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Quadrans Muralis

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Quadrans Muralis was once an official constellation in the night sky. The name means a wall-mounted quadrant. A quadrant is a scientific tool used to measure the position of stars. This constellation is now considered obsolete. This means it is no longer an officially recognized group of stars. It once served as a way to organize specific stars in a certain area.

Quadrans Muralis Constellation Position
Quadrans Muralis Constellation Position

The creation of this constellation began with the astronomer Jérôme Lalande. In 1795, he established the constellation to represent his scientific tools. He used a wall-mounted quadrant to chart the celestial sphere. This process allowed him to map the heavens more accurately. His nephew, Michel Lefrançois de Lalande, assisted him with this work. In a French atlas, they referred to the shape as Le Mural.

Sidney Hall - Urania's Mirror - Bootes, Canes Venatici, Coma Berenices, and Quadrans Muralis
Sidney Hall - Urania's Mirror - Bootes, Canes Venatici, Coma Berenices, and Quadrans Muralis

As time passed, the boundaries of the constellation changed. Johann Elert Bode was an astronomer who published a star atlas called Uranographia in 1801. Bode converted the French name into the Latin name Quadrans Muralis. He also decided to shrink the size of the constellation. He did this to prevent it from clashing with neighboring star groups. This adjustment changed which stars were considered part of the shape.

Sidney Hall - Urania's Mirror - Bootes, Canes Venatici, Coma Berenices, and Quadrans Muralis
Sidney Hall - Urania's Mirror - Bootes, Canes Venatici, Coma Berenices, and Quadrans Muralis

The constellation occupied a specific location in the sky. It sat between the constellations Boötes and Draco. It was also located near the tail of Ursa Major. The stars within its borders ranged from β Bootis, also known as Nekkar, to η Ursae Majoris, known as Alkaid. Different versions of the constellation featured different bright stars. In Lalande’s original version, 44 Boötis was the brightest star. In Bode’s 1801 version, the brightest star was CL Draconis.

Quadrans Muralis Constellation Position
Quadrans Muralis Constellation Position

Several specific stars were linked to this obsolete group. The star 39 Boötis is a double star that Lalande moved into the constellation. Another star, BP Boötis, is a variable star that was also a member. Even though the constellation is no longer official, its legacy remains in star names. In 2025, the IAU Working Group on Star Names named a star Quadrans. This star is the primary component of the system 44 Boötis A.

Quadrans Muralis Constellation Position
Quadrans Muralis Constellation Position

The status of the constellation changed forever in the early 20th century. In 1922, the International Astronomical Union, or IAU, formalized the list of recognized constellations. This organization created a standard set of shapes for astronomers to use. During this process, Quadrans Muralis was omitted from the official list. Because it was left off, it is no longer used as a standard celestial region.

Quadrans Muralis Constellation Position
Quadrans Muralis Constellation Position

Despite being obsolete, the name Quadrans Muralis still connects to modern astronomy. The Quadrantid meteor shower is still named after this former constellation. This event brings a display of shooting stars to the sky every year. The history of the constellation shows how our maps of the universe change. It demonstrates how astronomers like Lalande and Bode worked to organize the stars. The transition from Le Mural to Quadrans Muralis shows the evolution of scientific naming.

Sidney Hall - Urania's Mirror - Bootes, Canes Venatici, Coma Berenices, and Quadrans Muralis
Sidney Hall - Urania's Mirror - Bootes, Canes Venatici, Coma Berenices, and Quadrans Muralis
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File:Quadrans Muralis Constellation Position.jpg
Quadrans Muralis Constellation Position.jpg
File:Sidney Hall - Urania's Mirror - Bootes, Canes Venatici, Coma Berenices, and Quadrans Muralis.jpg
Sidney Hall - Urania's Mirror - Bootes,...
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