Horologium Constellation Facts, Myth, Location and Stars  

The following article summarizes the facts and mythology surrounding the Horologium constellation.

Horologium Constellation Facts, Myth, Location and Stars  

The Horologium constellation is in the sky’s southern hemisphere, and it is the 58th largest constellation out of the 88 modern constellations.

Stretching over 249 square degrees, Horologium is bordered by several other constellations, namely Hydrus, Eridanus, Reticulum, Dorado, and Caelum.

The name Horologium, meaning “the clock,” was given in 1752 by French astronomer Nicolas Louis de Lacaille in honor of the man who had invented the pendulum clock a century before – Christiaan Huygens.

The Horologium differs from other constellations because it does not have any myths or legends surrounding it.

Due to its relatively small size, the Horologium constellation occupies only 0.603% of our sky, ranking 58th out of the 88 modern constellations.

Forty-one stars in the Horologium constellation are equal in brightness or brighter than a magnitude of 6.5.

Horologium Constellation Myths

Unlike other constellations, there are no myths or legends surrounding the Horologium.

The constellation’s name, meaning “the clock” in Latin, was given by French astronomer Nicolas-Louis de Lacaille.

In 1752, Lacaille traveled to the Cape of Good Hope to observe the southern sky.

In his two-year stay there, he coined the Horologium in honor of Christiaan Huygens, the Dutch mathematician who invented the pendulum clock.

Horologium Constellation Location

The Horologium constellation is located in the first quadrant of the southern hemisphere of the sky (SQ) and can be seen by observers south of 23° N.

The constellation is visible at latitudes between +30° and -90°

When to see it:

Since it is a seasonal constellation, Horologium cannot be observed all throughout the year.

The best time to see it is in December, at 9:00 pm/ 21:00.

How to find it:

The best way to find the Horologium constellation is by identifying Archenar, the brightest star in the Eridanus constellation.

The constellation is represented as a river, known as the Eridanus River.

By identifying and tracing the first half of the Eridanus River from the Archenar star, observers can look southwest of the River to find Horologium, which can be identified as a darker area of sky.


Some of the more important stars in the Horologium constellation are Alpha Horologii, R Horologii, Beta Horologii, Delta Horologii, Iota Horologii, Lambda Horologii, Mu Horologii, Nu Horologii, HD 27631, and Gliese 1061.

Alpha Horologii

  • Out of all the stars in the Horologium constellation, Alpha Horologii is the brightest.
  • It is located approximately 115 light-years away from our Solar System.
  • Alpha Horologii is an orange giant star with a magnitude estimated at 3.85, making up the constellation outline.
  • This star is spectral type K1III.

R Horologii

  • R Horologii is the second brightest star in the Horologium constellation and is categorized as a red giant star.
  • It has the most extensive variations in brightness in the Horologium, ranging from 4.7 to 14.3.
  • R Horologii is located approximately 100 light-years from Earth and has a magnitude of 4.7.
  • It is spectral type M7IIIe and has been classified as a Mira variable.

Beta Horologii

  • Beta Horologii is the third brightest star in the Horologium and is categorized as a blue giant star.
  • It has a magnitude of 4.979.
  • It is located approximately 312 light-years from Earth.
  • Due to its strong absorption lines of metals, Beta Horologii is considered to be an unusual star.
  • Beta Horologii is spectral type A4IIIm
  • Compared to the Sun, Beta Horologii is hotter (with temperatures of 8,303 K) and 63 times brighter.

Gliese 1061

  • Gliese 1061 is significantly closer to the Earth than other stars in the Horologium constellation, at approximately 11.99 light-years.
  • It is ranked the 20th closest known star to the Sun and has a magnitude of 13.3.
  • In comparison to the Sun, Gliese 1061 has 11.3 of its mass.
  • Gliese 1061 is spectral type M5.5V
  • It is categorized as a red dwarf star and has three known exoplanets orbiting it.

Iota Horologii

  • Iota Horologii is an F-type dwarf star located 56 light-years from Earth.
  • It is spectral type G0Vp, with a visual magnitude of 5.40.
  • Iota Horologii hosts an exoplanet approximately the size of Jupiter, which has been named Iota Horologii b.

Lambda Horologii

  • Lambda Horologii is a yellow-white hued evolved star
  • It has a magnitude of 5.35 and is located 155.2 light-years from Earth.
  • Lambda Horologii is 13.3 brighter than the Sun, with temperatures of 6,848 K
  • Due to its 140 km/sec rotational velocity, it is also considered a fast-spinning star.
  • The star is 1.4 billion years old.

Mu Horologii

  • Mu Horologii is currently an F-type star.
  • Mu Horologii is gradually becoming a giant or giant star.
  • Located 141.6 light-years away from the Sun, it is estimated to be two billion years old.

Nu Horologii

  • Nu Horologii is a white-hued main-sequence star with a visible magnitude of 5.25.
  • Because of its magnitude, Nu Horologii can be seen with the naked eye.
  • It is estimated to be 540 million years old and 169 light-years from Earth.
  • The star has a brightness of 16.7 times that of the Sun.

HD 27631

  • HD 27631 has a magnitude of 8.24 and is a G-type star.
  • It is 164.3 light-years from Earth and about 4 billion years old.
  • The star has an exoplanet, which was given the name HD 27631 b.
  • HD 27631 has 94% of the Sun’s mass and 88% of its brightness.

Delta Horologii

  • Delta Horologii is the second brightest star in the Horologium constellation.
  • It is located 179 light-years away from the Sun and has a magnitude of 4.93.
  • Delta Horologii is composed of:
  • Delta Horologii A: a white star estimated to be 768 million years old; its mass is 1.4 times that of the Sun, and it received a stellar classification of A9.
  • Delta Horologii B: has a rotational velocity of 51.7 km/s and a magnitude of 7.29.


The Horologium constellation ranks 58th out of the 88 modern constellations and stands out in the fact that no myths or legends are associated with it.

Located in the southern hemisphere sky, and best observed throughout the month of December, the Horologium can be identified by tracing the Eridanus River, starting from the Archenar star, the brightest star in the Eridanus constellation.

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