 to 4 meteors per hour can be seen.

Principal Stars

Scutum Stars
Image Credit: Torsten Bronger

– Ionnina (Alpha Scuti), the constellation’s brightest star, is orange giant (K2III) situated 174 light from our solar system that shines with an apparent magnitude of 3.85. Being a variable star, though, its brightness does vary by 10 percent, or from between 3.81 and 3.87. This 2 billion years old star is around 15 times bigger than the Sun, with 1.7 times its mass, and 132 times its luminosity.

– Beta Scuti, the second brightest star in Scutum, is a spectroscopic binary system located 690 light years away of magnitude 4.22. Its primary component, Beta Sct A, is a 55 million year old yellow giant (G5II) with about 6 times the Sun’s radius and mass, and 1,270 times its luminosity. Its companion star, Bet Scuti B, is separated by around 17 milli-arcseconds, with the pair having a period of 2.28 years.

– R Scuti, the constellation’s third brightest star, is a yellow supergiant found 1,400 light years away that is also a RV Tauri variable star whose magnitude varies between 4.5 and 8.6 over a 142 day period. It is around 60 times bigger than the Sun, with 6 times its mass, and between 1,500-2,000 its luminosity.

Other stars of interest in Scutum includes the multiple star system Epsilon Scuti; the white subgiant Gamma Scuti; the yellow giant Zeta Scuti; the yellow-white giant Delta Scuti; the orange giant Eta Scuti; and the pulsar PSR B1829-10, which is around 30,000 light years distant and has an apparent magnitude of 5.28.

Notable Deep-Sky Objects

Scutum may be one of the smallest constellation’s in the night sky, but occupying a bright section of the Milky Way means that it is rich in deep-sky objects, including two Messier objects.

Wild Duck Cluster– Wild Duck Cluster (M11, NGC 6705) is an open cluster that is 6,200 light years distant and contains around 2,900 stars, making it one of the densest examples of its kind. This 220 million years old cluster has a visual magnitude of 6.3, and owes its unusual name to a description made by English astronomer William Henry Smyth, who likened it to “a flight of wild ducks”.

– Messier 26 is an open cluster that contains about 90 stars spread out across 22 light-years of space. This 89 million year old cluster is around 5,000 light-years away, and has an apparent magnitude of +8.

IC 1295– IC 1295 is a planetary nebula situated 3,300 light-years away of magnitude 12.7. Striking images taken by ESO’s Very Large Telescope shows a faint white dwarf surrounded by a planetary nebula of green ionized oxygen. Stars with masses up to 8 times that of our Sun form planetary nebulae during the final phase of their lives, as their gaseous atmospheres are expelled into space.

Other objects on interest in the constellation includes the open clusters RSGC1, Alicante 8 (RSGC4), RSGC3, and Stephenson 2 (RSGC2); and the globular clusters NGC 6712 and Mercer 3.

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