Sagittarius Constellation: Brightest Star, Shape, and Star Charts

The Brightest Star of Sagittarius: Kaus Australis

Sagittarius, the Archer, is a zodiac constellation in the southern sky. Its brightest star is Epsilon Sagittarii, traditionally known as Kaus Australis, which shines at an apparent magnitude of +1.85. This makes it the 36th brightest star in the entire night sky. Kaus Australis is a blue-white giant located approximately 143 light-years from Earth. Its name derives from Arabic, meaning "the southern bow," as it marks the lower part of the Archer's bow.

While Kaus Australis is the most luminous point in Sagittarius, the constellation is also home to several other notable stars, including Nunki (Sigma Sagittarii) at magnitude +2.05 and Ascella (Zeta Sagittarii) at +2.60. These stars form the Archer's bow and are part of the larger Teapot asterism.

How to Find the Shape of Sagittarius in the Night Sky

Locating Sagittarius can be a rewarding challenge for stargazers. The constellation is best seen during the Northern Hemisphere's summer months (June to August) and is visible from most inhabited regions, though it appears higher in the sky from southern latitudes.

To find Sagittarius, look for the distinctive Teapot asterism. The Teapot is formed by eight stars: Kaus Australis, Kaus Media, Kaus Borealis, Ascella, Nunki, Phi Sagittarii, Tau Sagittarii, and Zeta Sagittarii. The handle of the Teapot points toward the Scorpius constellation, and the spout points toward the center of the Milky Way.

A useful method is to use the bright star Antares in Scorpius as a guide. Draw a line from Antares toward the east, and you will encounter the Teapot. Alternatively, use the Summer Triangle (Vega, Deneb, and Altair) and follow the line from Altair southward to reach Sagittarius.

The Archer's Bow

The full shape of Sagittarius is more complex than the Teapot. The constellation depicts a centaur archer, with the bow formed by the stars Kaus Borealis, Kaus Media, and Kaus Australis. The arrow points toward the Scorpion's heart, Antares. The centaur's body and legs extend southward, though these fainter stars are less obvious in light-polluted skies.

Sagittarius in Star Charts and Its Celestial Context

On a star chart, Sagittarius is located between Scorpius to the west and Capricornus to the east. It lies along the ecliptic, the path the Sun appears to take across the sky, which is why it is one of the zodiac constellations. The Sun passes through Sagittarius from mid-December to mid-January.