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Glossary term: Cáncer

Description: Cáncer es una de las constelaciones del Zodíaco, es decir, las estrellas que forman esta constelación se encuentran en la parte del cielo que se cruza con la eclíptica (el plano definido por la trayectoria de la Tierra alrededor del Sol). Por lo tanto, desde la Tierra, podemos encontrar regularmente al Sol, y también planetas, en la constelación de Cáncer. En el caso del Sol, esto ocurre desde finales de julio y principios de agosto (en esa época, por supuesto, no podemos ver las estrellas de la constelación). Hace dos mil años el Sol estaba en Cáncer durante el solsticio de verano del hemisferio norte, de ahí el nombre del Trópico de Cáncer. Debido a la precesión de los equinoccios, el Sol ya no se encuentra en Cáncer en el solsticio de verano del hemisferio norte. Cáncer es una de las 88 constelaciones modernas definidas por la Unión Astronómica Internacional, pero se remonta mucho más atrás: ya era una de las 48 constelaciones nombradas por el astrónomo del siglo II Claudio Ptolomeo.

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Term and definition status: The original definition of this term in English have been approved by a research astronomer and a teacher
The translation of this term and its definition is still awaiting approval

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".

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The curve of the Milky Way over a road. Bottom left, two bright stars form a line pointing to a kite-shaped stellar assembly

Most Brightest Stars of the Sky

Caption: Honourable mention in the 2022 IAU OAE Astrophotography Contest, category Still images of celestial patterns.   Taken in March 2016 in Bromo-Tengger-Semeru National Park, Java Island, Indonesia, this image shows the arch of the Milky Way and many prominent constellations, including many of the brightest stars in the night sky. In the lower-left corner, we see Rigil Kentaurus and Hadar, the first one lower and the other higher up, both located in the large constellation Centaurus. As pointers they point towards Crux, the Southern Cross, whose long axis points towards the southern pole, which is located roughly at the horizon because the Island of Java is almost at the equator. Crux is almost entirely obscured by clouds, with only the four bright stars visible in the photograph. Confusingly, the asterism of the False Cross (consisting of stars in Argo, The Ship) is clearly prominent a bit further up the Milky Way. The pinkish spot between the true and the False Cross is the Carina Nebula, located about 8500 light-years from Earth, in the constellation Carina, and invisible to the unaided eye. In Carina we can also find Canopus, the second-brightest star in the night sky, seen just below the Galaxy and above the road on the ground. Even brighter is Sirius, the brightest star in the night sky. Sirius lies in the constellation Canis Major, The Great Dog, one of the dogs that follow Orion, the Hunter, who is depicted in the right half of this image, just above the clouds at the horizon. Orion’s Belt of three bright stars points to Sirius in the upper left and to Aldebaran in the lower right, just above the horizon. Orion contains some of the brightest stars in the sky, making it the most colourful constellation as it hosts Rigel, the bright bluish star below the Galaxy toward the right, and Betelgeuse, the reddish bright star higher up and to the right of Rigel. Between them we find the three stars that comprise the belt of Orion, a famous asterism. Just next to the belt we find the Great Orion Nebula, a star-forming region whose bright centre is visible to the unaided eye and also in this image. Above Betelgeuse but on the opposite side of the Galaxy, we see the bright star Procyon, whose name means literally “Before the Dog”. It is mythologically often considered a tiny one-star dog asterism accompanying Orion, and transformed into the modern constellation of Canis Minor. In the upper-right corner, the Beehive Star Cluster in the constellation Cancer is easily recognisable. Below it, we find the constellation Gemini with the stars Pollux and Castor, which are not prominent in this image. In contrast, the bright white star Capella in the constellation Auriga, the Charioteer, shines through the clouds at the middle-right edge of the image. Some light pollution is visible along the road.
Credit: Giorgia Hofer/IAU OAE

License: CC-BY-4.0 Creative Commons Reconocimiento 4.0 Internacional (CC BY 4.0) icons