Scutum, the Shield, is a small, faint constellation in a particularly rich part of the summer Milky Way. Although it has few bright stars, it contains one of the finest open star clusters in the sky: the Wild Duck Cluster (Messier 11).
Covering approximately 109 square degrees, Scutum is the fifth-smallest of the 88 recognized constellations. It is best explored with binoculars or a telescope on clear summer evenings.
Where and When to Find Scutum
Scutum is most conveniently observed from June through September. It lies south of Aquila, north of Sagittarius, and beside the tail of Serpens.
Begin with Altair, the bright star at the southern corner of the Summer Triangle. From Altair, look south toward the Milky Way’s dense star fields. Scutum lies in this direction, above the Teapot-shaped pattern of Sagittarius. Its brightest stars are only around fourth magnitude, so the constellation itself can be difficult to trace under suburban skies. The surrounding Milky Way, however, is a spectacular binocular target.
History of Scutum
Scutum is one of the few constellations named for a historical event rather than a mythological figure or animal. The Polish astronomer Johannes Hevelius introduced it in 1684 as Scutum Sobiescianum, meaning “Sobieski’s Shield.” It honored King John III Sobieski of Poland, whose forces played a decisive role in lifting the Ottoman siege of Vienna in 1683. The name was later shortened to Scutum, Latin for “shield.”
Notable Stars
- Ionnina (Alpha Scuti) is the constellation’s brightest star, an orange giant approximately 175 light-years away. It shines at about magnitude +3.9 and shows slight variations in brightness.
- Beta Scuti is a yellow evolved star in a binary system, with a combined apparent magnitude of approximately +4.2.
- Delta Scuti is a yellow-white variable star that gave its name to the Delta Scuti class of pulsating variables. These stars brighten and fade as their outer layers expand and contract.
- R Scuti is a striking RV Tauri variable star whose brightness can change dramatically over several months. At its brightest, it is visible to the naked eye under dark skies; at minimum, binoculars may be needed.
Notable Deep-Sky Objects
Wild Duck Cluster (M11)
The Wild Duck Cluster (Messier 11, NGC 6705) is Scutum’s best-known attraction. Located roughly 6,000 light-years away, this exceptionally rich open cluster contains thousands of stars packed into a relatively small region of space. At around magnitude +6.3, M11 is visible through binoculars as a small hazy patch. A modest telescope begins to resolve its stars, while larger instruments reveal a densely populated field. The cluster’s nickname comes from the 19th-century astronomer William Henry Smyth, who compared its arrangement of brighter stars to a flight of wild ducks.
How to find it: Look near the northern edge of Scutum, just south of Aquila. The cluster lies in the bright Milky Way region known as the Scutum Star Cloud. A star chart and low-power binoculars make the search easier.
Other Objects
- Messier 26 is another open cluster in Scutum, located approximately 5,000 light-years away. It is smaller and less conspicuous than M11, shining at around magnitude +8. It appears as a compact gathering of stars in a small telescope.
- IC 1295 is a faint planetary nebula near the globular cluster NGC 6712. Its glowing gas was expelled by an aging star, leaving behind a hot stellar remnant. It is a challenging target for larger amateur telescopes, particularly under dark skies.
- Scutum also contains the globular cluster NGC 6712 and several heavily obscured young star clusters. The region’s dense Milky Way background makes it particularly rewarding for wide-field binocular observing.
Observing Scutum
Scutum’s appeal lies less in its faint constellation outline than in the remarkable Milky Way scenery around it. Start with binoculars to explore the Scutum Star Cloud, then use a telescope to examine M11’s crowded center. For observers following the summer Milky Way southward from Aquila toward Sagittarius, Scutum is a small constellation well worth stopping to explore.