the lizard · pronounced luh-SUR-tuh. Lacerta is a small northern constellation threaded through the Milky Way between Cygnus and Andromeda. Johannes Hevelius introduced the Lizard in the seventeenth century to fill a gap between older figures. Its zigzag resembles a miniature Cassiopeia but contains no star brighter than magnitude 3.8. Open clusters NGC 7243 and NGC 7209 reward binocular scanning, while BL Lacertae gave its name to an entire class of violently variable active galactic nuclei.
About Lacerta
Lacerta is one of the 88 constellations recognized by the International Astronomical Union. Its standard three-letter abbreviation is Lac, and astronomers use the genitive form Lacertae when naming stars associated with it. The constellation's reference position lies around right ascension -1.2 hours and declination +47 degrees.
Its location places it in the northern sky. For a typical mid-latitude observer, this part of the celestial sphere is especially well placed during summer evenings. Exact visibility depends on latitude, local horizon, date and time.
History and mythology of Lacerta
Hevelius’s lizard
Johannes Hevelius published Lacerta in Firmamentum Sobiescianum in 1687. He also mentioned an alternative association with a sceptre and hand of justice, but the lizard name survived.
A gap in the northern Milky Way
Hevelius constructed the figure in a relatively faint area among Cygnus, Cepheus, Cassiopeia, Andromeda and Pegasus. Its creation illustrates how early-modern atlas makers added figures between Ptolemy’s ancient constellations.
From variable star to blazar class
BL Lacertae was first catalogued as an irregular variable star. Astronomers later recognised it as the active nucleus of a distant galaxy aimed nearly along its relativistic jet; similar objects are now called BL Lac objects.
The modern astronomical region
The IAU adopted the three-letter abbreviation and standard constellation name in 1922. Eugène Delporte then published the coordinate boundaries in 1930, turning the inherited figure into an exact address for cataloguing every object inside it.
How to find Lacerta
- Find the W of Cassiopeia and the Northern Cross of Cygnus. Lacerta occupies the Milky Way gap between them, just north of Pegasus.
- Use Alpha and Beta Lacertae to begin the constellation’s narrow zigzag. Binoculars are helpful because most pattern stars are fourth or fifth magnitude.
- September and October evenings place Lacerta high for northern observers. Its Milky Way setting benefits greatly from a moonless, low-light-pollution site.
- Sweep around Alpha Lacertae for NGC 7209 and farther south for NGC 7243; both look best at low power.
Bright stars in Lacerta
Alpha Lacertae
Notable star- Magnitude
- 3.77
- Distance
- about 103 light-years
A white main-sequence star and Lacerta’s brightest visual anchor.
1 Lacertae
Notable star- Magnitude
- 4.13
- Distance
- about 620 light-years
An orange supergiant near the constellation’s northern end, intrinsically far brighter than nearby-looking Alpha Lacertae.
Beta Lacertae
Notable star- Magnitude
- 4.42
- Distance
- about 170 light-years
A yellow giant forming the second major point in Lacerta’s zigzag.
EV Lacertae
Notable star- Magnitude
- about 10.1, flare variable
- Distance
- about 16.5 light-years
A nearby red dwarf famous for powerful flares; it is invisible to the unaided eye in its normal state.
Deep-sky objects in Lacerta
NGC 7243
A loose, young cluster visible in binoculars as a grainy patch and resolved into several dozen stars with a small telescope.
NGC 7209
A broad, moderately rich open cluster whose mixed-brightness stars stand out best at low magnification.
BL Lacertae
The prototype BL Lac object, changing brightness as a relativistic jet from a supermassive black hole points close to our line of sight.
Interesting facts about Lacerta
- Lacerta's name means the lizard. Johannes Hevelius published Lacerta in Firmamentum Sobiescianum in 1687.
- Alpha Lacertae is listed at magnitude 3.77. A white main-sequence star and Lacerta’s brightest visual anchor.
- NGC 7243 is an open cluster. A loose, young cluster visible in binoculars as a grainy patch and resolved into several dozen stars with a small telescope.
- Hevelius constructed the figure in a relatively faint area among Cygnus, Cepheus, Cassiopeia, Andromeda and Pegasus.