What is the constellation Cancer?
The crab (Crab, ♋) is one of the 88 modern constellations (Cancer according to the Latin terminology adopted by the IAU) and one of the twelve constellations of the zodiac. Cancer It is small and tenuous, and to many it does not look like a crab.
One of its stars, 55, stands out because it has 5 planets orbiting around it, one of the most numerous systems discovered outside the Solar System.
It is located between the constellations of Gemini to the East, Lynx in the North and the constellations of Canis Minor and Hydra in the South.
The constellation also gives its name to the Tropic of Cancer.
Cancer: Main stars
α Cancri
α Cancri (Acupens), a white star of magnitude 4.26, is only the fourth brightest in the constellation.
β Cancri
β Cancri (Altarf), the brightest of the constellation with magnitude 3.53 is an orange giant 290 light years away.
ζ Cancri
ζ Cancri (tegmen or Tegmine), star system composed of two binary stars separated by 5.06 arc seconds. In total it contains at least four stars.
ι Cancri
ι Cancri, visual binary whose components, separated by 30.6 arc seconds, can be resolved with a small telescope.
κ Cancri
κ Cancri, double system formed by a bluish-white variable star Alpha2 Canum Venaticorum and a white star.
55 Cancri
55 Cancri (ρ1 Cancri), binary star the main component is a yellow dwarf with a planetary system with five planets.
X Cancri
X Cancri, carbon star of magnitude 6.28.
DX Cancri
DX Cancri, blazing star just 11.82 light years from Earth.
Celestial bodies Cancer
Cancer It has no bright stars. α Cancri It only has magnitude 4.2. Cancer is known among astronomy fans as the constellation in which Praesepe (M44), also known as ‘The manger‘, an open cluster that also contains the star ε Cancri and that can be observed with simple binoculars. The Manger covers more than a square degree, being observable with the naked eye as a diffuse light; Located inside the Manger (although very far behind it), there is a group of galaxies belonging to the Coma – Virgo cluster that are only visible with medium-power telescopes. Other deep sky objects found in Cancer are M67, an open cluster known from very ancient times, and NGC 2775a, a magnitude 11.3 spiral galaxy. On a clear night the constellation contains about 50 stars visible to the naked eye.
History and mythology of Cancer
The crab constellation and the Hydra constellation are related to one of the twelve labors of Heracles (Roman Hercules). The goddess Hera, a staunch enemy of Heracles, sent a giant crab to end his life while he was fighting with the fearsome snake Hydra. However, Heracles was victorious. As a reward for her efforts the goddess formed the constellations of the Crab and the Hydra in the sky.