A Navigational Aid to the Cosmos

Among the 88 official constellations recognized by the International Astronomical Union (IAU), Sextans, named after a navigational instrument, has its own unique place.

Historical Background

Unlike many constellations rooted in ancient mythology, Sextans is a relatively recent addition to the celestial map. It was created in the late 17th century by Polish astronomer Johannes Hevelius. Named after the sextant, a navigational tool used to measure a star's angular distance above the horizon, Sextans serves as a nod to the astronomers' quest for celestial knowledge.

Distinctive Characteristics

Sextans is not the most luminous of constellations - in fact, none of its stars are particularly bright. Its alpha star, Alpha Sextantis, has an apparent magnitude of 4.49, barely visible to the naked eye in optimal viewing conditions. The constellation's relatively dim stars and lack of distinctive patterns make it a challenge to find in the night sky.

Celestial Objects of Interest

Despite its subtlety, Sextans houses a treasure trove of galaxies due to its location away from the Milky Way's plane. Most notably, it is home to the Sextans A and Sextans B dwarf irregular galaxies, both members of our Local Group of galaxies. At a distance of approximately 4.3 and 4.44 million light-years respectively, these galaxies offer a glimpse into cosmic structures beyond our Milky Way.

Another notable object in Sextans is the Black Eye Galaxy (Messier 64). It?s a spiral galaxy distinguished by the dark dust lane and the bright, star-studded nucleus that give it its common name. This galaxy lies at an impressive distance of 17 million light-years from Earth.

Observation

Sextans is best viewed in the spring months for observers in the Northern Hemisphere. It sits between the constellations of Leo to the north and Hydra to the south, which can be used as reference points for locating Sextans.

Given its relatively dim stars, a clear, dark sky, away from city lights and atmospheric pollution, provides the best chance of sighting Sextans. While the constellation's stars can be challenging to see with the naked eye, a small telescope or binoculars will be beneficial for observing its galaxies in more detail.

Sextans may not be the most instantly recognizable constellation in the night sky, but its richness in galaxies provides intriguing observational targets for astronomers. This modest constellation serves as a poignant reminder that sometimes, the quiet and unassuming corners of the cosmos harbor the most fascinating celestial wonders. Whether you are an amateur stargazer or a professional astronomer, the exploration of Sextans offers a celestial adventure that extends far beyond our Milky Way galaxy.

* Constellation shown for northen hemisphere skies. For the southern hemisphere, constellations appear rotated 180 degrees (upside-down and left-right reversed) from what is shown. Remember that seasons are reversed too - summer in northern latitudes is winter in southern latitudes.

** Circumpolar constellations are visible year-round in the hemisphere listed (and not at all in the opposite hemisphere).